ObjectiveSkin cancer is among the most common cancers worldwide. Skin cancer screening relies primarily on visual inspection by dermatologists, and largely depends on their experience. However, imbalances in regional development have led to an uneven distribution of medical resources worldwide. Telemedicine is an effective approach to alleviate this dilemma, and a major branch of this field is teledermatology. Dermatologists can remotely view clinical images and medical histories of skin cancer patients in various ways and provide remote diagnosis and treatment suggestions. However, teledermatology relies on medical experts and network conditions, and patients who cannot access the Internet in remote areas cannot enjoy the convenience of remote consultation. Some portable devices based on automatic diagnostic algorithms have made up for some shortcomings of traditional teledermatology; however, because they can only judge the type of disease, these devices have limited clinical applicability. To compensate for the shortcomings of the current research, our team design and build a skin tumor artificial intelligence-enhanced teleconsultation system, which has both offline automatic skin tumor screening and online remote consultation and preoperative planning functions.MethodsIn this study, we build a skin tumor intelligent teleconsultation system with two typical application scenarios: 1) skin tumor self-screening without network conditions. Patients or doctors who lack experience at the local site can use the dermatoscope in the system to obtain images of skin lesions and then use the deep learning algorithm in the system to generate automatic diagnosis results. 2) Remote skin tumor consultation under network conditions. Remote consultation for skin tumors involves real-time interactions among inexperienced doctors at a local site and experienced medical experts at a remote site. First, the doctor at the local site uses a dermatoscope or ordinary camera in the system to obtain skin images of patients with skin tumors. Then, the deep learning algorithm in the system generates automatic diagnosis results based on the images. Finally, the remote expert confirms the disease diagnosis result and recommends a corresponding treatment plan based on network-transmitted images and algorithmic cues. For patients requiring surgery, both parties can use the system for preoperative planning. Instructive annotations drawn by remote doctors on the screen are transmitted over the network to the local site and projected onto the body surface of the patient in situ. To achieve the above functions, we first train a RegNetY-800M model based on 7-point dataset and deploy it on Raspberry Pi, also using a neural network computing accelerator to accelerate neural network computation, then use camera, laser projector, and beam splitter to form a co-axial projective imaging design that can project instructive annotations made by remote experts with high accuracy onto patient's body surface, finally design a visual software interface for easy use by doctors. To characterize the system, we first design a benchtop experiment to quantify the achievable accuracy of the system, then design a control experiment to verify whether the system can improve the applicability and efficiency of the traditional teleconsultation system. Finally, a clinical experiment is designed to verify the clinical applicability of the system.Results and DiscussionsThe benchtop experimental results show that the maximum projection error of the system is less than 1.5 mm (Fig.4), and the CIEDE2000 value after color correction is less than 2, which can accurately restore colors in the scene (Fig.5). The control experimental results show that there is no significant difference between the algorithm in the system and dermatologists; dermatologists perform better with AI prompts. Clinical experimental results show that using this system for automatic diagnosis and remote consultation of skin tumors is feasible.ConclusionsThe intelligent teleconsultation system for skin tumors designed and built by our team has both automatic disease screening without a network and remote consultation with the network. The control experimental results show that the diagnostic results of the algorithm deployed in the system are comparable to those of dermatologists and that the algorithm can help dermatologists make more efficient and accurate decisions. The experimental results show that the system has clinical applicability. Compared to traditional remote consultation systems, this system has the following three advantages. 1) It has a wider application range. In remote areas without a network, the system can serve as a supplement to dermatologists, compensating for defects in which traditional teleconsultation systems cannot be used without a network. 2) Better performance. Automatic diagnosis results in the system can assist specialists in a more efficient and accurate screening of skin tumors. 3) Intuitive display. This system can project annotations made by remote experts onto body surfaces of patients with high precision, thereby making remote guidance in preoperative consultations and surgical planning processes more intuitive and precise. This system can help patients in areas with scarce medical resources perform early screening for various diseases, such as skin tumors.

ObjectiveGlioma is an invasive malignant primary brain tumor, characterized by its infiltrative growth pattern, making it challenging to differentiate its boundaries from healthy brain tissues during surgical procedures. Our study aims to address the challenge of accurately distinguishing glioma from healthy brain tissues. Based on a home-made high-resolution polarization-sensitive optical coherence tomography (PS-OCT) system, we conduct ex vivo imaging of normal mouse brain and human glioma model mouse brain. Further, based on the polarization analysis of the tumor and normal brain tissues, we propose a novel tumor differentiation metric called optic axis standard deviation to distinguish normal and glioma tissues. It is proven by the results that high-resolution PS-OCT has great potential in imaging brain tissue and can offer enhanced precision to detect glioma during surgical interventions, which will help to solve the urgent clinical need in neurosurgical practice.MethodsA home-made spectral domain PS-OCT system is constructed by utilizing a superluminescent diode as a broad-spectrum light source. The system is performed with an axial resolution of 3.4 μm in air and a transverse resolution of 4 μm in the focal plane. The low-coherence light beam emitted by the broad-spectrum light source is linearly polarized in the vertical direction after passing through a linear polarizer. Through the integration of a quarter-wave plate and a polarizing beam splitter, circularly polarized light enters the sample arm, while orthogonally polarized signals are detected in the detection arm. After collecting the spectral signals corresponding to the two orthogonal polarization states, the parameters of intensity, phase retardation, and optic axis are calculated and the corresponding OCT images are obtained.Given the similarity of genomes between the mouse and human, the mouse brain is chosen as the imaging object in this study. A human glioma mouse model is established by injecting U87-GFP human glioma cells into the mouse brain. The model is euthanized and fixed 5 weeks after establishment. Subsequently, green fluorescent protein (GFP) fluorescence imaging and PS-OCT imaging are performed on the mouse brain. Three-dimensional field of view of PS-OCT imaging is 6 mm×3 mm×2.3 mm. The three-dimensional image contains 1000 B-scans, and each B-scan image consists of 2000 pixel×2000 pixel (x and z directions). The image in the x-y direction is extracted from the three-dimensional image to obtain the en-face image along the cross section of the sample.Results and DiscussionsIn the OCT images of the normal mouse brain (Figs. 2 and 3), neural fiber bundles in different directions can be clearly observed. In the polarization images, these fiber structures are more pronounced, manifested as radiating short lines. The mouse cerebral cortex exhibits polarization-maintaining properties without birefringence changes. The internal capsule structure between the cortex and internal brain regions is visible with birefringent properties, leading to notable variations in phase retardation. The hippocampal structure lacks birefringent characteristics, resulting in a low value of the phase retardation.Contrasting with fluorescence imaging results to determine the tumor location in the mouse brain (Figs. 4 and 5), it can be seen from the OCT images that there is no significant birefringence change in the tumor tissue, the color of the polarized images becomes more homogenous, and we can find that the infiltration of tumor cells leads to strong fiber damage, and there is no prominent linear structure in the optic axis results.The optic axis histogram (Fig. 6) illustrates distinctive distribution features between normal brain tissue and glioma tissue. The optic axis of normal brain tissue is uniformly distributed between -π/2 rad and π/2 rad, while the optic axis in the glioma region is mainly concentrated near 0 rad. By calculating the standard deviation of the optic axis value within the spatial window, the evaluation parameters of optical axis standard deviation are established. The range and mean value of optic axis standard deviation in normal brain tissue far exceed those in glioma tissue. The quantitative analysis underscores substantial distinctions of polarization information between tumor and normal mouse brain tissues.Within brain tissue, myelinated nerve fibers exhibit pronounced scattering and birefringence properties. The results of this study indicate that normal mouse brain tissue, rich in myelinated nerve fibers, is effectively identified by PS-OCT. The high-resolution intensity map contains detailed information, and the phase retardation highlights the birefringence changes of structures such as internal capsules and nerve fiber bundles. The optic axis values reflect the oriented arrangement of fibers, collagen, and other structures within the tissue. In the regions infiltrated by gliomas, the original structure of brain tissue is destroyed, the invading cancer cells decompose and reduce the expression of myelin, and the birefringence changes are weak. Compared with intensity images, polarization images exhibit higher contrast, providing a direct display of the distinctions between gliomas and normal tissue, making it easier to diagnose in clinical settings.Our preliminary study only used a limited number of mice. More samples and glioma tissues at different stages will be further studied in the future study. In addition, efforts will be made to investigate in vivo animal samples and ex vivo human specimens, aiming to promote the application of PS-OCT in the identification and resection of glioma in neurosurgery of the brain.ConclusionsOur results demonstrated that en-face images reveal structural information in the mouse brain, including the cerebral cortex, internal capsule, and hippocampus. Using polarization parameters of phase retardation and optic axis, the position and orientation of internal structures like the internal capsule and nerve fiber bundles with birefringent tissues can be clearly observed. The originally symmetric structure in the brain of tumor mice is destroyed, with erosion of the cortical edge and only partial visibility of internal fiber structures. Optic axis standard deviation proves effective in distinguishing between normal and glioma mouse brains. This study proves that high-resolution PS-OCT is promising to monitor the infiltration process of glioma through changes in birefringent tissues such as nerve fiber bundles.

ObjectiveCorneal laser refractive surgery is a method for correcting vision using lasers to reshape the cornea and change its curvature and thickness. Femtosecond laser corneal cutting is widely used in ophthalmic refractive surgery as a precise, minimally invasive, and controllable surgical technique. In femtosecond laser refractive surgery, the numerical aperture of the optical system determines the focal spot size and required single-pulse energy, which are critical parameters that influence the corneal cutting quality. In this study, we built a femtosecond laser surgery system with an adjustable numerical aperture. We investigated the effect of numerical aperture on cutting quality in the corneal stroma by analyzing the differences in bubble morphology, smoothness of flap separation, and proportion of damaged stromal cells. This study aimed to assist clinicians in selecting the appropriate surgical parameters more effectively.MethodsFreshly enucleated pig eyeballs and New Zealand white rabbits were selected as experimental subjects. By adjusting the diameter of the incident beam, corneal flaps were formed on the pig eyeballs using a femtosecond laser with numerical aperture values of 0.16, 0.30, and 0.80. The morphology of the bubbles after cutting was recorded, and the smoothness of the separation was observed when the corneal flaps were lifted. Cell damage experiments were conducted by cutting New Zealand white rabbit eyeballs with a femtosecond laser at numerical aperture values of 0.16, 0.30, and 0.80. After creating the flap with the femtosecond laser, the rabbit eyeballs were placed in corneal active medium (DX solution) and incubated at 4 ℃ for 6 h to induce apoptosis in the damaged corneal stromal cells. Subsequently, the rabbit eyeballs were removed and prefixed in a 4% paraformaldehyde (PFA) solution for 2 h. After dewaxing and rehydration, the corneal sections were double-stained with DAPI (4,6-diamidino-2-phenylindole, D9542, Sigma-Aldrich) and TUNEL (TdT-mediated dUTP nick end labeling, C1088, Beyotime). Finally, the apoptotic cell counts were determined by imaging the sections under a fluorescence microscope.Results and DiscussionsUnder the three different numerical aperture values (0.16, 0.30, and 0.80), as the numerical aperture increases, the volume of the bubbles decreases gradually, and the density of the bubble layer increases (Figs.5 and 6). This is mainly attributed to the decreasing volume of the focal spot with an increasing numerical aperture, which decreases cavitation bubbles. Corneal flaps formed at a higher numerical aperture are easier to separate. This is primarily because smaller cavitation bubbles result in a denser bubble layers, which facilitates the separation of the interlamellar space with less adhesions between the tissue layers. In the cell damage experiment, as numerical aperture increases, the number of apoptotic cells decreases significantly, as shown in Fig. 7. This is attributed to the decreased single-pulse energy and decreased focal spot size associated with an increase in numerical aperture, which results in smaller photodisruption zones and reduced damage to the surrounding tissues. Therefore, increasing the numerical aperture is beneficial for reducing the extent of stromal cell damage.ConclusionsThe effects of femtosecond laser corneal cutting for different numerical aperture values were investigated experimentally. The morphological differences in cavitation bubbles induced by a femtosecond laser at different numerical aperture values were analyzed, and the ease of separation of the lamellar layers and the extent of cell damage were compared. The results of the experiment show that during femtosecond laser corneal cutting, a higher numerical aperture yields smaller bubbles, denser bubble layers, easier separation of corneal flaps, and lower levels of damage to stromal cells. Therefore, a higher numerical aperture is beneficial in femtosecond laser refractive surgery. Overall, this study provides valuable insights into the effects of numerical aperture on femtosecond laser corneal cutting and highlights the importance of optimizing the numerical aperture to achieve improved treatment outcomes in corneal procedures.

ObjectiveLong-term cellular imaging and analysis are pivotal for biomedical research and clinical diagnosis. Effective and continuous nanoscale imaging of living cells reveals natural, dynamic, and subcellular alterations at the microscale, which are crucial for understanding long-term cellular morphology and metabolism. Interferometric spectroscopy, which has garnered considerable attention for molecular detection, elucidates nanoscale fluctuations on the sample surfaces. This technology dispenses with the need for precise instruments for generating analytically coherent signals or costly optical setups. The algorithmic reconstruction of the collected interferometric spectral data yields quantitative imaging outcomes. Furthermore, it obviates the reliance on the lens selection ability of the microscope objective, thereby allowing space for the integration of microcell culture devices. Consequently, interferometric spectroscopy analysis has emerged as a highly promising method for addressing the extant challenges in the in situ analysis of unlabeled live cells. A hyperspectral interferometric imaging system for long-term in situ analysis of unlabeled live cells is introduced in this paper, facilitating the quantitative imaging of nanostructures and measurements of the dry mass. Moreover, the system is employed in investigating the quantitative nanostructure and dry mass dynamics of various cells throughout the entire cell cycle, which showcases a potential application of the proposed method and system in the biomedical realm.MethodsThe coherent signals generated by light reflected from a substrate and the scattered light within a cell provide valuable insights into the three-dimensional structure and dry mass distribution of the sample. A pivotal innovation in this study is the proposal for a label-free quantitative microscopy imaging technique for hyperspectral interferometric reconstruction. By formulating a mathematical model to characterize the interferometric signal, a sample quantitative reconstruction algorithm was devised, enabling the acquisition of quantitative nanostructures and the dry mass distribution of live cells. In the methodology section, we first establish a hyperspectral interference model for adherent cells on silicon wafers, and subsequently propose a label-free quantitative imaging approach based on this model. The phase distribution in the spatial domain, derived from the reflection spectrum containing the interference information, was converted into refractive index and dry mass information. Subsequently, a microscopic imaging system for hyperspectral interference is introduced. Unlike conventional wide-field optical microscopes, this system features a fiber-optic spectrometer structure for hyperspectral imaging. Additionally, a two-dimensional scanning platform with sub-nanometer-level step accuracy was positioned beneath the sample, facilitating point-by-point scanning with a minimum step of 0.16 nm. An integrated live-cell culture incubator was incorporated into this system. Unlike conventional microscope-equipped incubators, the incubator in this system included a liquid delivery function. Finally, a comprehensive overview of the microscale in situ live cell culture device is provided and the performance of the incubator is demonstrated.Results and DiscussionsMicroscopic imaging and hyperspectral interferometric reconstruction imaging of processed three-dimensional silica photon and individually cultured HeLa cells (Fig.5) are demonstrated in this study. The interferometric reconstruction exhibits a thickness error of merely 1.27 nm, accurately restoring the three-dimensional structure of the phantom. Each pixel achieves a dry mass measurement accuracy of 25.75×10-18 g. Moreover, quantitative imaging of the entire cell cycle of HeLa cells and HCerEpiC cells is conducted with a comparison of the stem mass changes between the two cell types (Fig.6). Subsequently, the nuclear-to-cytoplasmic ratios of the two different cell types throughout the cell cycle are determined. Notably, the nuclear-to-cytoplasmic ratio of HeLa cells increases to 24.45% compared with 16.27% in HCerEpiC cells, indicating a relatively higher proportion of nuclear dry mass. The lateral resolution of the imaging system is 708.1 nm, and the axial resolution can achieve 91.89 nm. The complete spectral data of a single cell can be obtained in approximately 1.5 min.ConclusionsAs the fundamental building blocks of life, cells hold significant importance across various application domains, including in clinical medical diagnosis, life science research, and basic medical investigations. However, high-resolution measurement techniques such as electron microscopy, near-field optics, and stochastic optical reconstruction microscopy, as well as separation and purification methods such as chromatography, mass spectrometry, and spectrophotometry, are not conducive to in situ real-time measurements of live cell cultures. The novel hyperspectral white-light interference live-cell microscopy imaging technology proposed in this study captures interferometric hyperspectral data from samples, accomplishes three-dimensional reconstruction using an algorithmic design, and constructs a corresponding automated integrated instrument. This instrument comprises a reflective optical microscopy imaging setup, an interference spectrum acquisition and processing module, a sample nanoscale precision scanning module, and a live cell culture module. To some extent, it addresses the limitations of current measurement techniques and achieves the objective of simultaneously acquiring the quantitative nanostructures and dry mass distribution of live cells. The self-reflective interference structure employed by the system eliminates the need for intricate optical modulation components, exhibiting a straightforward design and convenient operation, thereby introducing a novel imaging approach to the biomedical field.

ObjectiveThe rupture of vulnerable plaques caused by atherosclerosis has become one of the most serious threats to human health. Intravascular optical coherence tomography (IVOCT) can accurately identify vulnerable plaque characteristics, such as thin-cap fibroatheroma plaques, owing to its high resolution, and has gradually become the gold standard for the diagnosis of vulnerable plaques. Typically, clinicians must manually mark the location of plaques in an image based on their experience. However, this method is time-consuming and labor-intensive and is susceptible to the subjective assessment of the clinician. Manual interpretation significantly reduces the speed and precision of vulnerable plaque diagnosis. Some studies based on traditional machine learning have been conducted for the detection of vulnerable plaques and have achieved the classification of single-frame images. However, the accuracy of frame-level information is insufficient to assist clinicians in determining treatment strategies. These methods require a second interpretation by clinicians. This study proposes an evaluation algorithm for vulnerable plaque identification in IVOCT images based on an improved Faster R-CNN (regional convolutional neural network) framework. In addition to accurately locating vulnerable plaques, the algorithm can quantitatively assess the risk of plaque rupture, providing diagnostic suggestions to clinicians and assisting in the formulation of treatment plans. The comprehensive nature of this approach is expected to play an important role in improving the efficiency and precision of vulnerable plaque diagnosis.Methods This study is divided into two partsautomatic identification of vulnerable plaques and assessment of vulnerable plaque rupture risk. To identify vulnerable plaques based on the Faster R-CNN, this study proposes an improved strategy for enhanced cyclic shift data, (X, W) encoding BBox, and the introduction of additional semantic segmentation heads according to the characteristics of IVOCT images. The network is generally divided into four parts (feature extraction, region extraction, secondary detection, and A-scan classification), allowing the network to locate vulnerable plaques with higher accuracy. In this study, the angle of accumulation of the lesion, the thickness of the fibrous cap, macrophage infiltration, superficial microcalcification, and vascular stenosis degree of vulnerable plaques are selected as indicators to assess the risk of rupture. The vascular lumen area is used to characterize the degree of vascular stenosis in vulnerable plaques; the smaller the lumen area, the more severe the stenosis. Furthermore, an adaptive threshold method is designed to calculate the thickness of the fibrous cap, which is considered thin when the thickness is less than 65 μm. The risk of plaque rupture is indicated by a lesion accumulation angle greater than 90°, and a polar graph is used to measure the lesion accumulation angle. To identify superficial microcalcifications and macrophage infiltration, features are extracted from the images and reclassified. The application of these methods makes our study more comprehensive and accurate.Results and DiscussionsThe proposed method is trained and tested using the public dataset CCCV2017 IVOCT. This study presents the results of the ablation experiment for Faster R-CNN (Table 2). The improved network performs well in positioning vulnerable plaques, with mAP50 increasing to 0.744 and the Dice value increasing to 0.905. Compared with weakly supervised detection (WSD) and salient-region-based convolutional neural network (SRCNN) methods, the method proposed in this study significantly improves the recall and Dice values (Table 3). The intersection of union (IOU) value of the lumen area is 0.9445, and the prediction result is consistent with actual result of the lumen area [Fig.7(c)]. The root mean square error RMSE and the goodness of fit R2 are used to verify the feasibility of the calculation of the thickness of the fiber cap, and the test results are 1.17 pixel and 0.62, respectively. After positioning the region accurately, the cumulative angle of the lesion is also accurately assessed [Fig.7(d)]. To evaluate the performance of the model in predicting superficial plaque microcalcifications and macrophage infiltration, a comprehensive analysis is performed using a confusion matrix [Figs.7(e) and (f)]. These results demonstrate that the proposed method achieves satisfactory results for multiple evaluation metrics and provides a reliable solution for the identification of vulnerable plaques and rupture risk assessment.ConclusionsIn this study, the cyclic shift, (X, W), and encoding BBox are added, and additional semantic segmentation heads are introduced to the Faster R-CNN network to improve the detection performance for vulnerable plaques. Compared to the initial network and adding only a single change, the method proposed in this study significantly improves the mAP50 and Dice values of the network. Compared with WSD and SRCNN, our method also achieves significant improvements in the recall rate and Dice value. Furthermore, to obtain accurate location results for the vulnerable plaque region, the angle of the plaque region is used to measure the angle of accumulation of the lesion, and the cumulative pixels of the fiber cap are used to calculate the thickness of the fiber cap. Deep neural network features combined with gradient direction histogram features are used to analyze macrophage infiltration and superficial microcalcification, and the vascular stenosis degree is evaluated in the lesion lumen region. Multiple single-evaluation results are used to measure the risk of rupture of vulnerable plaques. The comprehensive method proposed in this paper achieves a significant breakthrough in vulnerable plaque detection and provides more comprehensive and reliable data support for clinical diagnosis in terms of rupture risk assessment.

ObjectiveWearable flexible electronics is one of the development trends in medical-health monitoring, particularly cardiovascular-disease monitoring. Pulse wave is an important source of information for assessing cardiovascular health; however, it is a non-stationary weak signal and imposes high requirements on the sensitivity and stability of detection. To solve the key technical problems of wearable health monitoring, a graphene-based flexible pressure sensor with a multilevel branched microstructure is designed and developed in this study, which significantly improves the sensing performance of pulse waves and forms the foundation for a wearable flexible pressure sensor. The sensing health-monitoring system is developed using a sensing-like cuffless blood-pressure-monitoring algorithm based on single-point radial artery pulse waves. The prediction errors of the system for human systolic blood pressure (SBP) and diastolic blood pressure (DBP) are (0.7±10.5) mmHg and (0.5±6.1) mmHg, respectively. The findings of this study can provide important technical support for cardiovascular health-monitoring systems and application research, as well as for wearable precision medical-health monitoring.MethodsFlexible pressure sensors based on array structures exhibit key technical issues such as difficulty in achieving high sensitivity and a wide pressure-detection range, as well as limited usage. Hence, a hierarchical branch (HB) structure pressure-sensor design scheme is proposed in this study to improve the performance of array-microstructure pressure sensors. First, we completed the design of the HB structure via finite-element analysis. Results of the finite-element analysis reveal the unique effect of the HB structure: it not only includes the elastic-modulus- reduction effect caused by the superposition of multiple elastic layers but also integrates the pressure-diffusion effect caused by the HB structure, thus realizing the gradual activation and further strengthening of the active-layer conduction path. As such, the deformation range of the elastic layer (sensor pressure-detection range) and the deformation sensitivity to pressure (sensor sensitivity) can be improved. To solve the problem wherein the existing blood-pressure-detection equipment requires cuff pressurization and continuous blood-pressure monitoring cannot be achieved easily without pressurization interference, we construct a cuffless blood-pressure detection model, the class-aware model based on the Moens-Korteweg (M-K) equation and Transformers (the CAMKformer model). This model incorporates the idea of ​​cascade learning, uses the basic formula for blood-pressure calculation based on pulse-wave conduction velocity as the principle, and applies the Transformer model to classify the input pulse wave for blood pressure, thus forming a two-stage cuffless blood-pressure detection model. Compared with conventional machine-learning algorithms based only on formulas or tree models, this model combines formula-related features with original pulse-wave data, where the complex feature-extraction capabilities of deep-learning models and the strong interpretability of theoretical models are fully utilized. In addition to affording high robustness, it integrates multimodal blood-pressure related information (discrete pulse-wave characteristics and continuous pulse-wave data), thus significantly reducing the blood-pressure detection errors inherent in conventional research methods.Results and DiscussionsExperimental results show that the HB structure enables flexible pressure sensors based on array microstructures to simultaneously improve sensitivity (an increase by 14 times, which is more significant than that of previously published single-layer structure strategies) and the linear range (Fig.6). Additionally, the HB structural strategy based on template and multilayer superposition methods offers significant advantages in terms of structural uniformity, adjustability, and scalability. For example, molds can be fabricated via highly controllable processes (such as photolithography), thus allowing parameters such as structural shape and size to be adjusted. We believe that the HB strategy can be used as a general strategy to adjust mechanical-stress transfer and optimize sensor performance, as well as exhibits broad application prospects in sensor design. A diverse database can further demonstrate the robustness and generalizability of the CAMKformer model. The results show that the wearable system and CAMKformer model constructed in this study can adapt promptly to the pulse-wave characteristics of different individuals and accurately detect human SBP and DBP [with errors of (0.7±10.5) mmHg and (0.5±6.1) mmHg, respectively, as shown in Table 3]. Different from the pressurized blood-pressure monitoring method of conventional electronic sphygmomanometers and commercial blood-pressure measurement smart watches, the abovementioned system does not require pressure application to the user’s radial artery to detect blood pressure; hence, it is suitable for continuously measuring the user’s blood pressure during daily activities or at night, as blood pressure changes during sleep. In addition, this model uses a single-cycle pulse wave as input, presents a simple system configuration, and is highly flexible for use.ConclusionsIn this study, wearable flexible electronic technology and medical-health monitoring are adopted as the research background. The requirements of wearable cardiovascular health monitoring are identified, and the associated principles, devices, systems, and application levels are investigated systematically. First, a design scheme for a HB structure flexible pressure sensor is proposed, and a graphene HB structure flexible pressure sensor is reconstructed simultaneously with a pulse-wave measurement system. Experimental results show that the bionic HB structure strategy enhances the sensitivity (an increase by 14 times) and linear range (4.6 times expansion) of the array-based microstructure pressure sensor, thus enabling distortion-free and accurate measurements of pulse waves. Subsequently, a class-aware cuffless blood-pressure-detection model is established. This model, which is based on the abovementioned flexible pressure sensor, obtains single-point pulse waves of the radial artery. Additionally, it uses a deep-learning model based on the Transformer for blood-pressure classification and a theoretical model based on the M-K equation for blood-pressure prediction. Compared with conventional machine-learning algorithms based only on formulas or tree models, this algorithm combines commonly used pulse features with original pulse-wave data, where the complex feature-extraction capabilities of deep-learning models and the strong interpretability and robustness of theoretical models are fully exploited. Owing to its high stickiness, it realizes the fusion of multimodal pulse-related information and significantly reduces the error of cuffless blood-pressure detection [the errors are (0.7±10.5) mmHg and (0.5±6.1) mmHg for SBP and DBP, respectively], thus satisfying the international standards for non-invasive blood-pressure monitors. The cuffless blood-pressure monitoring system proposed herein is devoid of external pressure interference. Additionally, it is expected to transform the blood-pressure dynamic detection mode from “single-point, high-dispersion transient detection” to “multipoint, low-dispersion online monitoring,” thus facilitating users or doctors in dynamically monitoring blood-pressure changes to achieve early proactive screening of hypertension and improve hypertension early-warning and monitoring capabilities.

ObjectiveThe structural characteristics of biological tissues can provide essential information for diagnosing clinical diseases. Medical imaging methods, such as X-ray imaging, computed tomography, magnetic resonance imaging, positron emission tomography, and ultrasound imaging, can obtain the structure and function of the tissues; however, these methods cannot detect small lesions due to low imaging resolutions. A biopsy, the gold standard for tumor diagnosis, is painful and invasive, and some tissues cannot be sampled. Optical coherence tomography (OCT) is a label-free, noninvasive, three-dimensional optical imaging method with micrometer resolution and is used for optical biopsy. In the traditional benchtop OCT system, the large scanning probe fixed on a bench cannot reach into a narrow cavity, and the detection process requires a high degree of patient cooperation. Therefore, the use of benchtop OCT systems for clinical applications is limited to a certain extent. A handheld OCT system has a separated sample arm packaged into a miniaturized handheld probe, which is connected to the main OCT system via an optical fiber. The miniaturized probe can be held conveniently and inserted into the narrow cavity, increasing the applicability and flexibility. We propose a video-guided handheld high-speed OCT system with an A-line speed of 200 kHz. The compact handheld probe is easy to hold and can be inserted into narrow cavities. A camera integrated into the probe can capture real-time video for guiding OCT imaging. An image registration method is also developed to eliminate image misalignment due to hand tremors during OCT imaging.MethodsA handheld OCT system based on a swept source was built for tissue imaging, as shown in Figure 1. The handheld probe was connected to the main system through an optical fiber. The handheld probe was made to have a smaller size and lower power consumption by employing a microelectromechanical system-based scanner for beam scanning. A visible imaging camera integrated inside the handheld probe allows for real-time imaging, facilitating rapid localization of the region of interest, and guiding OCT imaging. The system has a high scanning speed with an A-line rate of 200 kHz, a lateral resolution of 31.4 μm, and an axial resolution of 5.2 μm in tissue. To improve the image quality, an image registration method was developed to eliminate image dithering. The handheld OCT system was validated using ex-vivo porcine cornea and tooth. The images obtained by the handheld OCT system were also compared with those obtained by the benchtop OCT system.Results and DiscussionsThe ex-vivo porcine cornea and tooth were imaged using the handheld OCT system, as shown in Figure 2. Figures 2(a) and 2(d) show the images of the cornea and tooth, respectively, captured by a cell phone. Real-time videos can be captured to guide the imaging location and determine the region of interest using the camera in the handheld OCT system. The images of the cornea and tooth captured by the video camera are shown in Figures 2(b) and 2(e), respectively. Single B-scan images of the cornea and tooth are captured by the handheld OCT system, as shown in Figures 2(c) and 2(f), respectively. The results show that the handheld OCT system can acquire high-resolution cross-sectional structural images for the cornea and tooth. During imaging using the handheld probe, the hand tremor causes OCT image misalignment, and image registration is required. Figure 3 shows the OCT images of the porcine cornea and tooth with/without image registration. After multiple rounds of B-scanning at the same location, the images were averaged, as shown in Figures 3(a) and 3(c). The averaged images are blurry, showing image misalignment. After image registration, the image misalignment is corrected, and the averaging B-scan images present a clear tissue structure, as shown in Figures 3(b) and 3(d). To evaluate the imaging performance, the images obtained from the handheld OCT system were compared with those from the benchtop OCT system, as shown in Figure 4. Figures 4(a) and 4(b) show the single B-scan images of the ex-vivo porcine tooth from the benchtop and handheld OCT systems, respectively. The results show that there are no significant differences between the images acquired by the two systems. The CNRs of the images from the handheld and benchtop OCT systems are 3.28±0.01 and 3.30±0.02, respectively. As there is no image misalignment during imaging using the benchtop OCT system, it can provide a reference for evaluating the image registration method. After image registration, the averaging B-scan images from the handheld OCT system show a structure similar to that of the images from the benchtop OCT system. Moreover, the registered images from the handheld OCT system have a quality similar to that of the images from the benchtop OCT system.ConclusionsIn this study, a video-guided high-speed handheld OCT system with an A-line scanning rate of 200 kHz is designed and constructed. Compared with the traditional benchtop OCT system, the handheld system has a compact and easy-to-hold handheld probe, which extends the applications and increases the flexibility of OCT imaging. A video camera inside the probe allows real-time imaging to quickly localize the region of interest and guide the OCT image. An image registration method can eliminate image misalignment during OCT imaging. The imaging performance of the system was verified by imaging ex-vivo porcine cornea and tooth. The results show that the handheld OCT system can provide a more convenient method for tissue imaging, thus exhibiting great potential for imaging the tissues in a narrow cavity and serving the needs of less-cooperative patients.

ObjectiveVascular imaging is crucial for medical diagnosis, and it facilitates disease diagnosis, disease progression monitoring, surgical planning and navigation, and patient prognosis evaluation. However, conventional imaging methods encounter challenges in rapid and noninvasively imaging of superficial blood vessels because of the similarities in texture and color with surrounding tissues. In clinical surgery, preoperative superficial vascular imaging and intraoperative vascular display are beneficial for reducing bleeding, facilitating surgical navigation and path planning, and promoting postoperative blood supply recovery.MethodsA fluorescent imaging system in the second near-infrared window (NIR-II) to capture images of the forearm vascular network in patients was used in this study. The research involved 12 patients, with indocyanine green serving as a contrast agent for obtaining NIR-II images of the forearm blood vessels. These images were used to observe the anatomical structure of the venous vascular network. Furthermore, computer-aided analysis was employed to improve image quality, support surgical path planning and prognosis prediction, and provide valuable guidance for clinical practitioners.Results and DiscussionsHigh-resolution and high-contrast images are captured using NIR-II fluorescence angiography. The clarity of these images are enhanced using artificial intelligence techniques. Computer simulation was employed to simulate venous network reflux. The agreement between the measurement results obtained from this technique and ultrasound was evaluated using the Bland Altman plot and consistency measurements.ConclusionsThe acquired images are used to examine the anatomical structure of the venous vascular network and combined with blood flow simulation. This integration aims to assist clinicians in determining optimal surgical trajectories and predicting outcomes. The application of NIR-II fluorescence imaging and computational simulation techniques has potential in providing valuable support for surgeons in performing various vascular procedures in the future.

ObjectiveNucleic acid detection methods enable the rapid identification of specific genetic indicators. However, their extensive application is limited by the sequential use of multiple instruments and the high technical requirements for operators. A fully integrated nucleic acid analysis system can automate the sample-to-answer detection process. However, nucleic acid amplification via PCR technology is time-consuming, and stringent requirements are placed on temperature control accuracy and heating/cooling speed, which increases the manufacturing cost of the corresponding instruments. These systems also lack the flexibility to accommodate variations in sample preprocessing methods and nucleic acid extraction protocols for different types of clinical samples. To address these challenges, we present a novel, fully integrated nucleic acid analysis system that contains a syringe-based sample processing and nucleic acid extraction module, a fully enclosed PC-based multiplexed detection microfluidic chip, and a nucleic acid amplification product detection module. We applied this system for the precise medical testing of various pathogenic infections in gynecology. The results indicate that our system can achieve precise medical molecular diagnosis with the fully integrated automation of a micro-nano reaction system, as well as speedy processing, high sensitivity and specificity, and multiplexed parallel detection. The system also shows potential applications in the in vitro identification of genetic and other nucleic acid-related diseases, holding significant social and economic value for the prevention and control of major diseases in China.MethodsThis paper presents a fully integrated nucleic acid analysis system based on a syringe microfluidic chip. The system consists of two modules. The first is an automated syringe nucleic acid extraction module that accommodates multiple nucleic acid extraction techniques based on different clinical sample types. This process involves four primary steps: sample loading, incubation, washing, and lysis by heating and shaking. The second module is an isothermally amplified nucleic acid detection module capable of simultaneous multivariate detection. The nucleic acid amplification and detection platform, based on microfluidic technology, includes a disk-based microfluidic chip that serves as a nucleic acid isothermal amplification carrier, a temperature control platform ensuring precise isothermal amplification of nucleic acids, a fluorescence detection platform for real-time monitoring of nucleic acid amplification, and a software analysis platform for controlling and analyzing the entire system. The two modules perform their respective functions independently and can also be combined into an integrated syringe-microfluidic chip nucleic acid analysis system, forming a fully integrated micro-nano detection platform that rapidly automates both nucleic acid extraction and detection and is capable of detecting multiple indicators in parallel.Results and DiscussionsThe fully integrated system was evaluated using a standard Candida tropical culture strain and 64 clinical swab samples obtained from patients with vulvovaginal candidiasis. The results show that the detection concentration threshold of 3.95×102 CFU/mL was comparable to that of the conventional nucleic acid detection method, which involves extracting nucleic acid with a reagent kit and amplifying it on a commercial PCR machine. The sample preparation is more convenient and fast, with only one sample loading step, and nucleic acid extraction takes 10 min, resulting in significant time and labor savings (Table 1). A chi-square value of 1 and a Kappa value of 0.950 indicate a strong correlation with the gold standard method of clinical microbial culture (Table 2). Although a false-negative result with two samples containing Candida albicans was obtained, optimizing the primer sequences and reaction systems for isothermal amplification can address this problem. Therefore, this comprehensive integrated nucleic acid detection platform provides rapid and accurate multiplexed detection for the diagnosis of clinical microbial pathogen infections and has advanced technological capabilities.ConclusionsIn this study, a fully integrated nucleic acid analysis system based on a syringe microfluidic chip is developed, which consists of two modules. One is an automatic syringe nucleic acid extraction module, and the other is an isothermally amplified nucleic acid detection module based on a microfluidic chip. The system was tested using a standard Candida tropical culture strain and 64 clinical swab samples of vulvovaginal candidiasis. The results show that the minimum detection concentration of the bacterial solution in the system is 3.95×102 CFU/mL, and a more convenient and rapid sample preparation is achieved with only one sample loading step with a nucleic acid extraction duration of 10 min. Compared with the gold standard culture method, a chi-square test and Kappa value of 1 and 0.950, respectively, indicate that there is no significant difference between the two methods, with high consistency. The syringe-microfluidic chip-based, fully integrated nucleic acid analysis system detailed in this study provides a reliable platform for the rapid detection of nucleic acids using multiple indicators in a micro-nano system. The system offers precise detection and convenient analysis and supports applications in clinical medicine, grassroots screening for infectious diseases, health prevention programs, and basic biomedical research. This underscores the significance of this system in molecular diagnostics with in vitro precision in clinical settings, such as genetic disease identification and tumor molecular marker co-detection, as well as its potential uses in food safety and preventive healthcare applications.

ObjectiveRespiratory viruses possess strong infectivity, rapid transmission, short incubation periods, and sudden onset of illness. These features have led to widespread global transmission, significantly affecting the health of children worldwide. In addition, these viruses have caused significant economic losses and casualties in various countries. Antibiotics are commonly used to control respiratory infections in humans. Therefore, accurate and rapid understanding of the course of respiratory infections is the foundation for selecting a treatment plan.In biomedical imaging, various imaging methods can reveal microscopic and macroscopic phenomena within organisms. These methods include magnetic resonance imaging (MRI), computed tomography, positron emission tomography, ultrasound (US) imaging, optical coherence tomography, and fluorescence imaging. These technologies provide rich information, thereby contributing to a comprehensive understanding of the characteristics of respiratory infections and supporting the development of rational treatment plans. Owing to limitations in specificity, resolution, and radiation, these imaging techniques lack the ability to accurately image biological structures in the early stages of disease development. In this study, the noninvasive, deep-penetrating, and high spatial resolution advantages of photoacoustic (PA) imaging (PAI) are utilized. This is combined with the excellent fluorescence properties of the exogenous contrast agent indocyanine green nanoparticles (nano-ICG) in the near-infrared region and the high expression of macrophages during inflammation. This combination enables the visualization of the development of respiratory inflammation.Through the establishment of animal models and in vivo experiments, we quantitatively evaluate the macrophage expression in acute respiratory infections, as shown in Fig.1. Research on PAI is expected to provide a new approach for the noninvasive quantitative assessment of inflammation in acute respiratory infections.MethodsThis study uses a respiratory inflammation mouse model for photoacoustic imaging. Initially, the mice are anesthetized using isoflurane with volume fraction of 1.5%, followed by the instillation of lipopolysaccharide (LPS) solution into the mouse respiratory tract to construct the respiratory inflammation model group after two days. Five mice are selected from the Control and Model groups for further studies. Subsequently, the ultraviolet absorption spectra and cytotoxicity of nano-ICG materials are studied under irradiation at different wavelengths. The internalization dynamics of macrophages after nano-ICG injection are investigated. Finally, a PA-US dual-mode small animal imaging system is used to image different groups (Control and Model groups). Imaging is conducted before nano-ICG instillation and when the post-injection time is 15, 30, and 60 min in each group of mice. PA and US data collected from the experiment are subjected to offline quantitative analysis using Vevo Lab Software 3.2.0 to observe the overall respiratory inflammation under PAI.Results and DiscussionsTransmission electron microscopy is used to characterize the shape and size of the exogenous contrast agent, nano-ICG. As shown in Fig.2 (a), Nano-ICG has an average size of approximately 65 nm with a round shape and aggregated distribution. Subsequently, the cell counting kit is employed to evaluate the in vitro viability of macrophages, and the absorbance of each well is determined using enzyme-linked immunosorbent assay, as shown in Figs.2(b) and 2(b). The internalization of nano-ICG at different time points after injection is observed using confocal fluorescence microscope, as shown in Fig.3. These results indicate that nano-ICG continue to be internalized by the macrophages within one hour after injection. Additionally, laser confocal microscope images exhibit a positive correlation between the uptake of nano-ICG by macrophages and time. After engulfing the nanoparticles, the imaging effect of macrophages becomes more prominent. Within the first 15 min after nano-ICG injection in mice, Model group exhibits an enhanced trend in the PA signal compared with the normal group. In Control group, the PA signal of nano-ICG exhibits a decreasing trend over time, whereas in Model group, the corresponding PA signal continues to increase. After 30 min, the PAI images of Control and Model groups exhibit more noticeable contrast. After 60 min, Model group exhibits the strongest PA signal, showing a more significant contrast than Control group, as shown in Fig.4(a). In Control group, the amount of nano-ICG in the mouse airways continuously decreases with increasing post-injection time, as shown in Fig.4(b). In Model group, the quantity of nano-ICG on the mouse airway wall increases continuously with the post-injection time, as shown in Fig.4(c). These results indicate that nano-ICG can effectively reflect the degree of development of inflammatory cells on the respiratory wall when the post-injection time is 60 min. Three-dimensional PAI images of respiratory inflammation provide more accurate information on respiratory wall inflammation, as shown in Fig.5(a). The coronal images generated by two-dimensional PAI scans, indicate the presence of inflammatory cell aggregation in the respiratory tract at that position. Figure 5(b) validates the accuracy of three-dimensional PAI images by showing images of inflammatory and non-inflammatory cells in the respiratory tract using an in vivo imaging system (IVIS) for small animals. Although PAI can visually present respiratory inflammation, some mice must be euthanized for pathological sectioning and staining to gain a more comprehensive understanding of the morphological and structural changes in inflammation. Histological results are shown in Fig.6. Control group sections exhibit a light pink color in the airways with no thickening on the inner side of the tube wall and smooth and regular surfaces without apparent lesions. In contrast, Model group sections exhibit noticeable bleeding, significant swelling, scattered bleeding points on the surface, infiltration of inflammatory cells on the inner side of the tube wall, and increased secretion into the lumen, consistent with the imaging structures of PAI.ConclusionsThis study successfully establishes a mouse model for acute respiratory inflammation and utilizes nano-ICG to observe respiratory inflammation, confirming the feasibility of evaluating inflammation using PAI. The PAI results for inflammation in the model are consistent with the pathological and IVIS results. This research provides new methods and insights for assessing respiratory inflammation. In summary, PAI is widely applicable to respiratory inflammation research because of its unique imaging capabilities, non-invasiveness, and high resolution. This study provides strong support for a deeper understanding of the development of respiratory inflammation and evaluation of treatment effectiveness.

ObjectiveCurrently, most commercial optical coherence angiography (OCTA) systems lack a real-time display of en face OCTA images, which makes it difficult for operators to obtain intuitive feedback on data quality and adjust the system quickly and accurately in a single acquisition of OCTA volume data. In the process of dynamic acquisition of OCTA volume data, determining the state changes of the subjects is difficult, resulting in invalid data acquisition. In an experiment on flicker light-induced functional retinal hyperemia, which provides a new perspective for the early screening of human diabetic retinopathy, the continuous collection of multiple groups of three-dimensional data may be invalid because of the poor quality of one group, thereby wasting data processing time. Therefore, a real-time display of the experimental results is required. Although GPU-based OCTA data real-time processing methods have been proposed, the speed of the existing real-time processing methods still needs to be improved to adapt to high-speed scanning OCTA systems.MethodsIt is developed on a spectral-domain OCT (SD-OCT) system. Limited by the frame grabber, the maximum acquisition line speed of the system was 120 kHz in the high-bit-depth mode and 250 kHz in the low-bit-depth mode. An optical coherence angiography algorithm based on the inverse signal-to-noise ratio (SNR) and complex-valued decorrelation (ID-OCTA) was used to extract blood signals by adaptive SNR and achieve high-quality angiography. The sum of absolute differences (SAD) algorithm was used to register OCT images, and the retinal OCT images were segmented by a vertical gradient distribution, which is convenient for fast parallel processing on a Graphics Processing Unit (GPU). This study proposes a real-time processing framework based on a GPU (Fig.1), which uses texture memory to realize fast interpolation and filtering calculations and the CUDA stream to mask the time delay of data transmission between the host and GPU. We developed a real-time processing program using C++ and CUDA and a multithread system control program using the C++ and MFC libraries. To compare the guiding effect of the real-time data processing method in this study and the method using only a CPU, two real-time display modes were used for data acquisition: en face OCTA images and cross-sectional OCT images. Moderately experienced operators collected multiple groups of data in these modes within 40 s. Three sets of data were collected continuously in 12 s to simulate the dynamic acquisition of OCTA volume data. The quality of the collected data was evaluated using the en face OCTA image quality index. In the flicker light-induced functional retinal hyperemia experiment in mice, the experimental success criteria and quantification parameters were set. Operators conducted multiple experiments to compare the experimental success rates of the two real-time display modes.Results and DiscussionsThe en face OCTA image real-time display was realized in the system with a 250 kHz line scanning speed (Fig.2), and the line-processing rate was 365 kHz (Table 1). Compared with the real-time display of the cross-sectional OCT image, the real-time en face OCTA image can guide system refraction and eye position adjustment more accurately and quickly (Fig.3, Table 2). In dynamic OCTA acquisition, the real-time display of en face OCTA images can reflect the movement of the mouse eye and its jitter, which is not evident in cross-sectional OCT images (Fig.4). In an experiment on functional retinal hyperemia, the real-time display video generated immediately after the experiment (Fig.6) can be used as a preview of the experimental results. Compared with 66.7% in the cross-sectional OCT image real-time display mode, the experimental success rate of the en face OCTA image real-time display mode was 93.3%, which proves that this mode helps avoid the situation where system adjustment and subject status problems lead to experimental failure (Table 3, Fig.5). The system can help the experimenter screen unqualified data and quickly judge the experimental results. In the future, the system could replace the frame grabber that supports a higher acquisition speed to improve its scanning speed.ConclusionsWe realized the real-time display of en face OCTA images in a 250 kHz SD-OCT system. Compared to the real-time display of cross-sectional OCT images using a CPU, the real-time display method in this study helps the operator adjust the system more quickly and accurately during the single acquisition of OCTA volume data and provides feedback on the subject eye state during the dynamic acquisition of OCTA volume data. The proposed real-time display method was confirmed to have a data quality feedback function in the experiment of flicker light-induced functional retinal hyperemia, which improved the experimental success rate. The line processing rate reaches 365 kHz, which can be adapted to a high-speed scanning OCTA system.

SignificanceFor over half a century, the three main pillars of conventional cancer therapy are surgery, chemotherapy, and radiotherapy. However, these treatment methods have inherent limitations, as they inevitably cause severe damage to normal cells, particularly immune cells. The discovery and development of immunotherapy show promising clinical applications. Nonetheless, immunotherapy is a double-edged sword, often leading to the occurrence of immune-related adverse events (irAEs) because of off-target effects. Therefore, the current focus in cancer research is to explore treatment strategies that can activate local immune responses while enhancing tumor specificity.Near-infrared photoimmunotherapy (NIR-PIT) is a novel tumor therapy, and it depends on a single antibody-photo absorber conjugate (APC), which combines a monoclonal antibody (McAb) targeted on tumor features with IRDye700DX (IR700). Except for its specific antitumor mechanisms, a unique aspect of NIR-PIT is its direct impact on blood drug delivery. The super-enhanced permeability and retention (SUPR) effects facilitate the rapid leakage of drugs into the tumor, favoring the induction of cytotoxic effects. However, the presence of the “binding site barrier” indicates that using antibodies with low affinity or targeting antibodies with low antigen expression may promote a more even distribution of APCs within the tumor parenchyma. In recent years, researchers have investigated the use of different targeting segments in NIR-PIT, enhancing the tumor immunogenicity, targeting ability, stability, and flexibility of NIR-PIT drugs. This approach has shown considerable potential for application in various types of tumors, with some related clinical trials yielding satisfactory results.Studies have shown a close association between the suppressive tumor microenvironment (TME) and the growth and progression of cancer. In recent years, the targets of APCs in NIR-PIT have expanded to surface proteins of non-tumor cells in TME. The combination therapy of NIR-PIT with immune checkpoint blockade (ICB) has also shown promising experimental results. The development and continuous improvement of optical devices also facilitate the monitoring and evaluation of the therapeutic effects of NIR-PIT. Therefore, it is necessary to summarize previous relevant research to provide a rational reference for the clinical research and application of NIR-PIT.ProgressThe primary mechanism through which NIR-PIT exerts its cytotoxic effects is via a photochemical reaction from IR700. Under near-infrared light, IR700 in APCs undergoes a photocatalytic transformation, changing its chemical properties from hydrophilic to hydrophobic, and aggregating in an aqueous solution. This process leads to the denaturation of the cell membrane antigens bound to it, physical damage to the cell membrane and cell rupture, increased transmembrane water flow, and cell death (Fig.1). Simultaneously, the rapid release of tumor-associated antigens (TAAs) and damage-associated molecular patterns (DAMPs) during NIR-PIT induces immunogenic cell death (ICD), and subsequently, activates the antitumor immune response of the host, enhancing the activation of systemic immune responses to attack other cancer cells and further amplifying the therapeutic effects of NIR-PIT (Fig.2). Current NIR-PIT treatment strategies targeting key components in TME, including immune inhibitory cells (Tregs and MDSCs), cancer-associated fibroblasts (CAFs), and blood vessels, are listed in Table 1. The design principles of APCs and relevant experimental results are also presented. Subsequently, the combined therapeutic strategies and efficacy of immune checkpoint inhibitors with NIR-PIT targeting different cell surface proteins are elucidated. Given the heterogeneity of immune cell populations in different tumors, the choice of ICBs can be based on the expression levels of specific immune checkpoint molecules in their respective tumors.In addition, the progress of clinical trials related to NIR-PIT is summarized, demonstrating that cetuximab-IR700 (RM-1929) can elicit effective antitumor responses in patients with locally recurrent HNSCC where conventional clinical treatments are less effective. Furthermore, the SUPR effect can be quantified using indocyanine green (ICG)-fluorescence and magnetic resonance imaging (MRI) contrast agents to monitor and identify the viability of NIR-PIT. 18F-fluorode-oxyglucose positron emission tomography (18F-FDG-PET), fluorescence lifetime imaging, and bioluminescence imaging can evaluate acute NIR-PIT treatment in preclinical studies. Moreover, the micro distribution of the NIR-PIT agent and its therapeutic effects is monitored using a two-channel fluorescence fiber-imaging system and two-photon microscopy with and without a microprism. The tumoricidal effects and hemodynamic changes induced by NIR-PIT can be monitored by 13C MRI, blood oxygenation level dependent (BOLD) MRI, and photoacoustic imaging.The current investigation of NIR-PIT is relatively limited. In summary, the limitations of replicating IRdye700-McAb conjugates in NIR-PIT, the penetration and uniformity of near-infrared light irradiation, differences in the types and expression of target molecules in different types of tumors, and the safe range of APC dosage in NIR-PIT still require detailed investigations.Conclusions and ProspectsExtensive in vitro and in vivo models study on NIR-PIT have been conducted for various types of tumors, with promising therapeutic outcomes. With its broad and flexible application scope, and various approaches to enhance its efficacy, NIR-PIT has significant potential as a valuable method for cancer treatment.

In recent decades, various techniques have been adopted to improve NIRST system performance, which can facilitate the use of NIRST in breast cancer detection, diagnosis, and treatment. The purpose of this study is to review the current progress on NIRST systems and summarize their advantages and limitations. We also report recent clinical applications of NIRST systems in breast imaging and discuss the challenges and future developments.SignificanceBreast cancer is the most common cancer diagnosed among women worldwide, which accounts for 11.7% of all new cancer diagnoses in 2020. Breast cancer mortality rates decrease significantly when breast tumor is detected early using imaging tools. As an emerging imaging technique, near-infrared spectral tomography (NIRST) has demonstrated potential in breast imaging owing to its nonionizing radiation and high sensitivity and cost-effectiveness. The aim of NIRST is to resolve three-dimensional images of tissue optical properties and chromophore concentrations from acquired multi-wavelength measurements. Therefore, functional information related to biological tissue can be obtained, which is indistinguishable using current clinical breast-imaging modalities. However, NIRST exhibits poor spatial resolution because of light scattering in biological tissues. NIRST system is the key ingredient for producing NIRST images of high spatial resolution.ProgressThis paper presents a review of imaging types (Fig. 2) involved in data acquisition. First, continuous wave (CW) systems, including available commercial instruments, are introduced (Fig. 3). The widely used frequency-domain (FD) and time-domain (TD) systems are summarized (Figs. 4 and 5). The emerging hybrid imaging types and relevant prototype systems are also reviewed (Fig. 6). The integration of conventional breast cancer-imaging systems into NIRST can enhance spatial resolution of NIRST and improve lesion characterization. Therefore, the multimodality imaging systems widely used in breast imaging are also reported (Figs. 7 and 8), particularly in magnetic resonance imaging (MRI)/NIRST interfaces. As incorporating structural information is critical for the accurate clinical diagnosis of breast cancer, the methods including hard prior, soft prior, direct regularization imaging, and the new deep learning methods are discussed (Fig. 9). Their applications in breast cancer diagnosis and prediction response to breast cancer neoadjuvant chemotherapy are also demonstrated (Figs. 10 and 11).Conclusions and ProspectsNear-infrared spectral tomography can provide functional information regarding breast tissue and be used as a supplemental imaging tool for clinical breast cancer-imaging modalities. However, the primary restriction of NIRST is poor spatial resolution. Recent developments in hybrid imaging types and multimodality imaging have facilitated studies on breast cancer management. In addition, deep learning has been applied to NIRST to improve lesion characterization and reduce computational time. The proposed method is expected to assist in breast diagnosis.

SignificanceDigital pathology uses digitized pathological images and their features in conjunction with artificial intelligence technology to achieve quantitative characterization of cancerous tissues and assist pathologists in clinical diagnoses. The use of polarized light illumination and polarized light detection can achieve full polarization imaging. Accordingly, the polarization characteristics of each pixel of the image contain abundant microstructural information, especially subcellular super-resolution information, that is difficult to obtain with nonpolarization imaging. Polarization imaging can provide a more effective means for the identification and quantitative characterization of cancerous tissues. This paper introduces Mueller matrix microscopic imaging techniques and comprehensively reviews the latest methods for polarization feature extraction, including supervised learning-based polarization pixel and image feature extraction, unsupervised learning-based polarization pixel clustering, and the extension of annotations through polarization feature templates based on super-pixels, highlighting their potential clinical applications.ProgressMueller matrix imaging provides abundant subcellular-level information on tissue microstructures. The quantitative extraction of polarization features from Mueller pixels is crucial for the clinical application of polarization imaging. In contrast to stain image-based digital pathology, polarization feature extraction through supervised learning offers more abundant microstructural information. However, the reliance on extensive, well-annotated data poses time and labor challenges. Moreover, supervised learning is dependent on pathologists’ prior knowledge, limiting the comprehensive utilization of information from the polarization space. Unsupervised clustering methods facilitate the decomposition of pathological tissues into distinct microstructural subtypes, enhancing the exploration of the rich information embedded in Mueller pixels. Additionally, this approach provides evidence for the ongoing discovery of new physical properties, structural characteristics, and dynamic processes at all levels above the subcellular scale in organisms, including living entities.Conclusions and ProspectsFollowing advancements in molecular biology techniques, the specific identification of molecular components in biological entities is becoming a pivotal tool in biomedical research, thus leading to diverse omics approaches. Polarization-based digital pathology can leverage feature extraction methods developed in various omics approaches. The unsupervised clustering of Mueller pixels quantitatively extracts information at various levels above the subwavelength scale, enabling the integration of label-free, noninvasive, abundant information features of Mueller matrix imaging into novel spatiotemporal omics methods.

Compared to traditional tumor therapies such as surgery, chemotherapy, and radiotherapy, PDT offers unique and irreplaceable advantages. It is non-resistant, allowing for repeated treatment. PDT exhibits high therapeutic selectivity towards the lesion, causing little to no damage to healthy tissues, and has only a few toxic side effects. Consequently, PDT is especially suitable for elderly and frail patients who are unable to undergo surgical resection or chemotherapy. In particular, for patients with advanced tumors who have not responded effectively to or are at risk with traditional treatments, PDT is an extremely ideal treatment option.Different types of molecules can be used as photosensitizers; however, many of them face challenges in clinical application, including limited penetration depth, low solubility, dark toxicity, and a high dependence on oxygen concentration. Therefore, more efficient and safer photosensitizers need to be further studied and developed. Currently, the focus of research and development of novel photosensitizers lies in target modification and smart nanomedicine delivery systems to achieve minimally invasive and specific therapy. An excellent photosensitizer should be capable of achieving precise lesion killing at low doses while having a minimal effect on other parts of the body. In the context of PDT, the application of novel photosensitizers is undoubtedly a key factor in further improving the therapeutic effect.Progress The earliest photosensitizers used in PDT were hematoporphyrin derivatives, with the main component being dihematoporphyrin ether (DHE). Sodium porphyrinum, marketed by Canadian company QLT (Quadra Logic Technologies Phototherapeutics Inc.), has received approval for the treatment of bladder, esophageal, and lung cancers. It has become the most frequently used photosensitizer in the PDT of non-cutaneous solid tumors. However, it still has certain disadvantages, such as long-lasting skin photosensitivity and low selectivity for lesion tissues. Subsequently, a wider variety of photosensitizers have been developed for treating various diseases (Table 1). There have been many studies on both traditional and novel photosensitizers. Porphyrins, chlorins, phthalocyanines, and bacteriochlorin derivatives have been employed as photosensitizers in clinical use (Table 2). Viscous cycloquinone and metal-ligand anthapurpurin derivatives have entered the clinical research stage as photosensitizers (Table 3). Meanwhile, research focusing on the development of new photosensitizers is also in full swing. Researchers are developing photosensitizers on the nano platform and achieving better drug delivery effects through surface modifications of the photosensitizer. They are also aiming to achieve more accurate PDT through the design of activatable and responsive photosensitizers. Furthermore, they are attempting to overcome the oxygen-depleted microenvironments at tumor sites by developing novel type I photosensitizers and creating photosensitizers more suitable for the treatment of deep solid tumors. Additionally, the combination of PDT with other drugs or therapies, to achieve a better therapeutic effect and reduce drug toxicity and side effects, has also garnered researchers’ interest. Sonodynamic therapy, a derivative of PDT, exhibits higher therapeutic efficiency for deep lesions due to its superior tissue penetration ability. Research on acoustic sensitizer and sonodynamic therapy is also underway.Conclusions and Prospects PDT is playing an increasingly important role in the treatment of many superficial lesions and cancers. The development of photosensitizers with better treatment effects and fewer toxic side effects has been receiving extensive attention. Researchers have made significant efforts in developing more delicately designed photosensitizers. Many photosensitizers with excellent properties, such as high reactive oxygen quantum yield, high molar extinction coefficient, high maximum absorption wavelength, high targeting ability, low in vivo toxicity, and rapid in vivo clearance, have been advanced to clinical research. Simultaneously, more photosensitizers have received marketing approval, benefiting patients. The development of photosensitizers has advanced the diagnosis and precise regulation of diseases, contributing to the development of precision medicine. With the continuous development of novel photosensitizers, PDT will play a greater role in multiple indications and bring benefits to a larger number of patients.SignificancePhotodynamic therapy (PDT) is a novel treatment for superficial skin diseases and tumors. The basic treatment involves administering a photosensitizing agent through intravenous injection or other methods, and then stimulating the lesion with a specific wavelength of light. This photodynamic reaction, facilitated by the photosensitizing agent, effectively cures the lesion. PDT uses the photodynamic effect for diagnosing and treating diseases. Its mechanism is based on a photosensitization reaction accompanied by biological effects that includes the participation of oxygen molecules. This process involves irradiating a laser of a specific wavelength to excite a photosensitizer that has been absorbed by tissues, causing it to enter an excited state. Then the photosensitizer in the excited state transfers energy to the surrounding oxygen, resulting in the generation of highly active singlet oxygen. This singlet oxygen undergoes an oxidative reaction with adjacent biological macromolecules, inducing cytotoxicity, and ultimately, causing cell damage and death. Over the past 20 years, PDT has emerged and developed as a new treatment technology for diseases such as esophageal cancer, lung cancer, condyloma acuminatum, acne, and nevus.

Surface-enhanced Raman scattering (SERS) technology is an ultra-sensitive vibrational spectroscopy technique, which is used to detect plasmonic nanostructures on the surface or near-surface molecules. Due to its fast response, strong specificity, and non-invasive detection characteristics, SERS has been widely used in surface and interface studies, chemical and biosensors, biomedical monitoring, trace analysis, electrochemical reactions, and catalytic reactions. Specifically, in virus detection, it exhibits extremely high detection sensitivity, enabling rapid and accurate detection of minute virus particles. Based on the analysis of virus spectral features, SERS technology can differentiate between different types of viruses, including subtypes and variants. This high specificity leads to a unique advantage in virus tracing, classification, and epidemiological research, which is crucial for the rapid screening of early virus infections and facilitating timely medical intervention. This review systematically summarizes the research progress and potential applications of SERS technology in virus detection over the past two years, considering factors such as the genetic material of the virus, virus types, and the extent of impact (Fig.1).Progress Initially, this study categorizes viruses based on their genetic material, focusing on recent efforts to detect RNA and DNA viruses that threaten human life and health. It offers a comprehensive analysis of both labeled and label-free SERS techniques for detecting these virus types. For RNA viruses, such as SARS-CoV-2, the influenza virus, HIV, and DNA viruses, such as HBV and HPV, label-free detection methods require SERS technology to realize enhanced performance in signal amplification of the detection substrate for direct detection of natural biomolecules without amplification. Notable examples include the trap structure introduced by Yang et al., the nano-flexible substrate by Paria et al., and the semiconductor application by Peng et al., which broaden the application scope of SERS technology. In the realm of SERS signal processing, particularly when combined with machine learning techniques, there is a significant advantage in extracting and analyzing spectral features for identifying potential biomarkers or molecular details in complex and varied samples. The creation of sensitive SERS biological probes in labeling methods is especially critical. Accurately tagging target molecules with Raman signal molecules greatly increases the specificity of the detection platform. For example, Guan et al. employed substrate capture and specific recognition probes for detecting the SARS-CoV-2 antigen, while Su et al. developed SERS labels integrated with CRISPR/Cas technology for the non-amplified detection of target genes. Moreover, the miniaturization and portability of Raman instruments, propelled by technological advancements, are steering SERS toward field applications and real-time analysis, aligning perfectly with the point-of-care testing (POCT) concept. This foundation supports the study’s summary of various initiatives that combine SERS technology with portable Raman instruments. It concludes by offering a summary and outlook on optimization strategies and the current challenges facing the application of SERS technology in virus detection and various POCT settings.Conclusions and Prospects The efficacy of SERS technology in virus detection hinges on several critical factors, such as the design of the enhancement substrate, excitation conditions, the properties of labels and analytes, detection devices, and data analysis techniques. The primary aim is to enhance detection speed and sensitivity while simplifying the detection process for more efficient virus identification. To navigate the intricate challenges posed by viral outbreaks, the development of integrated micro-detection chips capable of identifying multiple viruses, paired with compact Raman detection devices, stands as the ideal approach for future POCT of viruses. Furthermore, investigating the integration of SERS technology with other detection methods—such as chemical separation, biological capture, colorimetry, and advanced computational approaches like machine learning, deep learning, and artificial intelligence—can maximize the benefits of diverse technologies. This integration promises the creation of innovative Raman analysis devices that consolidate sample processing, detection, analytical processing, statistical analysis, result dissemination, and display functionalities, catering to the on-site and real-time testing demands across various sectors. We expect that merging SERS technology with compact Raman instruments will usher in a convenient, efficient, and precise optical POCT method for virus screening, classification, infection tracking, and prognosis forecasting.SignificanceViruses are the primary cause of many infectious diseases, including influenza, high-mortality lower respiratory tract infections, diarrhea, tuberculosis, HIV infection, dengue fever, hepatitis B, and more. These diseases can cause severe damage to various systems in the human body and can even lead to life-threatening conditions. The outbreak of infectious viruses poses a significant challenge to public healthcare systems. Early and accurate virus diagnosis is crucial in preventing virus spread, especially in the absence of specific vaccines or effective medications. Existing traditional detection methods often require complex equipment and the expertise of skilled operator. Hence, it becomes challenging to conduct large-scale testing in rapidly spreading virus-infected areas.

SignificanceSkin diseases are common human conditions, and their detection and diagnosis are necessary. Because of the influence of doctors' subjectivity and skin trauma, traditional detection methods are inadequate for accurate and effective diagnosis of skin diseases. Therefore, skin imaging techniques are gradually being used for diagnosis. The photoacoustic imaging technique is an emerging imaging method that combines the high contrast of optical imaging with the deep imaging advantages of ultrasound imaging. Photoacoustic images provide structural and functional information to assist doctors in diagnosing diseases and to improve the accuracy of assessment and treatment. Photoacoustic skin imaging technology can satisfy imaging requirements of different hardware configurations, and its variety of hardware forms ensures that the technology can achieve microscopic and macroscopic imaging, with the potential to respond to diverse clinical needs. By using this technology, melanin and hemoglobin can be detected when capturing images of melanin particles and microvessels at different depths in the palm of the human hand, which can be used for diagnosing pigmented and vascular skin diseases. Photoacoustic skin imaging provides high-resolution images of all skin layers, which is crucial for the early diagnosis and evaluation of skin diseases. Therefore, this paper reviews the systematic classification of existing photoacoustic skin imaging modalities and the performance enhancement methods of image reconstruction algorithms, describes several applications of photoacoustic imaging in clinical human research, and analyzes the advantages and clinical potential of photoacoustic skin imaging as an emerging imaging technology. Thus, readers can gain a detailed and comprehensive understanding of photoacoustic skin imaging technology.ProgressThis paper reviews and summarizes the photoacoustic skin imaging technology. First, photoacoustic skin systems are classified based on the imaging modality. Existing photoacoustic skin imaging systems are divided into photoacoustic microscopic and other photoacoustic skin imaging systems. The latter includes photoacoustic tomography and ultrasound/photoacoustic multimodal-imaging systems. This article summarizes research with superior performance in terms of imaging principles, resolution, imaging depth, scanning modes, and other hardware specifications. The corresponding system components are outlined. Subsequently, the research progress in photoacoustic microscopic skin imaging systems and other photoacoustic skin imaging systems is summarized in terms of comparison of the overall system performance.In studies on photoacoustic microscopy imaging systems, significant progress has been achieved in improving photoacoustic dermoscopy systems, in-vivo skin microimaging, and multiscale skin microimaging, resulting in advancements in system performance (Table 1). Moreover, for other types of photoacoustic skin imaging systems, studies have focused on various aspects, such as photoacoustic tomography of subcutaneous blood vessels in the extremities, three-dimensional photoacoustic tomography, diode laser-based skin tomography systems, and ultrasound/photoacoustic multimodal imaging systems. These investigations lead to noteworthy research outcomes and enhancements in the hardware performance of skin imaging systems (Table 2). In addition, the inclusion of commercial skin imaging systems in the listings validates the practical application value of photoacoustic skin imaging systems.This paper summarizes existing methods and strategies for enhancing the performance of photoacoustic imaging systems, with a focus on advancements in reconstruction algorithms. The analysis categorizes and discusses these methods based on three main aspects: imaging resolution enhancement algorithms, imaging depth enhancement algorithms, and noise removal algorithms. Each category is analyzed chronologically, starting with an overview of conventional and pivotal performance enhancement algorithms. Subsequently, the discussion encompasses performance enhancement algorithms that integrate deep-learning techniques. Finally, existing specialized algorithms are discussed.This paper summarizes research on the clinical application of photoacoustic skin imaging technology, classifies skin diseases into two categories (skin cancer and other skin diseases), and summarizes the photoacoustic skin imaging methods for detecting typical diseases. On the one hand, the research teams are currently focusing on detecting melanin and collagen content in the detection and investigation of skin cancer. On the other hand, the imaging of blood vessel shape and distribution pattern can be used as a criterion to determine whether the detected area is diseased and to identify the lesion boundary. In this paper, other skin diseases are classified as inflammatory, vascular, or pigmented according to their causative factors. The pathological features of the diseases and detection methods based on photoacoustic skin imaging technology are described using typical diseases as examples. A summary of the clinical applications of this technology for diverse skin diseases demonstrates its unique advantages and potential for clinical applications.The concluding section of this article highlights the prevailing challenges of photoacoustic skin imaging and outlines the corresponding research directions aimed at addressing these issues. These challenges include resolving the issue of dynamic changes in clinical data, advancing multimodal imaging capabilities, developing user-friendly imaging devices, and establishing standardized imaging protocols and data analysis techniques.Conclusions and ProspectsPhotoacoustic skin imaging is an emerging technique with several advantages, such as excellent imaging quality, cost-effectiveness, tissue safety, and promising clinical potential. Photoacoustic imaging is anticipated to become widely used in the future for clinical skin examinations. Further exploration and development of photoacoustic skin imaging technology are required to advance its clinical applications and facilitate its integration into medical practice.

The complexity of tumor biology is a multifaceted challenge that is governed by the intricate relationship among genetic mutations, epigenetic alterations, and the tumor microenvironment. Tumors are not static—they evolve through a series of genetic and epigenetic changes that enables them to evade the host’s immune system and resist the effects of various treatments. The tumor microenvironment, which comprises a diverse array of cell types, extracellular matrix components, and signaling molecules, significantly affect tumor growth, metastasis, and response to therapy. This renders it difficult to develop comprehensive treatment plans that can effectively target the specific characteristics of each tumor.Optical microscopy imaging technologies have been adopted widely in precision oncology as they can address the challenges posed by the complexity of tumor biology. These technologies allow one to visualize and analyze tumor tissues and cells with high resolution, thus enabling quantitative and spatially localized analysis of genomic, proteomic, and metabolomic information. This level of detail is critical for identifying patient-specific molecular characteristics and biochemical abnormalities for developing targeted treatment strategies.The significance of optical microscopy imaging in precision oncology is manifold. First, it bridges the difference between the genomic and phenotypic aspects of cancer, thus allowing for a more nuanced understanding of tumor behavior and response to therapy. Second, it enables the identification of biomarkers that can predict treatment response, thus providing guidance in selecting the most appropriate treatments for individual patients. Third, the non-invasive nature of these imaging techniques allows for the repeated monitoring of tumor progression and response to treatment, thereby facilitating real-time adjustments to treatment strategies as necessary.The potential of optical microscopy imaging to transform cancer treatment is substantial. By providing detailed, patient-specific information, these imaging techniques can facilitate the development of more effective and less-toxic treatment regimens. This personalized approach can improve patient outcomes by increasing the efficacy of therapies and reducing the incidence of adverse effects. Furthermore, the ability to monitor treatment response in real time can facilitate more informed clinical decision-making, thus potentially improving the overall survival rates and quality of life of patients with cancer.In conclusion, the integration of optical microscopy imaging into precision oncology is a significant advancement in cancer treatment. Optical microscopy imaging technologies are effective for understanding the complex biology of tumors and for guiding the development of personalized treatment strategies. As research in this field continues to progress, the potential for optical microscopy imaging to revolutionize cancer diagnosis and treatment will be immense, thus affording more targeted therapies and better patient outcomes in the future. The continued evolution of these technologies is crucial for bridging the disparity between genomic research and clinical practice, thus ultimately resulting in more effective and personalized cancer treatments.Progress Optical microscopy imaging techniques have progressed significantly in the field of precision oncology and can provide a comprehensive view of tumor characteristics. Auto-fluorescence (AF) imaging has been utilized to monitor metabolic activities within tumors and offers label-free insights into drug responses and cellular metabolism (Fig.5). Second harmonic generation (SHG) imaging has been pivotal for analyzing the extracellular matrix (ECM), particularly collagen fiber organization, which is crucial for understanding tumor invasion and metastasis (Fig.7). Coherent Raman scattering (CRS), in particular stimulated Raman scattering (SRS), has emerged as an effective tool for imaging tumor metabolites without requiring labels. SRS has been instrumental in revealing metabolic heterogeneity, which is vital for identifying therapeutic targets and understanding cancer-cell metabolism (Fig.8). Mid-infrared photothermal (MIP) imaging has demonstrated its potential in assessing drug pharmacokinetics and pharmacodynamics by imaging the distribution of drugs within cells and tissues at a deep cellular level (Fig.9). Furthermore, multiplex immunofluorescence (mIF) and fluorescence insitu hybridization (FISH) have been employed for immunophenotyping (Fig.4) and genetic analysis (Fig.6), respectively, to characterize the immune microenvironment and detect gene amplifications. These techniques, as summarized in Table 1, collectively contribute to the increasing number of tools available for the characterization of tumors and the optimization of targeted therapies, thus ultimately improving patient outcomes in cancer treatment.Conclusions and Prospects Optical microscopy imaging is becoming essential in precision oncology as it allows one to understand the relationship between tumor genetics and phenotypes. As the field progresses, the integration of these imaging techniques into clinical settings will become more evident, which will significantly improve cancer diagnostics and treatment. Future studies shall be conducted to render this technology more accessible by reducing equipment costs and enhancing imaging methodologies, thereby solidifying its key role in precision oncology.SignificancePrecision oncology is imperative for accommodating the distinct journey of each cancer patient, which is determined by the unique genetic, molecular, and cellular profiles of individual tumors. This shift from a general treatment model to a personalized approach is driven by the recognition that each patient with cancer presents a distinct set of challenges that must be addressed to achieve optimal therapeutic outcomes and prognostic accuracy. The conventional methods of cancer treatment, which typically involve generalized therapies, are deficient owing to the heterogeneity of tumors and the dynamic nature of cancer progression.

SignificanceSince 2020, breast cancer has emerged as the most prevalent cancer globally and a leading cause of cancer-related deaths among women. Affected by various genetic or environmental carcinogenic factors, breast cells undergo irreversible gene mutations, initiating the uncontrolled proliferation of malignant cells that crowd into clusters to form breast tumors. The in-situ tumors induce local tissue hypoxia in their internal and surrounding areas, leading to vascular hyperplasia, which propels the growth of cancer cells and their invasion into normal tissues.Medical imaging is the primary tool for breast cancer screening, diagnosis, and treatment assessment. Early screening plays important roles in reducing mortality; accurate diagnosis is essential for effective treatment; and treatment assessment is critical to provide timely feedback and prognosis of cancer responses. Conventional imaging methods for breast cancer, such as mammography, ultrasonography, and magnetic resonance imaging, though widely used in clinics, exhibit limitations including low diagnostic specificity, slow imaging speed, ionizing radiation, or the need of contrast agent injection. For instance, more than 75% of patients receive benign biopsy results after ultrasound diagnosis. Furthermore, current imaging modalities lack the capacity to provide real-time monitoring, evaluation, and prognosis of the cancer responses during neoadjuvant therapy. New imaging modalities with complementary advantages are crucial to address the evolving clinical demands.Photoacoustic imaging (PAI) is an emerging technology in the biomedical imaging field and has garnered significant attention owing to its exceptional performance. In addition to its high imaging speed, high spatiotemporal resolution, ionizing-free radiation, and abundant penetration, PAI can provide rich functional optical contrast to reveal physiological characteristics of the tumor microenvironment underneath the skin.ProgressMultiple research groups in the PAI field have achieved notable technical breakthroughs for breast cancer screening, diagnosis, and treatment assessment. Regarding early screening, advanced PAI devices have been developed based on customized ultrasonic arrays. These devices aim to detect physiological characteristics such as vascular proliferation, increased hemoglobin concentration, and abnormal blood oxygen saturation in breast tumor areas through entire breast scanning. Some teams have explored the integration of PAI and ultrasonography, utilizing the complementary anatomical information. As concerns breast tumor diagnosis, numerous clinical studies have demonstrated that physiological characteristics in the microenvironment of a tumor can improve the distinction between benign and malignant breast tumors, facilitating accurate BI-RADS classification and reducing the chance of benign biopsy. The high imaging contrast of PAI also enables the guidance of breast sentinel lymph node biopsy with better clearance. While the combination of PAI with exogenous contrast agents and molecular probes is still in the preclinical stage, it holds the potential for more specific diagnosis in future. Regarding treatment assessment, PAI proves efficient and safe in recording physiological dynamics of the cancer microenvironment in response to therapy, offering crucial prognostic information and seamless feedback to the treatment. In addition, the label-free nature of ultraviolet PAI also provides H&E-like images without the need for staining, exhibiting early promise for accurate and rapid detection of tumor margins intraoperatively.Conclusions and ProspectsRegardless of the numerous advantages and multiple niche applications, PAI still faces several challenges to achieve wide clinical usage. First, the spread of PAI technologies depends on the established standards of system design, operation, and data processing to reduce the significant performance disparities among devices developed by different teams. Second, several feasibility studies have been conducted in the PAI field but large-scale clinical studies are still lacking. The PAI indicators revealed from breast cancer images have not been systematically documented or incorporated into clinical practice. Third, a gap still exists between the technical teams and clinical needs. For instance, while three-dimensional PAI exhibits better image clarity for lesion measurement, clinical practices and diagnostic analyses still heavily rely on real-time two-dimensional sectional imaging. Accordingly, to further establish its clinical value, PAI researchers need to evolve from scattered and small-scale feasibility studies to large-scale clinical trials addressing fundamental medical questions. This involves improving existing diagnostic and treatment methods and ultimately integrating them into the existing clinical framework.

Progress We introduced a series of research efforts to advance the intraoperative application of optical coherence imaging. Vascular characteristics are an important basis for intraoperative pathological assessment. We first introduced OCT angiography with adaptive multi-time intervals, which proposes a time-efficient scanning protocol by adaptive optimization of the weights of different time-interval B-scan angiograms. This novel OCTA technique achieved better performance, with a visible vascular density increase of approximately 67% and a signal-to-noise ratio enhancement of approximately 11.6% (Figs. 2 and 3). In the context of intraoperative applications, we introduced robot-assisted OCTA, which integrated a high-resolution OCT system with a 6-degree of freedom robotic arm (Fig. 4). Robot-assisted OCTA can achieve wide-field imaging of artificially determined scanning paths. High-resolution vascular imaging of the mouse brain by robot-assisted OCTA successfully confirmed the effect of unevenly distributed resolution and fall-off caused by the large-curvature sample (Fig. 5). Thereafter, we introduced a microscope-integrated OCT system that can be well integrated with current intraoperative equipment and does not need to pause the surgical process (Figs. 6 and 7). Providing real-time tissue depth information to a doctor can help improve their decision-making ability in delicate surgical procedures such as ophthalmology and nervous system surgery. Intraoperative three-dimensional (3D) real-time imaging requires an OCT system with high imaging and processing speeds. Thereafter, we introduced the 10.3 MHz ultra-high speed scanning laser with stretch pulse mode-locked based on polarization isolation (Fig. 8), which employs a simple and low-cost approach to suppress the transmitted light and achieves an effective duty cycle of ～100% with only one CFBG and no need for intra-cavity semiconductor optical amplifier (SOA) modulation, extra-cavity optical buffering, and post amplification (Fig. 9). Real-time 3D OCT imaging is necessary for practical intraoperative applications, and a series of studies have been conducted to achieve this goal. A home-built 3.28 MHz FDML based OCT system combined with GPUs (NVIDIA, GeForce GTX690, and GeForce GTX680, USA) achieved real-time processing and visualization of 3D OCT data (Fig. 10). The imaging range and longitudinal resolution can be flexibly adjusted by changing the spectral range of the output.Although OCT offers high-quality structural and vascular imaging, it lacks cellular resolution, which limits detailed tumor analysis. Dynamic full-field OCT (D-FFOCT) is an optically active rapid pathological imaging technology based on array interference detection that captures subcellular metabolic motion at millisecond temporal and nanometer spatial scales, and significantly enhances tumor diagnostics by providing detailed insights beyond conventional OCT capabilities (Fig. 11). Normal and diseased tissues can be accurately distinguished by analyzing the temporal characteristics of dynamic signals, such as amplitude, frequency, and standard difference. Through the use of high-power objective lenses and broadband light sources, the resolution can reach sub-microns, and as an imaging tool for intraoperative tissue sections, it is fast, easy (no freezing or staining is required), and highly accurate. Freshly isolated mouse brain glioma sections were imaged using the D-FFOCT system, which showed a clear boundary, distinct cell structure, and dynamic intensity between the glioma and normal brain tissue (Fig. 12).Conclusions and Prospects Advancements in OCT technology, including the significantly increased sweep speed of the light source, improvement of the probe for the intraoperative scene, optimization of the blood flow algorithm, and high-speed data processing capability supported by the GPU, make real-time intraoperative 3D tomography possible. D-FFOCT imaging with a cell-resolving ability is an important step forward in the timely pathology of tumor resection. The integration of advanced OCT technologies into clinical practice heralds a new era of precision medicine in which surgical accuracy is significantly enhanced and tumor recurrence is minimized. Future studies should focus on further refining OCT capabilities, integrating these advanced technologies to improve clinical practicability, expanding their applications across different types of cancer, and integrating AI to automate and enhance diagnostic accuracy. This vision foresees OCT not only as a tool for improved surgical interventions but also as a pivotal element in the broader strategy of personalized and targeted treatment approaches, offering a beacon of hope for more effective cancer management and patient recovery paths. The ultimate goal is to establish OCT as an indispensable tool for tumor surgery and management, revolutionizing patient care and outcomes.SignificanceOptical coherence tomography (OCT) plays a pivotal role in medical imaging, particularly in enhancing the tumor resection accuracy. The significance of this technology lies in its ability to improve patient prognosis by providing real-time, detailed visualization of tumor boundaries and invasiveness, thereby reducing recurrence rates and aiding the precise removal of malignant tissues.

SignificanceMagnetic field quantum sensors, including superconducting quantum interferometers, laser-pumped atomic sensors (LPAS), and nitrogen-vacancy centers in diamonds, utilize quantum systems or effects to precisely measure magnetic fields. Laser-pumped atomic magnetometers, known for their high sensitivity, compact size, low power consumption, and ease of maintenance, represent a rapidly evolving research area. LPAS are applied in nuclear magnetic resonance (NMR) for obtaining more accurate magnetic resonance spectra of materials and for measuring samples under unique conditions. This expands the detection and analytical capabilities in discerning the fine structure of biological and chemical substances. They are anticipated to serve as an effective complement to high-field NMR techniques.ProgressNMR based on LPAS has been developed rapidly in recent years. Researchers have integrated hyperpolarization technology, sample transmission, and coding technology with high sensitivity and broad bandwidth LPAS. This integration enables the performance of zero- to ultralow-field NMR on various chemical samples. It allows for the acquisition of the samples’ zero- to ultralow-field NMR spectra and facilitates the theoretical analysis of these spectra. Additionally, the researchers have successfully conducted zero- to ultralow-field NMR measurements of chemical reactions within metal sample tubes. This advancement permits non-destructive, real-time monitoring of the polarizability of hyperpolarized samples. Furthermore, combining this with image coding in NMR, zero- to ultralow-field magnetic resonance imaging (MRI) of the human brain and hand has been realized.Conclusions and ProspectsLPAS method and technique are crucial for realizing zero- to ultralow-field NMR and MRI. LPAS offers low manufacturing costs, simple maintenance, easy miniaturization, and boasts an ultra-narrow linewidth with high sensitivity of approximately fT/Hz1/2. Utilizing LPAS technology has transformed zero- to ultralow-field NMR into a powerful tool, especially in fields such as biochemistry. Building on this, the integration of nuclear spin polarization enhancement technologies and sample transport technologies addresses the challenges of performing NMR and MRI in the thermal polarization measurement environment of the sample at zero- to ultralow fields. This integration effectively broadens the application scope of LPAS-based NMR and MRI methods and technologies. By combining these with zero- to ultralow-field NMR coding techniques, high spectral and imaging resolutions are achievable. Additionally, there are fewer restrictions on the materials of the substances being detected, offering innovative directions for the development of NMR measurement and MRI methods in biomedicine and chemical materials.The development of nuclear magnetic resonance spectrometers based on LPAS has progressed rapidly. However, there are still areas for improvement, such as enhancing the analysis of zero- to ultralow-field NMR spectra, improving the measurement resolution of zero- to ultralow-field NMR spectrometers, and achieving further miniaturization of these spectrometers. Zero- to ultralow-field NMR spectroscopy necessitates the integration of the physical and chemical information of the sample being tested and detailed analysis using controlled coded pulses. The resolution of the spectrometer can be enhanced through the application of hyperpolarization technology and by increasing the sensitivity of LPAS. Miniaturization is a key development trend for zero- to ultralow-field NMR spectrometers. The current size of LPAS has been reduced to centimeter scale, and with advancements in new materials and manufacturing technologies, there is potential for even further miniaturization.

SignificanceOptics, which is a significant sub-discipline of physics, focuses on the study of the phenomena, properties, and applications of light. Optics has evolved into an independent discipline over time. Optical imaging plays a crucial role in optical research by utilizing the phenomena and properties of light to record images of objects. Optical imaging has extensive applications in diverse fields, including astronomy, medicine, communication, and photography. For example, with the ongoing advancements in biomedical research, optical imaging has progressively showcased its distinctive advantages. First, optical imaging offers high resolution that is free from ionizing radiation, making it safer than X-rays or gamma rays that pose the potential risk of cancer. In addition, optical imaging can be flexibly configured to provide rich biomedical information based on the amplitude, phase, wavelength, polarization, and other characteristics of light. Another advantage of optics is their exceptional sensitivity, which enables the precise and sensitive detection of interactions between light and tissue components or molecules. Finally, the application of contrast agents further enhances the imaging specificity and contrast, thereby improving the visualization of desired targets and opening new avenues for disease diagnosis and treatment.These have spurred the development of a vast range of high-resolution optical imaging technologies, such as confocal microscope, multiphoton microscope, and super-resolution imaging, which have been achieved by exciting fluorescence signals and/or utilizing gating or nonlinear optical effects in tissue samples. However, these implementations without exception have encountered fundamental challenges in thick biological tissues. This limitation stems from the strong scattering of light in tissue due to the inherent inhomogeneous spatial distribution of the refractive index of the medium encompassing diverse tissue constituents and functions. As a result, when light propagates within biological tissues, the light beam spreads quickly and is accompanied by the accumulated scattering of light (approximately one scattering event per 0.1-mm optical path length at visible wavelengths), which also rapidly weakens the intensity of non-scattered light in situ. In combination, these result in an intrinsic trade-off between spatial resolution and penetration depth for optics in biological tissues. This is also why optical techniques that utilize ballistic or quasi-ballistic photons typically have an effective penetration depth of less than or approximately 1 mm beneath the skin, which corresponds to 10 times the transport mean free path in the visible and near-infrared regimes. Excessive laser power may further enhance tissue penetration depths, but it also poses a risk of damaging biological tissues, particularly the skin and subsurface.In the past two decades, numerous studies have been conducted to address these challenges, including switching to longer wavelengths to obtain lower tissue scattering coefficients, converting diffused light into non-scattered ultrasound at the signal detection side, and creating a minimally invasive optical path via ultrathin fibers to deep tissue regions. We believe that summarizing these advancements is not only worthwhile, but also critical for inspiring further research aimed at greater penetration depths and faster speeds toward wider applications.ProgressIn this review, we summarize the recent efforts in deep-tissue optics from various perspectives based on the mechanism of operation, including physical, computational, learning, and fiber optics. Note that this is not a complete list but only an empirical one.Regarding physical-optics-based efforts, relevant research has primarily focused on the three aspects of wavelength engineering, energy conversion, and phase compensation. Wavelength engineering, such as multiphoton imaging and up-conversion imaging, involves the transformation of the input light wavelength into a different output wavelength to enhance the penetration depth. In multiphoton fluorescence imaging, two or more photons with longer wavelengths but lower energies are absorbed almost simultaneously before exciting the target fluorescent molecules at depth, generating one photon with shorter wavelength but higher energy. The longer wavelength in excitation and elevated photon energy in emission both contribute positively to the increased penetration depth for imaging. Up-conversion imaging entails the sequential absorption of multiple low-energy photons and their conversion into a single high-energy photon, thereby increasing the penetration depth.Among approaches based on energy conversion, the photoacoustic (PA) effect, which converts input pulsed light into ultrasonic waves, has been extensively studied. When a biological tissue absorbs light energy, it undergoes thermal transformation, leading to localized expansion in the region of interest. Conversely, when the optical illumination is switched off, the local temperature decreases, causing the tissue region to contract. When the activation and deactivation of optical illumination (such as pulsed light) are manipulated, the expansion and contraction of tissues can be controlled, generating periodic mechanical waves in the ultrasonic frequency (MHz) range. These are usually referred to as photoacoustic or optoacoustic signals and are detected by one or an array of ultrasound transducers positioned outside the tissue sample. Because the generation of PA signals relies on the optical absorption of light, optical absorption contrast is obtained in PA imaging. However, the generation of signals does not distinguish between ballistic or diffused photons, and the detection of signals is based on ultrasound, which scatters much less (~1/1000) than light in the tissue. In combination, these features lead to a considerably boosted balance between imaging resolution and penetration depth and enable many exciting applications that are not possible with pure optical technologies.In phase compensation, optical devices are utilized to measure and compensate for the optical phase distortion induced by light scattering. One representative example of phase compensation is optical phase conjugation, which captures the phase distortion of the wavefront emitted by a guide star within the scattering medium and compensates for it by conjugately adjusting the incident wavefronts and then refocusing light onto the position of the guide star. The phase-conjugation mirror, which is typically a photorefractive material, is responsible for recording the incident wavefront pattern and generating conjugated light that propagates along the optical path opposite the original transmission path.Computational optics is an interdisciplinary field that merges optics and computers to leverage physics and algorithms, thereby enabling applications beyond those that can be achieved using traditional optical systems. The primary computational optics-based efforts in deep-tissue optics include digital optical phase conjugation (DOPC), iterative wavefront shaping, and transmission and reflection matrices. In DOPC, the phase-conjugation mirror previously discussed is replaced by the integration of a digital camera, computer, spatial light modulator, and algorithms for determining and generating the phase-conjugated wavefront. In iterative wavefront shaping, the phase of the incident light wavefront is adjusted based on feedback signals and the focusing performance is iteratively optimized. Feedback signals can take various forms, such as focal intensity, peak-to-background ratio (PBR) in the captured pattern, and photoacoustic signal strength. In the transmission matrix, a linear mathematical model is used to describe the relationship between the incident and scattered output wavefronts to characterize the scattering medium. If we denote the input wavefront as ein and the output wavefront as eout, the transmission matrix (MTM) can be characterized as eout=MTM⋅ein. By measuring the transmission matrix, we can focus the diffused light, project specific patterns through a scattering medium, or retrieve images from speckles. The reflection matrix establishes the relationship between the incident and reflected wavefronts from a scattering medium. In deep tissues, it is typically impractical to define or position guidestars or obtain guidestar signals within or on the opposite side of a tissue sample. Thus, applications of transmission matrices are limited. The introduction of a reflection matrix addresses this challenge by utilizing a reflected wavefront instead of a transmitted wavefront. In this scenario, both the incident and reflected light detectors are present on the same side of the scattering medium, thereby circumventing the need for guidestars to be placed on the opposite side of the scattering medium.These computational optics-based efforts typically rely on intricate physical models to achieve the focusing or imaging of simple targets, such as letters, numbers, and other basic patterns, through scattering media. With recent advances in artificial intelligence, complicated problems involving speckles can now be addressed using deep learning. For example, deep-learning-based speckle imaging has powerful learning capabilities and data-driven characteristics. Deep neural networks can be trained using known data pairs, including ground-truth images and corresponding speckles, to extract various dimensions of information features. This can enable the high-fidelity reconstruction of target images, such as human face images. In addition, by training the speckle patterns obtained under different states of perturbed scattering media, the generalization capabilities of deep neural networks can be further improved, and the robustness of handling perturbed scattering media exceeds that of transmission-matrix-based methods.In addition to these endeavors, which are all aimed at noninvasive deep-tissue optics, minimally invasive solutions that employ ultrathin optical multimode fibers as light guides into the tissue are also attractive and have seen promising advancements in recent years. Multimode fiber-based imaging is advantageous due to its minimally invasive nature, flexibility, and affordability. However, because of mode dispersion and coupling within multimode fibers, the optical field output from the fiber appears to be similar to a speckle pattern from tissue-like scattering media, making it infeasible to directly interpret the transmitted spatial information. Nevertheless, if multimode fibers are treated as scattering media, the aforementioned wavefront shaping approaches can be applied to multimode fibers. Thus, with the integration of wavefront shaping, the speckled output from a lensless multimode fiber can be focused onto a single optical mode, and then the raster can scan at a high speed within the field of view of the fiber. The excited or responding signals can also be detected and relayed using the same fiber for further use. This creates a scenario very similar to laser confocal microscope, except that the probe is inserted deep into the tissue. As a result, spatially and/or temporally resolving optical signals from deep tissues can be excited and detected with high resolution, which opens avenues for exciting new optical practices that require high resolution at depths in tissue. This capability can also be extended beyond imaging, such as for optogenetics, where wavefront shaping-empowered multimode fibers can deliver light precisely to targeted neurons within deep tissues and pick up fluorescence signals reflecting neuronal activities, enabling precise activation or inhibition of neurons to study brain functions.Conclusions and ProspectsOptics have gained significant attention in the study of deep biological tissues due to their non-ionizing radiation, exceptional contrast, exquisite specificity, and heightened sensitivity. In addition, the integration of computational optics and deep learning with conventional optics has substantially enhanced penetration depths while preserving moderate resolution in deep biological tissues. Despite these remarkable advancements, the practical implementation of deep-tissue optics still encounters critical challenges that must be addressed before moving forward.The first is the penetration depth. With photoacoustic efforts and wavefront shaping techniques, which are sometimes further aided by computational optics and deep learning, current practices have achieved high-resolution optical focusing and/or imaging far beyond the optical diffraction limit. While most experimental research efforts to date still concentrate on small animal models such as mice, future studies are anticipated to improve the depth capability and extend to large animal models such as rabbits and monkeys. This transition is necessary for assessing the practicality, safety, and reliability of clinical diagnostics and therapeutic applications before working with human patients.Speed is another crucial factor in the operation of deep-tissue optics. To reverse or compensate for the scattering-induced wavefront distortion, the scattering medium or multimode fiber should theoretically remain stationary to maintain the medium status, equivalent to the transmission matrix, during the wavefront optimization process. However, in practical applications, this requirement is hardly met, particularly for living biological tissues, whose optical field decorrelates rapidly on the order of milliseconds or even faster due to factors such as blood flow and respiration. Although some operations based on physical optics, such as optical phase conjugation, can reach this time scale, the majority of wavefront shaping implementations to date, consume seconds or hundreds of milliseconds, which is mainly limited by the response rate of the hardware such as spatial light modulators.Over the past few years, deep learning has significantly affected deep-tissue optics. By leveraging the power of deep neural network models, it excels in extracting features and establishing nonlinear relationships between the target information (the ground truth) and the corresponding speckles, enabling high-fidelity retrieval of the original information from speckles. In addition, the use of deep learning has expanded the scope of speckle imaging, enabling breakthroughs in scattering, virtual staining, optical encryption, optogenetic networks, etc. The integration of deep learning with deep-tissue optics is expected to improve the speed, penetration depth, and immunity to system and medium disturbances. In addition, the combination of deep learning with physics-based scattering models holds great potential for accurately understanding and modeling multiple scattering processes, which is essential for designing efficient computation algorithms.Finally, noninvasive deep-tissue optics in vivo still remains limited in some respects and may require a few more years to achieve technical maturity. Accordingly, a temporary yet effective alternative is to integrate wavefront shaping with ultrathin multimode fibers. Because the diameter of the multimode fiber can be 100‒200 μm, close to the typical hair diameter of adults, this integration can create a minimally invasive optical path into deep biological tissue, enabling high-resolution and fast-scanned optical focusing, imaging, stimulation, and manipulation at depths in tissue. Although it is not a perfect solution, it is practically useful in many studies, particularly for those at the early and preclinical stages, or when the insertion of a fiber-based probe is accompanied by invasive surgery, and the insertion of the probe does not considerably increase the degree of invasion or discomfort to the patient.The developments to date in this field have demonstrated the feasibility and potential of deep-tissue optics. With continuing efforts and progress in related areas, technical barriers, such as the speed bottleneck associated with the response rate of spatial light modulators and the insufficient generalization capability of neural networks, can be overcome. It is strongly envisioned that in the near future, deep-tissue optics will reach practical maturity and be usable in vivo, which can extend many exciting optical applications to tissue regions that are currently optically inaccessible. This could reshape the landscape of light use in biomedicine and many other areas.

SignificanceOwing to its non-invasiveness and high specificity, fluorescence microscopy is widely utilized in biomedical research to investigate the structures and functions of biological systems. Limited by the diffraction of light, the resolution of conventional fluorescence microscopy is ~250 nanometer (nm) and ~800 nm on the lateral and axial axes, respectively, and it cannot resolve nanostructures beyond this limit. To overcome the resolution limit, many super-resolution fluorescence microscopy techniques have been developed, enabling biologists to record the dynamics of the fine structures of organisms and cells in their active states. This offers the potential to elucidate the crucial details of biological phenomena.Nevertheless, in super-resolution fluorescence microscopy, trade-offs exist between resolution, speed, and imaging depth. Although these trade-offs can be moderated by optimizing the microscopy hardware, certain strict physical limitations cannot be easily overcome. Therefore, enhancing microscopy performance via computational imaging methods is particularly important. For instance, the application of deconvolution algorithms can transcend physical limits without changing the optical hardware, thereby improving the dissection of biological information.ProgressThis review introduces the technical principles of various deconvolution methods. Deconvolution techniques are applied to four modes of super-resolution fluorescence microscopy: structured illumination microscopy (SIM), image scanning microscopy (ISM), stimulated emission depletion (STED) microscopy, and super-resolution optical fluctuation imaging (SOFI). Various modalities have been used for live cell imaging applications. For example, researchers have designed deconvolution algorithms to eliminate the reconstruction artifacts produced during the reconstruction of SIM and to improve its resolution. Additionally, for SOFI, deconvolution techniques can be applied as pre- or post-processing steps to further enhance the efficiency of utilizing statistical information and to improve resolution. The recently developed advanced deconvolution algorithm, sparse deconvolution, is stable and robust to various noise conditions and can effectively improve the three-dimensional resolution two-fold. Furthermore, it can be combined with different variants of fluorescence microscopy to enhance their contrast and resolution in situ without any changes. Owing to significant advances in the corresponding super-resolution reconstruction techniques, live-cell super-resolution microscopy has been effectively enhanced.In the outlook section, considering the unrolling algorithm as an example, this review discusses the prospects of deconvolution methods based on deep learning. The combination of deep learning algorithms and microscopy imaging techniques may become a future development trend in the field of live-cell super-resolution microscopy. This review briefly describes the Fourier ring correlation (FRC) image resolution measurement method and its application in image reconstruction. Finally, a rolling FRC (rFRC) method is introduced to quantitatively detect the reconstruction uncertainties of super-resolution techniques at the corresponding super-resolution scale.Conclusions and ProspectsOwing to hardware limitations, extensive super-resolution microscopy methods have introduced computational steps to achieve the optimal quality of super-resolution imaging. This review can serve as a bridge between the super-resolution microscopy and computation communities to facilitate the application of novel computational techniques toward improved resolution, accuracy, and image processing.

SignificanceThe neurovascular unit (NVU), a critical component of the brain, regulates almost all physiological process. The precision of the morphology and function presentation regarding the NVU provides hope for advancing research on basic neuroscience, as well as diagnosing brain diseases, which are common desires of the “Brain Project” worldwide. Accordingly, high temporal and spatial resolution visualization techniques are required. Fluorescence microscopic imaging technology has significant advantages in terms of specificity, diversity, image contrast, and spatio-temporal resolution; however, due to the limited penetration depth of light in tissue, use of noninvasive fluorescence imaging to obtain high-resolution structural and functional information of NVU is difficult in deep brain regions in vivo. As a result, fluorescence endoscopic microscopy imaging technologies based on micro probes are becoming more popular among brain science researchers.ProgressOver the last two decades, a series of neurobehavioral studies in vivo have been conducted using fluorescence endoscopic microscopy. With endoscopic probes implanted into the brain, the NVU in most deep regions can be observed clearly in living mice, including the hippocampus, dorsal striatum, amygdaloid nucleus, and epithalamus. Incorporating an upright microscope or a head-mounted mini microscope, gradient refractive index (GRIN) lenses have been widely employed as an implantable probe, with the advantage of excellent stability, high resolution, and low cost. In addition, a potential strategy for implantable imaging of the brain in vivo involves using a single multimode fiber, based on modulation of the light field, to focus and scan spot at the end of multimode fiber. This reduces tissue damage, with resolution at the cellular level. Herein, the recent progression of implantable fluorescence endoscopic microscopy is reviewed based on both GRIN lens and a single multimode fiber, besides application research in vivo including blood velocity, neurons growth, calcium ion conduction, and so on. Finally, fluorescence endoscopic microscopy imaging technologies for clinical diagnosis of brain tumors are also introduced, demonstrating that these advanced optical imaging methods expand the toolbox for brain science research and disease diagnosis.Conclusions and ProspectsEndoscopic probes have been miniaturized, providing greater flexibility while maintaining high performance; thus, probes can be implanted at different depths in the living brain to carry out functional modulation studies in specific deep brain regions. With micromachining or adaptive optics technologies, GRIN lens provides an effective method to obtain high resolution images. Although the nonmechanical scan imaging through a single multimode fiber is a relatively new exploration for brain research in vivo, it has already exhibited the unique advantages of minimally invasive and flexibility. In future, the following considerations are worth exploring: (1) development of a high-performance multimode fiber with enhanced anti-interference ability to external disturbances; (2) processing of a microlens on the face of multimode fiber with precise 3D printing technology, to optimize imaging resolution, depth of field, and field of view; (3) introduction of fluorescence polarization and fluorescence lifetime imaging modes to analyze neuronal physiological information, such as protein dipoles and cellular microenvironment.

ConclusionsIn this paper, we describe an innovative PACT image reconstruction algorithm based on DI-Net, a dual-domain neural network. Both numerical simulations and in vivo experiments are used to evaluate the performance of the proposed DI-Net. The imaging results reveal that DI-Net can effectively suppress streak-type artifacts caused by undersampling and the reconstructed images are comparable with the reference image. The imaging results also demonstrate that the proposed DI-Net provides better image quality compared with the widely-used FBP algorithm and the popular Post-Unet algorithm.

ConclusionsIn this study, we investigate the dynamics of laser-induced bubble pairs with variable relative interval. The bubble pair oscillation process significantly varies with relative interval. For a noncoalesced bubble pair, the oscillation is nearly spherically during the first period, but both of their oscillation processes are prolonged. For a coalesced bubble pair, the smaller the relative interval, the more spherical the bubble shape during its first period. The first oscillation period is longer than that of every single bubble and unaffected by the relative interval when it is less than 0.75. Besides, the evolution of coalesced bubble could still be described by Rayleigh-Plesset model. However, the relative interval of bubble pairs significantly influences the collapse shock wave emission and rebound bubble generation after the collapse of the coalesced bubble. The findings of this study are expected to facilitate the applications of laser-induced bubbles in microfluidic operations, such as rapid mixing and cell sorting.

ConclusionsBased on the near-field optical fiber temperature probe, a nondestructive cell temperature measurement method is proposed. The probe has a temperature sensitivity of 0.16 nm/℃. To achieve nondestructive scanning, the distance between the probe and the sample surface is maintained constant during scanning via feedback control of the tuning fork. At the same time, the probe measures the sample temperature through the response of fluorescence collected by the probe to the temperature change. Both the fixed U87MG cell with gold nanoparticles and the living U87MG cell without gold nanoparticles are measured using the near-field optical fiber probe. A maximum temperature difference of 4 ℃ is measured on the fixed cell surface, and 0.5 ℃ is measured on the living cell surface. The cells have the same morphology before and after scanning, indicating that the probe has caused nondestructive damage. The temperature measurement method proposed in this study, when combined with the temperature sensitivity and liquid environment stability of quantum dots fluorescence, as well as the nondestructive property of near-field optical technology, presents a better method for the nondestructive study of living cells.

ConclusionsIn this paper, based on the contradictions among the scanning range, imaging speed of traditional photoacoustic microscope, and the prospect of miniaturization, a photoacoustic microscope based on a transparent transducer is proposed, and a series of works such as hardware design, software development and simulation experiment of the system are completed. On the basis of the traditional photoacoustic microscope, our laboratory independently develops a transparent ultrasonic transducer to optimize the optical path of the system. A set of photoacoustic microscope based on the transparent ultrasonic transducer is designed. The lateral resolution of the system is 18 μm and the signal-to-noise ratio is up to 38 dB, which both give a large imaging field of view and a fast imaging speed. A single imaging can achieve 16 mm×16 mm range. The laser repetition rate of the system is 5 kHz and the imaging speed of 100 Hz/mm can be achieved when the scanning step is 20 μm. At the same time, the vascular morphology in the biological tissue imaging experiment is consistent with that in the photos, suggesting that the system has the potential to be applied in the biomedical field. Above all, the photoacoustic microscope based on a transparent transducer can give consideration to both a large imaging field of view and a fast imaging speed, and has a good application prospect in system miniaturization and functional imaging of biological tissues.

SignificanceThe incidence and mortality rates of digestive tract cancers are rising quickly globally, greatly endangering human life and health. Most digestive tract tumors come from precancerous lesions, and the development of early cancer detection and diagnosis technology is crucial to improving people’s health. To date, histopathological examination is still the "gold standard" for the clinical diagnosis of cancer, but this method has limitations, such as time-consuming and in vitro detection. Additionally, while biopsy sampling can examine the pathological characteristics of the suspected lesion area at the cellular scale, it cannot achieve full coverage of the suspected lesion area, so there is a certain risk of missed detection and false detection. Therefore, there is an urgent need to develop real-time, in vivo, in situ histological diagnostic techniques at the cellular scale to achieve early diagnosis of GI (gastrointestinal) cancers.Two-photon endomicroscopy is a new type of endomicroscopic imaging technology based on the principle of two-photon excitation, with the technical advantages of optical-sectioning capability, deep penetration, low phototoxicity, and label-free imaging. This technique can realize structural imaging and functional imaging, which has great potential for applications in life science and clinical medicine.Piezoelectric ceramic scanning two-photon endomicroscopy is the current preferred solution for two-photon endomicroscopy imaging technology. In recent years, this technique has achieved technological breakthroughs and new applications. This paper summarizes piezoelectric ceramic scanning two-photon endomicroscopic imaging technology and the research progress and introduces its application in the field of biomedical imaging.ProcessSection 2 introduces three typical two-photon endomicroscopy systems: fiber bundle proximal scanning scheme, MEMS distal scanning scheme, and piezoelectric ceramic-driven fiber distal scanning scheme (Fig. 1). Subsequently, the system structure and breakthroughs in core device technology of piezoelectric ceramic scanning two-photon endomicroscopy in recent years are summarized (Fig. 2). It mainly includes low-dispersion low-loss transmission double-cladding fiber, high-imaging resolution miniature objective, and high resonant frequency piezoelectric ceramic fiber scanner.On this basis, we introduce in Section 3 the recent research progress of the representative piezoelectric ceramic scanning two-photon endomicroscopy in this field. In the abroad research progress, the works from the following research groups are summarized, including Chris Xu’s group from Cornell University (Fig. 3), Frédéric Louradour’s group from Université de Limoges (Fig. 4), Xingde Li’s group from Johns Hopkins University (Fig. 5), Ki-Hun Jeong’s group from the KAIST (Fig. 6), and a joint team of Bernhard Messerschmidt’s and Juergen Popp’s groups from the GRINTECH and the Leibniz Institute of Photonic Technology, respectively (Fig. 7). In the domestic research progress, the work from the following research groups is summarized, including Ling Fu’s group from the Huazhong University of Science and Technology (Fig. 8), and a joint team of Lishuang Feng’s and Aimin Wang’s groups from the Beihang University and the Peking University, respectively (Fig. 9). It can be concluded that the capability of this technology for in situ, real-time, noninvasive, and high-resolution structural and functional imaging of biological tissues and organs has been fully verified. A part of the research units continues to focus on the research of a two-photon endomicroscopy integrated probe. The capability of the piezoelectric ceramic scanning two-photon endomicroscopy technology can be improved further by optimizing the core device and introducing new principles and methods; parts of the research units have conducted the development of a miniaturized endomicroscopy system to meet the clinical biosafety and compatibility requirements and develop its application in the biomedical imaging field.In Section 4, we summarize two-photon endomicroscopy applications in structural and functional imaging of tissues and brain imaging of freely-moving animals. The following research groups’ work, including Xingde Li’s group from the Johns Hopkins University [Fig. 10 (a)-(i) and Fig. 12], a joint team of Liwei Liu and Junle Qu’s group from Shenzhen University [Fig. 10 (j)-(r)], and Heping Cheng’s group from the Peking University (Fig. 11), is summarized.Conclusions and ProspectsAs a subcellular-scale optical biopsy technology, two-photon endomicroscopy can achieve real-time structural and functional imaging of biological tissues in situ, which has important scientific research value and broad clinical application prospects. The following recommendations are considered for the future development of two-photon endomicroscopy: 1) further breakthroughs in core device performance to improve the imaging capability and throughput of piezoelectric ceramic scanning two-photon endomicroscopy; 2) research on two-photon endomicroscopy technology based on MEMS scanning mirrors; 3) research on disposable endomicroscopy technology; 4) exploration of two-photon imaging technology-based multimodal imaging technology. It is foreseeable that piezoelectric ceramic scanning two-photon endoscopic imaging technology, as one of the important research directions of two-photon imaging technology, is expected to open a new paradigm of optical biopsy imaging applications for life science research and clinical medicine applications.

SignificanceOver the past few decades, endoscopes have been used to view the interior of cavities in the human body or the surfaces of internal human organs noninvasively for diagnosis or treatment. However, white light endoscopy and magnifying endoscopy widely used in clinical practice have poor resolution and contrast and require pathological biopsy examination to confirm the diagnosis. In recent years, narrow-spectrum technology has used blue light via optical or digital filtering to irradiate tissues and enhance the microstructural and microvascular morphology of the mucosal surface, improving the imaging contrast. However, it still exhibits poor resolution. White light and narrow-spectrum endoscopy cannot achieve cellular-level resolution; therefore, a purely optical biopsy cannot be performed, significantly reducing diagnosis accuracy. Confocal endoscopy has emerged owing to its submicron resolution and optical sectioning capability. Cell morphology observed using confocal endoscopy is highly consistent with the biopsy pathology. Since its introduction in 2004, confocal laser endomicroscopy (CLE) has become a vital technique in gastrointestinal endoscopic imaging. Confocal laser endoscopy enables endoscopists to perform cellular imaging and tissue structure assessments at the focal plane during endoscopic testing. Thus, real-time in vivo histological information can be obtained, enabling "optical biopsy."ProgressConfocal microscopy was first developed in 1957 by Minsky, who used pinholes on the illumination and detection sides in the same conjugate image plane to achieve "confocal." In 1967, Egger and Petrǎn successfully used confocal microscopy for label-free imaging of neural tissues. The key to confocal microscopy imaging technology is that the "double focus" of the two pinholes can shield all signals from the nonfocal plane, and the photomultiplier tube behind the detection pinhole can detect only the signal from the focal plane to achieve optical sectioning. Depending on the source of the image contrast, laser scanning confocal microscopy can be performed in the fluorescence or reflectance mode. Fluorescence confocal microscopy requires fluorescent contrast agents to generate contrast, yielding spatial and functional information about endogenous autofluorescence and exogenously labeled molecules and structures. Reflection confocal microscopy relies on differences in the refractive indices of cellular structures to generate natural contrast.Based on the scanning method, confocal endoscopy in confocal endoscopic imaging technology is divided into endoscopy-integrated and probe-based confocal endoscopy. As shown in Figure 2, the endoscopy-integrated confocal endoscope adopts the distal scanning mode [Fig. 2(b)], whereas the probe-based confocal endoscope adopts the proximal scanning mode [Fig. 2(a)]. The eCLE uses a point-scanning method to drive a single optical fiber to scan through a scanning device, achieving high-resolution confocal endoscopic imaging. Because the eCLE adopts a distal scanning method and the mechanical scanning device is included in the imaging probe, it is necessary to miniaturize the mechanical scanning device. However, the miniaturization of this device required for confocal endoscopy is technically challenging and expensive. Therefore, eCLE is limited to clinical applications because of the limited size of the mechanical scanning device. The pCLE probe does not contain a scanning device, and the scanning device does not have size limitation. However, its resolution is limited by the distance between the cores, and the imaging quality is affected by the honeycomb structure of the fiber bundle.As both eCLE and pCLE are based on traditional confocal microscopy imaging techniques, they use a single excitation wavelength. However, the traditional confocal endoscope requires mechanical scanning to complete three-dimensional imaging, and the imaging speed is low. Therefore, traditional confocal endoscopic microscopy-imaging solutions cannot achieve rapid three-dimensional deep tissue imaging or real-time optical diagnosis in clinical practice. Spectral-encoded confocal microscopy (SECM) is a reflection confocal microscopy technique. It can be used to determine the spatial position of a sample by measuring the spectrum of light reflected from the sample. It can significantly increase the confocal imaging speed, enabling large-area imaging within a short time. The high imaging rate of SECM can potentially increase the confocal field of view, but the imaging depth of the focus is still limited to 200 μm. At more significant imaging depths, the effective resolution of SECM is significantly reduced owing to light scattering and optical aberrations.In recent years, chromatic confocal technology has been used to achieve high-resolution, fast, and multi-depth imaging. Chromatic confocal endoscopy solves the problem of insufficient imaging depth in traditional confocal endoscopy, and shows significant potential in gastric cancer diagnosis. However, it cannot guarantee large chromatic and small spherical aberration simultaneously in miniaturization, owing to the limitations of lens-manufacturing technology, resulting in limited axial resolution.Confocal endoscopes enable in vivo and real-time imaging of different tissues, cells, molecules, and even bacteria owing to the higher magnification and resolution of confocal endoscopes than those of conventional endoscopes. In particular, confocal endoscopic imaging technology has promising applications in diagnosing diseases in the human body, such as the gastrointestinal tract, skin, cervix, and eye.Conclusions and ProspectsIn this paper, confocal endoscopic imaging technology is briefly described. A comparative introduction is presented for fluorescence confocal imaging, reflectance confocal imaging, and probe-based and endoscope-integrated confocal endoscopic imaging. Furthermore, the application of confocal endomicroscopy in biomedical science is discussed.

SignificanceLaser has the advantages of high brightness, directivity, energy, and beam quality. In recent years, laser technology has been widely used in industrial sensing, communication, and medical treatment, particularly in treating vascular diseases. Thrombosis is a serious vascular disease with a complicated pathogenesis. Thrombosis can cause blood clots in blood vessels, resulting in insufficient blood supply to vital organs. Ischemic stroke is an acute cerebrovascular disease, mainly occasioned by atherosclerosis of the arteries supplying blood to the brain, which in turn results in blockage of blood vessels and insufficient blood supply to the brain; long-term obstruction can lead to brain tissue necrosis. If a blood clot flows into the heart, it can cause a myocardial infarction. Moreover, if lower extremity thrombosis is serious, it can cause a blood circulation disorder at the end of the extremity and even gangrene. Venous vascular injury, endothelial dysfunction, and slow blood flow are all critical factors in developing deep vein thrombosis. Severe consequences of deep vein thrombosis can lead to pulmonary embolism and amputation. Therefore, thrombus is a vascular disease that seriously endangers human life, health, and safety, and its treatment is the fundamental method for recovery.The rapid development of laser technology has promoted research progress in laser medical treatment. In particular, pulsed laser has broad application prospects in the fields of industry, medicine, and communication owing to its high repetition rate, energy peak power, and beam quality. The effect of laser on thrombus is mainly realized by the photothermal, photochemical, and photomechanical effects between the thrombus and biological tissue to achieve laser thrombolysis. Laser thrombolysis has the advantage of accurate localization, which can eliminate the thrombus at the site of the blood vessels, restore blood flow, avoid severe injury caused by surgery, and reduce postoperative complications. Because the ablation time is short, postoperative patients recover quickly and reduce hospital stay and medical costs. Therefore, the study of laser thrombolysis is of great significance.ProgressWith the development of laser technology and the continuous improvement of the interaction mechanism between laser and biological tissue, the application of laser in thrombus ablation has progressed in some aspects. With the same sample and conditions, the thermal cautery of continuous-wave laser to tissue is significantly higher than that of a pulsed laser. Hence, a pulsed laser is mostly used in laser thrombolysis to avoid unnecessary damage to surrounding tissue. Optimization of pulsed-laser parameters—such as wavelength, pulse width, power, and energy—is the future development direction of pulsed-laser thrombolysis. Furthermore, in laser thrombolysis, the direct use of bare optical fibers to generate laser has certain adverse effects on biological tissues, whereas the use of radial fibers requires lower energy, which significantly reduces the adverse effects. Consequently, various launch fibers have been developed. Moreover, laser thrombolysis combined with various other thrombolysis methods, such as mechanical thrombectomy, can increase the success rate of surgery and reduce the recurrence rate of restenosis, which is of great significance for thrombolysis. In-vitro and clinical tests have shown that the light emitted by 308 nm and 355 nm excimer lasers is a cold light source that generates less heat and penetrates less deeply into tissues, especially for calcified thrombus. Several studies support this conclusion. The use of multiple laser wavelengths to ablate thrombi has also been verified by various experiments. Different wavelengths of lasers absorb different tissue components differently and have specific ablation effects on different thrombus types and sites. Therefore, many research institutions have studied and developed multi-band laser thrombolytics.Conclusions and ProspectsThis paper reviews the application status of laser in the treatment of thrombosis, mainly from in-vitro and clinical settings. Further, it summarizes the application progress of laser thrombolysis and the possible future development direction. Currently, research on laser medical treatment is developing in the direction of multi-band and multi-application fields. Meanwhile, laser technologies such as multi-fiber and multi-diameter types are being developed to reduce the incidence of complications. For excimer lasers, realizing high power, full fiber structure, and low cost is the main research prospect. Moreover, deepening the research on the mechanism of interaction between laser and tissue while understanding every process and stage of organizational change can optimize the laser parameters to realize real-time adjustment and dynamically control the process of laser thrombolysis. This forms an essential part of theoretical research to guide the actual application process.

ConclusionsCA-RepVGG can be used in clinical practice. The simplicity of the model and the small amount of calculation ensure the feasibility and reliability of CA-RepVGG. In this paper, CA-RepVGG is used to test and evaluate the classification effect of DR images in two datasets. At the same time, VGG-16, Inception-V3, ResNet-50, and ResNext-50 are compared with our model, and the accuracy, precision, and sensitivity of the network demonstrate the advanced nature of our model. The experimental results show that the model is not only feasible but also superior in classification. In the future, if our proposed model is applied to clinical practice, it can enhance the diagnostic efficiency of professional ophthalmologists regarding ophthalmic diseases, especially in remote and poor areas, ensuring that more patients can be treated in time and avoid losing their eyesight. If more datasets can be used to train the model in the future, the accuracy of automatic classification can be further enhanced and better results can be achieved in clinical practice.

Objective Embryonic development has attracted increasing attention in biological research. Monitoring the internal organs and tissues of an embryo is relevant to the study of embryonic development. Generally, two methods are employed to monitor tissues in the embryo: tissue section technology and stereomicroscope observation. Both methods need to kill the embryo and cannot monitor a single living embryo continuously. Therefore, noninvasive real-time monitoring of embryonic development is expected to understand the morphological evolution process. Optical coherence tomography (OCT) is a relatively novel imaging method in the 21st century and is based on the principle of low coherence interference. It uses near-infrared light to scan the sample noninvasively, and then a three-dimensional image reconstruction is performed. OCT can provide internal structure information with a depth of 1--12 mm below the sample surface. Several research groups have reported studies on the embryonic development of different animals, such as Xenopus, mice, and birds, using OCT. However, there are few reports on the application of OCT to insect embryonic development. The main reason is that insect embryos are usually wrapped with eggshells that protect the embryo from external damage. This morphology of the insect embryo significantly affects the real-time monitoring of its development. Therefore, a method that can automatically identify the edge and thickness of the eggshell and intelligently erase it is required.Methods An image processing method is proposed in this paper to eliminate the effect of eggshells on OCT imaging. This method can automatically identify and erase the area of the eggshells so that the clear three-dimensional image of the embryo inside the eggshell is presented. As shown in Fig.1, first, the three-dimensional image is filtered to reduce noise; second, local threshold segmentation and boundary recognition are performed; and then the position and thickness of eggshells can be extracted and erased in the original image. Afterward, the three-dimensional image of the embryo phenotype can be presented. Noise is often introduced during the real-time OCT image acquisition process, which can severely influence the effect of eggshell edge detection. Therefore, the original three-dimensional image denoising is an indispensable operation in image preprocessing. After comparing various image-denoising methods (Fig.2), the median filtering is selected. Figure 5(b) shows that the contrast is higher between the eggshell edge and the internal structure after noise reduction. However, the inner boundary of the eggshell is still connected with the yolk and embryo, which can cause measurement error when extracting the thickness of the eggshell. Therefore, local threshold segmentation is employed to solve the problem, and detailed procedures are shown in Fig. 4. Figure 5(c) shows the binary image in which the grey value of the eggshell is 255, whereas, other regions are 0 after local threshold segmentation. Hence, the first junction between 255 and 0 is the outer boundary of the eggshell, and the second is the inner boundary. Thus, the location and thickness of the outer and inner boundary of the eggshell can be obtained by counting the number of pixel points with a grey value of 255 between the two junctions in each A-scan image. Notably, the eggshell edge is non-smooth after local threshold segmentation. Consequently, the second filtering is used to smoothen the edge, which ensures accurate measurements.Results and Discussions Figure 6 shows the comparison of OCT imaging results before and after eggshell removal on the 11th day of locust egg development. As shown in Fig. 6 (a), the internal morphology of the embryo is covered by eggshell and is not visible. After using the eggshell removal method to process the image, the head, antennae, abdomen, and feet of the embryo are clearly seen in the three-dimensional projection of XY [Fig. 6(b)]. Figures 6 (c) and (d) are two-dimensional cross-sectional images of XY with depths of 0.67 and 0.88 mm, respectively. Although these cross-sectional images are not affected by the eggshell, they cannot reflect the overall changes of the embryonic development morphology and are significantly different from the three-dimensional image of Fig. 6(b). By contrast, Fig. 6(b) is a suitable three-dimensional image to study embryonic development. Therefore, this is the purpose and significance of the eggshell removal method proposed in this paper. Equipped with the eggshell removal method, Fig. 7 shows the embryonic development process observed on days 6 to 14 clearly.Conclusions Because the insect embryo is wrapped by an eggshell, the three-dimensional OCT image cannot directly show the whole morphology of the embryo inside the egg. Therefore, in this study, we propose an image processing method to eliminate the effect of eggshell on OCT imaging. This method can automatically determine the boundary and thickness of eggshell and erase it. Compared with traditional invasive detection methods that are complicated in operation, time-consuming, and cannot continuously monitor a single living embryo, OCT has the advantages of noninvasive, real-time, and high-speed nature to obtain more accurate monitoring results of embryonic development. This image processing method is helpful to the application of OCT in the study of insect embryonic development.

Objective Port wine stain is a congenital skin disease mainly in the face and neck, which seriously affects the physical and mental health of patients. aiming to thermally damage the malformed capillaries through laser energy absorption by hemoglobin, pulse dye laser and alexandrite laser with wavelengths of 585/595 and 755 nm, respectively, are used to treat port wine stains clinically. However, there is competitive absorption of laser energy between epidermal melanin and dermal hemoglobin, which limits the increase of laser energy with a wavelength of 585/595 nm and the alexandrite laser with 755 nm for Asians. The core-shell Au nanoparticle (NP) can be used to enhance the laser energy absorption by blood due to its adjustable absorption peak to a specific wavelength by changing its structural parameters and distinctive photothermal absorption. In this work, the effects of the structural parameters (particle radius, the thickness of the gold shell, and interparticle distance) on the photothermal properties of a single particle and the dimer were studied theoretically under 585 nm and 755 nm wavelengths, which could provide theoretical guidance in the laser surgery of vascular dermatosis in a clinic.Methods The core-shell Au NP is immersed in water for nanoscale heating. The simulation calculations of the electromagnetic field propagation and the heat transfer among different media are resolved by the finite element method (FEM). For the electromagnetic simulation, first, the basic properties of each domain, including the perfectly matched layer (PML) and scattering boundary condition, are strictly defined. Then, the properties of the electromagnetic waves in the domain are set, including the incident direction and intensity. The electric field vector solution of the core-shell NPs mediated by the plane wave is obtained by solving the Helmholtz equation of SiO2@Au core-shell NP. Based on the solved electric field vector solution, we could analyze the influence of structural parameter changes on the local electric field distribution. The light energy absorbed by NPs was converted into heat energy by the Joule heating effect. For the heat transfer simulation, by solving the three-dimensional steady-state heat conduction equation with the heat source supplied by light energy absorption under the third thermal boundary condition, we could obtain the effect of structural parameter changes on the temperature-rise distribution. Before calculation, the solved domains are meshed.Results and Discussions For the single NP, when the particle radius r is constant under λ=585 nm, with an increase in the thickness of the Au shell s, the maximum electric field intensity |E/E0|max and the temperature-rise DTmax, which are mainly affected by the number of internal free electrons and the average-free path, increase first and then decrease (Fig. 3); When the thickness of Au shell s is constant under λ=585 nm, as particle radius r increases, |E/E0|max and DTmax—which is mainly affected by the phase delay effect and the number of effective free electrons—have no obvious regular pattern. Meanwhile, for λ=585 nm, when r=32.5 nm, s=12 nm, |E/E0|max and DTmax are 12.4 and 106.5 K, respectively. For λ=755 nm, when r=35 nm, s=5 nm, |E/E0|maxand DTmax are 1.93 and 1.32 times of the corresponding value of the λ=585 nm case, respectively (Fig. 5). In addition, compared with the corresponding value of the λ=585 nm case, when the thickness of the Au shell is thinner, the photothermal properties of the particle are better. The effects of interparticle distance l= 0--100 nm on the electric field intensity |E/E0| and temperature-rise field DT distribution of the dimer are studied when λ=585 nm (setting each single particle as follows: r= 32.5 nm, s=12 nm). When l=0 nm, |E/E0|max and DTmax are in the central point, whereas for l=60 nm, |E/E0|max and DTmax are in a single particle surface and interior, respectively (Figs. 6 and 7). Besides, l has different effects on |E/E0|max and DTmax of the dimer. When lE/E0|max decreases sharply with the increase in l. When l>60 nm, as the optical properties of the dimer are similar to that of single NPs, |E/E0|max stops changing. For the temperature-rise field, when lE/E0|max with the increase in l, the absorption thermal power density Qr and DTmax decrease rapidly. When l>10 nm, although |E/E0|max decreases, the isobaric coupling effect of a single particle increases gradually, so DTmax increases continuously. When l>60 nm, the temperature-rise distribution is similar to that of a single particle and becomes stable (Fig. 8).Conclusions For a single core-shell Au NP, when the particle radius r is fixed under λ=585 nm, as the thickness of the gold shell increases, |E/E0|max and DTmax increase first and then decrease. In addition, for λ=585 nm, when r=32.5 nm and s=12 nm, |E/E0|maxand DTmax are 12.4 and 106.5 K, respectively. For λ=755 nm, when r=35 nm and s=5 nm, |E/E0|maxand DTmax are 1.93 and 1.32 times of the corresponding value of the λ=585 nm case, respectively. Besides, compared to the corresponding value of the λ=585 nm case, when the shell thickness is thinner, the photothermal properties of the particle are better. While for the dimer, l has different effects on |E/E0|max and DTmax; when lE/E0|max and DTmax decrease, while for l>10 nm, although |E/E0|max decreases, DTmax increases continuously and finally becomes stable.

Objective Recently, researchers increasingly focused on air quality. The air microorganisms cause severe harm to human health and severe effects on some industrial production. The latest national standard “Public Places Hygiene Indicators and Limits Requirements” stipulates the total number of air bacteria. Microbial detection based on fluorescence technology is widely used in medicine, pharmaceuticals, food, and environmental monitoring. The detection technologies include real-time fluorescent quantitative polymerase chain reaction (PCR), adenosine triphosphate (ATP) fluorescence detection, and microbial particle fluorescence-sensing system. The fluorescent microbial particle counter can directly count microbial particles, which has some advantages of good real-time performance, a high degree of automation, and simple operation. Besides, it is suitable for real-time online monitoring of the concentration of air microorganisms. This study designs a optical system based on the fluorescence detection principle in microbial particle counter to realize the online monitoring of microbial particles.Methods The optical system is designed based on the fluorescence detection principle. In this study, the fluorescence characteristics of riboflavin, nicotinamide adenine dinucleotide, and other substances contained in microbial particles were tested and analyzed at first. Then, a 405 nm wavelength semiconductor laser was determined as the excitation light source. To reduce the output stray light of the laser, the light source shaping and fluorescence detection optical paths based on the combined diaphragm and lens were designed to obtain a high-quality flat rectangular line spot. Subsequently, consisting of oxidized and blackened aluminum alloy, the optical detection cavity structure were designed in the shape of hexahedron, and the production and assembly of the inspection structure were completed. Finally, the performance of the optical detection system was tested and analyzed using fluorescent microspheres in different particle sizes.Results and Discussions In this study, the fluorescence detection and analysis of two fluorescent substances, riboflavin and nicotinamide adenine dinucleotide, were first conducted. Under the excitation of blue light of the same wavelength, the fluorescence peak position of riboflavin is 541 nm [Fig. 1(a)]. The peak position of the fluorescence spectrum of adenine dinucleotide is 492 nm [Fig.1(b)]. Then, fluorescent microspheres were used to test the performance of the designed optical detection system. The results showed that the final output noise of the system was is about 20 mV [Fig. 8(c)], and it could achieve graded detection of 10, 5, 2, and 1 μm fluorescent microspheres. The test voltage signal of 10, 5, 2, and 1 μm fluorescent microspheres has a signal amplitude of 350--380 mV (Fig. 9), 250--290 mV (Fig. 10), 130--140 mV (Fig. 11), and 78--90 mV (Fig.12), respectively. The test results showed that the optical detection system can effectively detect the signals of fluorescent microspheres of different particle sizes and has the characteristics of high signal-to-noise ratio and high detection sensitivity, which is of great significance for the further development of aerosol microbial particle counting instruments.Conclusions In this study, an aerosol microbial particle counting instrument optical system based on fluorescence detection technology was designed. The overall structure of the instrument optical system was proposed. Besides, the design and structure manufacturing of the optical system were completed. By designing optical denoising optical path, optical noise is effectively suppressed, and the system signal-to-noise ratio is improved. Combined with the second-order RC low-pass filter circuit, the final noise of the system is only about 20 mV. The performance of the detection system was preliminarily tested with 10, 5, 2, and 1 μm fluorescent microspheres. The measured pulse signal amplitudes were 350--380 mV, 250--290 mV, 130--140 mV and 78--90 mV; system detection resolution is better. Next, some microbial samples, such as Staphylococcus aureus and Escherichia coil will be tested, and further the structure will be optimized to complete the overall design of the instrument.

Objective To overcome the ill-posedness of the bioluminescence tomography (BLT) reconstruction problem and obtain stable reconstruction results, researchers combined different prior information and regularization techniques to design various reconstruction algorithms. Among them, biological tissue structure information, a permissible source region, multi-spectral measurement information, and light source distribution sparseness are priori information widely used in reconstruction. The reconstruction algorithm based on regularization is divided into convex and non-convex optimization methods according to whether the objective function is non-convex. Although the regularization models of these reconstruction algorithms are different, the regularization parameter play a significant role in the reconstruction process, which directly affects the reconstructed image quality. Thus, the selection of the optimal parameters has always been a challenging problem for research. In this study, we proposed a multi-spectral BLT reconstruction method based on primal dual active set with continuation (PDASC) algorithm. The proposed method combines the primal dual active set (PDAS) algorithm with continuity technology, which can automatically adjust the regularization parameter to obtain a globally optimal solution.Methods In this study, the iterative algorithm, PDASC, contains inner and outer iterations. The inner iteration part is the PDAS algorithm, which determines the active set based on the primal and dual variables. It then updates the primal and dual variables by solving the least square problem of the active set. The outer iteration combines the continuity technology of the regularization parameter. In the PDASC algorithm, the stopping criterion in the continuity technology directly affects the determination of the regularization parameter. Thus, it is essential to select an appropriate stopping criterion. If the noise level is known, we can choose the deviation principle as the stopping criterion. However, it is not easy to accurately estimate the noise level in actual situations. Thus, we choose the Bayesian information criterion that can adjust the regularization parameter to control the size of the active set and obtain a globally optimal solution.Results and Discussion To verify the performance of the proposed PDASC algorithm in BLT, we designed multiple sets of simulation experiments compared with PDAS and HTP algorithms on the digital mouse model. The proposed algorithm was further examined with a mouse in vivo experimental data. The simulation results of the non-homogeneous digital mouse model showed that the Dice coefficient based on the PDASC algorithm can reach or exceed 65%, the positioning error is within 0.9 mm, and the contrast noise ratio is greater than 16.52 in single and double light source experiments (Table 2 and Table 3). These quantitative indicators validate that PDASC algorithm has the smallest reconstruction error, the highest quality of the reconstructed image, and the best reconstruction results of the shape and volume of the real light source (Table 2 and Table 3). For the double-source case, the PDASC algorithm has the highest shape fit of the reconstructed image and the best source-resolving ability (Fig. 5). The performance of PDASC algorithm on the three indicators for the in vivo experiment is also consistent with the simulations (Table 4). Above results indicate that the proposed PDASC algorithm is promising in practical tumor detection applications.Conclusions In this study, we proposed a multi-spectral BLT reconstruction algorithm based on primal dual active set with continuation. The proposed algorithm combines the PDAS with the continuation technology for the regularization parameter, which can automatically adjust the regularization parameter to obtain the global optimal solution. Besides, the use of multi-spectral information reduces the ill-posedness of reconstruction. Multiple sets of simulations on a digital mouse confirm the effectiveness and stability of the proposed algorithm. The in vivo experimental results show the potential of the algorithm in practical applications. Although the proposed algorithm is better than the compared algorithms, it cannot fit the shape or contour of the light source perfectly. With the continuous development of deep learning, deep imaging algorithms have also appeared in the field of optical molecular imaging. Most of these algorithms are currently based on end-to-end neural networks, such as K-nearest neighbor local connection network, 3D deep encoder-decoder network, and stacked auto encoders neural network. By establishing the nonlinear mapping relationships between surface fluorescence and light source distributions, the deviation caused by the simplified linear model is avoided. However, the size of the training dataset, which plays a significant role in the depth imaging algorithm will directly affect the reconstruction performance. Thus, the focus of our future study is to determine how to combine the model with the network to solve the ill-posedness of BLT reconstruction.

Objective Skin cholesterol is an important biomarker for early atherosclerosis screening. Atherosclerosis is the leading cause of disability and death from cardiovascular disease. Effective control of pathogenic factors in the early pathological stage may delay or prevent the development of asymptomatic atherosclerosis into cardiovascular diseases. Thus, skin cholesterol detection becomes relevant in the prevention of cardiovascular diseases. Traditional skin cholesterol detection methods, such as skin biopsy or tape stripping, are invasive and usually time consuming. Alternatively, the recent three-drop method is being widely studied. In this method, three specific concentrations of reagents that bind to skin cholesterol are used on the skin surface of a subject, and atherosclerosis can be diagnosed by analyzing the reagent color changes. However, the three-drop method is sensitive to the application habits of the operator. Moreover, the detection reagents contain enzymes, polymers, and small molecule compounds, hindering quality control and increasing the sensitivity to environmental factors such as temperature and pH levels. We report a non-invasive skin cholesterol detection technique based on fluorescent spectrometry. By measuring the fluorescence spectrum of fluorescent-labeled skin, the cholesterol content can be calculated from the fluorescence spectra. This method corrects the influence of temperature on the test results and provides stability under various environmental conditions. Moreover, the skin cholesterol content can be obtained within 4 minutes. The proposed method provides a rapid non-invasive and stable method for skin cholesterol detection and corresponding applications including early atherosclerosis screening.Methods The proposed non-invasive skin cholesterol detection system is composed of a light source, fiber probe, spectrometer, photodiode, infrared temperature sensor, and computer. The fluorescence fluctuation of the detection reagent caused by temperature variation is corrected by establishing the relation between temperature and the fluorescence intensity of the detection reagent. To confirm the accuracy of the proposed skin cholesterol detection system, we extract skin cholesterol with absolute ethanol after the non-invasive measurement. The cholesterol content in the extraction liquid is determined by gas chromatography, and the correlation between the two results are analyzed. Finally, the clinical applicability of the proposed system is confirmed by measuring skin cholesterol content from both healthy subjects and subjects with high risk of presenting atherosclerosis.Results and Discussions The schematic of the proposed non-invasive skin cholesterol detection system based on fluorescent spectrometry is shown in Fig. 1. The system accurately detects skin cholesterol content after correcting for temperature. The average fluorescence intensity of the detection reagent in the 462--520 nm wavelength band decreases with increasing temperature, resulting in a significant negative correlation between fluorescence intensity and temperature (r=-0.995, pp=0.0004) (Fig. 7). The proposed non-invasive skin cholesterol detection system can screen subjects with high risk of presenting atherosclerosis. Nevertheless, clinical trials are required for verification given the small sample size used in this study.Conclusions We propose a rapid non-invasive detection system for skin cholesterol based on fluorescent spectrometry. The system quickly provides the skin cholesterol content on-site from the fluorescence spectrum of detection reagents that specifically bind to skin cholesterol. The proposed system performs temperature correction to prevent deviations of the measurement results and improve accuracy and stability. The system and its detection accuracy are verified through comparisons with skin cholesterol results obtained from gas chromatography. The proposed system may be used to screen people with high risk of presenting atherosclerosis by detecting skin cholesterol content in healthy subjects and subjects at high risk. Overall, the proposed system can detect skin cholesterol accurately, non-invasively, and quickly. We expect that the widespread adoption of this technology will contribute to the prevention and control of cardiovascular diseases.

Significance Super-resolution microscopy overcomes the 200 nm spatial resolution limitation of traditional optical microscopy and has been widely used to image subcellular structures in living cells. Super-resolution microscopy mainly includes stimulated emission depletion (STED) microscopy, structured illumination microscopy (SIM), and single-molecule localization microscopy (SMLM). Super-resolution structured illumination microscopy (SR-SIM) is the most widely used super-resolution microscopy technique. Owing to the low phototoxicity, high-speed wide field of view, and multichannel three-dimensional super-resolution imaging capabilities, SR-SIM is especially suitable for real-time detection of dynamic fine structures in living cells. SR-SIM has high-speed wide-field imaging capabilities that enable rapid dynamic measurement of living cells. Compared with STED and SMLM microscopy imaging under a light intensity of ~1000 W/cm 2, SR-SIM allows imaging under a low light intensity of ~10 W/cm 2, which meets the requirement of long-term imaging of living cells. At the same time, multicolor and multichannel imaging by SR-SIM is beneficial to the study of molecular interactions. The super-resolution structured illumination reconstruction algorithm (SIM-RA) is the key to realizing fast, long-term, and nondestructive super-resolution imaging of SR-SIM. SR-SIM uses structured light in different directions and phases to excite the fluorescent sample for acquiring multiple original images with illumination patterns and then reconstructs a single super-resolution image through mathematical calculations. Owing to the imperfection of the experiment and the inevitable uncertainty in the measurement of experimental parameters, the estimation of the reconstruction parameters results in false signal and noise, which reduces the resolution of the SR-SIM image and introduces artifacts that can be misinterpreted as biologically relevant features. An excellent SIM-RA can improve the accuracy of reconstruction parameters and filter out noise to reduce artifacts and ensure image quality. In addition, a long exposure time will increase the phototoxicity and photobleaching, which is not conducive to the long-time observation of living cells. SIM-RA can reduce the exposure time by two orders of magnitude for the reconstruction of SR-SIM images, allowing the use of fewer original images to achieve SR-SIM image reconstruction, providing longer and faster super-resolution imaging. Initially, SR-SIM requires users to have professional knowledge. The development of SIM-RA makes it unnecessary to manually set parameters, automatically obtain reconstruction parameters and estimate their uncertainty, and thus to reconstruct super-resolution images with a considerably reduced threshold. The super-resolution structured illumination microscopic image reconstruction process requires strict analysis and calculation to ensure the final super-resolution image quality and imaging speed, which relies on an efficient and stable SIM-RA.In the past two decades, to achieve automatic, simple, and stable acquisition of high-quality and high-spatial-resolution reconstruction images, the development of super-resolution SIM image reconstruction algorithms has never stopped. Systematic summary and analysis of SIM-RA are necessary for users who want to construct a higher-performance super-resolution structured illumination microscopy system.Progress This article systematically elaborates and analyzes the reconstruction algorithm of super-resolution structured illumination microscopy. First, it briefly introduces the realization principles and respective advantages of the three super-resolution microscopy techniques, i.e., STED, SIM, and SMLM, and expounds the necessity of studying SIM-RA based on the characteristics of SR-SIM imaging. Second, it introduces the imaging principle of SR-SIM based on structured illumination in detail, and focuses on SIM-RA. In view of the possible reasons for the poor imaging quality caused in the SR-SIM image reconstruction process and the improvement of the algorithm for fast, long-term, and nondestructive imaging of SR-SIM, the calibration and parameter value acquisition algorithms of SR-SIM, SIM-RA, and SR-SIM toolbox are analyzed and summarized. Initially, Gustafsson extended the Wiener filter and applied it to SR-SIM image reconstruction to solve the problem of reconstruction artifacts. Compared with Wiener filtering, the R-L deconvolution algorithm reduces the influence of photon noise on the imaging results, and MAP-SIM further reduces the influence of noise by suppressing defocused light (Fig.4). System calibration before SR-SIM imaging helps reduce artifacts, and the accuracy of reconstruction parameters determines the quality of the reconstructed image. Using algorithms including iterative calculations to accurately determine reconstruction parameters such as illumination frequency and illumination phase is a prerequisite for achieving artifact-free SR-SIM imaging. The inversion of SR-SIM images based on Bayesian theory allows automatic acquisition of parameters and reduces the number of reconstructed original images, which is helpful for the realization of fast automatic imaging. The Hessian-SIM algorithm automatically filters the original image to reduce artifacts and uses methods such as rolling reconstruction to achieve fast and long-term imaging (Fig.5). To promote the development of SR-SIM, FairSIM and SIMcheck have been developed to provide general reconstruction algorithms. OpenSIM and SIMToolbox provide open-source codes to help researchers further study SIM-RA. In addition, machine learning is also used to achieve fast SR-SIM image reconstruction. At the end of the article, five problems to be solved in the current development of super-resolution structured illumination microscopy image reconstruction algorithms are summarized.Conclusion and Prospect The super-resolution SIM image reconstruction algorithm has a decisive influence on the imaging quality and imaging speed of super-resolution SIM. To achieve fast, stable, and automatic acquisition of high-quality, high-temporal-resolution super-resolution SIM images without artifacts, it is necessary to build better imaging algorithms. Excellent SIM-RA is necessary for reconstructing higher-resolution, faster, longer, and nondestructive SR-SIM images.

Objective The technique called flow-mediated NADH fluorescence measurement is used to reflect tissue microcirculation function, which has important value for early screening of cardiovascular disease. However, due to the obvious difference in the extinction coefficients of oxyhemoglobin and deoxyhemoglobin in the visible and near-infrared bands, the tissue absorption coefficient will change constantly during the blood flow-mediated process. The excitation light and emission fluorescence of fluorescent molecules are affected by the tissue absorption coefficient. The current flow-mediated tissue fluorescence detection technology only measures the change in total tissue fluorescence intensity during brachial artery occlusion and release and does not account for the interference of tissue absorption coefficient changes caused by changes in oxygen saturation on NADH fluorescence measurement. Therefore, this problem may directly lead to blood flow-mediated tissue fluorescence technology failing to achieve an accurate measurement, thus limiting the clinical application of the technology.Methods First, we created the flow-mediated tissue fluorescence measurement system. The tissue absorption coefficient was calculated using a combination of tissue fluorescence and diffuse reflectance measurements. To improve the detection system’s accuracy, a steady-state tissue intrinsic fluorescence recovery method was used to correct the interference of absorption coefficient changes during the process of brachial artery occlusion and release on NADH fluorescence measurement. Second, we carried out the validation experiments of biological tissue solid phantom with different optical parameters and blood oxygen phantom simulating the physiological process of brachial artery occlusion and release. Furthermore, we validated the flow-mediated tissue fluorescence measurement system’s accuracy by comparing the corrected and uncorrected changes in blood flow-mediated tissue fluorescence in normal subjects.Results and Discussions The results of tissue solid phantom experiments with different optical parameters showed when the values of α and β are 0.67 and 0.31, respectively, the small coefficient of variation of fluorescence intensity of the same concentration, the large linear correlation coefficient of gradient fluorescence intensity and concentration, and the closest curve shape could be satisfied at the same time (Fig.2). After obtaining the optimal combination of α and β , the fluorescence spectra of tissue phantom were recovered. The fluorescence intensity of NADH after recovery was linearly correlated with its concentration (R2=0.99), which indicated that the recovery effect was better (Fig.3). The results of blood oxygen phantom experiments showed that with the increase of sodium sulfite treatment time, oxygen saturation decreased significantly until stable. After being recharged, O2 returned to its baseline level and then decreased for the second time. The results demonstrated that the system could accurately extract the physiological parameters of a blood phantom. We found that changes in tissue oxygen saturation could interfere with NADH fluorescence detection, whereas the corrected intrinsic fluorescence spectrum of NADH was unaffected by changes in oxygen saturation (Fig.5). Finally, the blood flow-mediated tissue fluorescence system was used to measure the diffuse reflectance and fluorescence of four subjects during the brachial artery occlusion and release process. The low flow response (LFR) and high flow response (HFR) of four subjects were calculated separately. The results showed that the average values of LFR and HFR were 19.8% and 13.6%, respectively. In vivo experiments showed that after spectral recovery, the LFR and HFR decreased by 22.8% and 22.1%, respectively (Table 1). This change could be explained by the interference of oxygen saturation on the measured NADH fluorescence. Conclusions The extraction of tissue optical parameters and the recovery of intrinsic fluorescence in steady-state tissue fluorescence technology were introduced into flow-mediated tissue fluorescence measurement in this study to achieve the dynamic measurement of tissue intrinsic fluorescence spectrum in the blood flow-mediated process. The tissue phantom experiment of the distribution of different absorption, scattering, and gradient fluorescence characteristics was validated using the flow-mediated tissue fluorescence and diffuse reflectance measurement system. The results showed that the coefficient of variation of fluorescence intensity of tissue phantom with the same concentration of fluorescence components was approximately 36% under different absorption and scattering characteristics, whereas the coefficient of variation of intrinsic fluorescence intensity was less than 10%. The results demonstrated that the recovery algorithm reduced the impact of absorption and scattering properties on the detection of the intrinsic fluorescence spectrum. Furthermore, there was a significant positive linear correlation between the intensity of the intrinsic tissue fluorescence spectrum and the concentration of fluorescent components, indicating that the intrinsic tissue fluorescence spectrum could be used to detect fluorescent components quantitatively. The results of blood oxygen phantom experiments showed that the change of blood oxygen saturation would interfere with the fluorescence measurement, and the corrected tissue intrinsic fluorescence spectrum was independent of the change of oxygen saturation, which further verified the reliability of the algorithm. Finally, it was found through in vivo experiments that the blood flow-mediated tissue fluorescence may better reflect changes in NADH fluorescence in tissues by introducing the tissue optical parameters extraction and tissue intrinsic fluorescence spectrum recovery algorithm, which was expected to effectively improve the accuracy of this technology’s tissue microcirculation function evaluation.

Objective Vision loss is caused by age-related macular degeneration because of soft drusen, diabetic macular edema and choroidal neovascular disease. Early detection and treatment of these fundus diseases have emerged as a major health concern for all countries. Professional doctors often use retinal images from optical coherence tomography (OCT) to diagnose eye diseases. However, because there are several types of retinopathy images and the lesion area is similar, manually classifying OCT retina images is a time-consuming and difficult task. With the development of artificial intelligence, researchers began classifying medical images using classic machine learning algorithms and deep learning in its branch areas, eventually progressing to the automatic classification of OCT retinal images. Several researchers are only concerned with classification accuracy and ignore the possibility of clinical application. Consequently, the network model’s parameter amount, computational complexity and floating-point operations (FLOPs) calculation amount are increasing, and the model is making inference predictions, which consumes a long time to complete. In this paper, a multi-channel, multi-scale lightweight convolutional neural network is proposed to automatically classify OCT retinal images for achieving high ophthalmic disease classification accuracy. In the future, doctors will be able to quickly view detection results in the clinic.Methods In this study, a multi-channel OCT retinal image automatic classification deep neural network is used. The neural network model is based on the GM-OCTnet algorithm, which includes a light quantum spatial attention mechanism distinct from the convolution operator and a lightweight convolution block to replace the two modules in the original model for automatically classifying OCT retinal images. Image pre-processing, dataset division and classification using the model algorithm are the steps taken to achieve the automatic classification of the entire OCT retina. First, image cropping is performed on the collected OCT image, the blank area of the OCT image is cropped, the marginal blank area is filled and bilateral filter denoising and other pre-processing methods are used to overcome the interference of image background noise on the classification accuracy. Then, the pre-processed image is divided into three sets: training, validation, and test sets. Afterwards, the OCT images from the training set are trained using the proposed multi-channel lightweight deep neural network GM-OCTnet model algorithm. Following the test, the well-trained model is used to classify unclassified retinal images automatically. In addition, the results of this work on the automatic classification of OCT retinal images are validated by comparing the proposed model with three traditional lightweight models on the OCT data set, and different data sets are used to further validate the algorithm’s performance.Results and Discussions Different pre-processing methods were used to process the OCT images after evaluating the quality of two different data sets (Figs. 4 and 5). The experimental results show that when the number of groups is 4, the proposed multi-channel OCT automatic retina classification network achieves an average accuracy of 96.1%, which is 2.6% higher than that of the original model GhostNet in the automatic classification of OCT retina images. Its file size is 2.64×10 6smaller than that of MobileNetV3. The training and verification accuracies of the GM-OCTnet model when the grouping g=4 increase gradually with the increase of the training period and tend to stabilise, based on the relationship between the verification loss rate and the verification accuracy rate and the training loss rate and the training accuracy rate curve. When comparing the 50 training processes of different models, the proposed model is found to exhibit a higher accuracy rate than other models when the number of groups is equal to 4 and prioritises reaching the best value (Fig. 6). Overall, the model algorithm proposed in this paper has achieved high accuracy in the automatic classification of OCT retinal images. In addition, when the experimental results of two different datasets are compared, it is discovered that the automatic classification of datasets 1 and 2 achieved high classification accuracy using this algorithm (Tables 1 and 2). Conclusions This study proposes a multi-channel, multi-scale lightweight network for automatically classifying OCT retinal images. The effect of the lightweight neural network GM-OCTnet based on the OCT image datasets in classifying and diagnosing the four types of ophthalmic conditions, i.e. choroidal neovascular disease(CNV), diabetic macular edema(DME), drusen and normal patients, were tested and evaluated. Two different datasets are used to further validate the performance of the algorithm proposed in this work. To validate the effectiveness of the GM-OCTnet model for OCT image classification, accuracy, parameter amount, calculation amount and weight file size are used as evaluation criteria. It is found the proposed OCT classification model has improved classification accuracy through experimental results. When used in the clinic, it can improve professional ophthalmologists’ diagnosis efficiency for patients with ophthalmic diseases and also reduce missed diagnosis and misdiagnosis of patients.

Objective Given the increased prevalence of digestive diseases in recent years, the endoscope has been widely used for abdominal diagnoses, including those related to the stomach and intestines. Researchers are working to develop more effective and less invasive techniques for patients to benefit from endoscopy. A large field-of-view (FOV) and high resolution will reduce examination time and improve evaluation accuracy. Moreover, a compact endoscope structure is critical for minimising patient discomfort. In conventional wide-field camera lenses, a large panoramic scene needs to be focused onto an image sensor plane, to reduce the field curvature caused by the strong mismatch between the focal planes. The concentric lens consists of four refractive surfaces, and the centres of curvature of each refractive surface coincide at one point. Therefore, off-axis aberration does not exist. Only spherical and axial chromatic aberrations need to be corrected. Therefore, this structure can be applied to optical systems with miniaturisation, high image quality, and a large FOV; however, the image surface formed by the concentric system is curved. In this study, we correct the curvature of the field in the concentric sphere system by designing an annularly stitched aspheric surface to achieve flat-field imaging with a large FOV.Methods In this study, an optical system with full FOV is regarded as a combination of multiple single- or small-FOV sub-system units, then the sub-field units are solved separately, and the formation of a complete complex surface is optimised to realize the construction of a complete optical system. First, the initial concentric structure is solved with well-corrected spherical and chromatic aberration. Then, based on the FOV, an annularly stitched surface is constructed by dividing the surface into rings and calculating the initial structure parameters of each zone based on the flat-field conditions. The Q-type aspheric surface characterises different annuli to ensure imaging quality while obtaining good splicing results. Simultaneously, the continuity constraint condition of the annularly stitched aspheric surface is derived. Finally, a complete surface is optimized to realize the construction of a complete electronic endoscope.Results and Discussions The deviation of normal and sag between adjacent rings has been reduced to less than one-tenth of the test wavelength (typically test wavelength 632.8 nm) through optimisation. These rings are then fused after the optimisation. The system diagram is shown in Fig.10. Compared with the modulation transfer function (MTF) curve of the initial structure in Fig. 3, the MTF of the system after optimisation is more than 0.3 at the spatial frequency of 72 lp/mm (Fig.11). Thus, the curvature of the full FOV is reduced from 0.5 mm in the initial structure to within 0.1 mm [Fig.12(a)], the imaging requirements of electronic endoscope objectives are met. To validate the design results’ manufacturability, a Monte Carlo simulation analysis was performed 200 times within the tolerance range (Fig.14). Consequently, in the full FOV, considering mass production and assembly, a probability that an optical system with an average diffraction MTF greater than 0.3 at 72 lp/mm frequency can be obtained is more than 90%.Conclusions Based on the concentric structure, multiple rings are superimposed on the last surface to obtain different optical powers to generate the initial surface shape of the splicing surface of the rings. The surface shapes of the multiple rings are fused to generate a complete continuous surface after the continuous conditions are optimized. In the design, the Q-type aspheric surface is used to characterise different ring zones to ensure imaging quality. An electronic endoscope objective lens operating in the visible band is designed using this method. The objective comprises only four refractive surfaces, with a total system length of 2.81 mm and FOV of 90°. The field curvature of the system is less than 0.1 mm, the distortion is within 20%, the MTF reaches 0.3 at 72 lp/mm, and the relative illuminance of the full FOV is greater than 0.5, which meets the imaging requirements of electronic endoscope objectives. The system uses the imaging advantages of the concentric objective lens with a large FOV and small volume. The annularly stitched aspheric surface is used to correct the curvature of the field caused by the spherical lens. Compared with the traditional structure, our electronic endoscope objective lens is more compact and readily manufacturable.

Objective In microplastic surgery, hyaluronic acid is injected into the dermis layer under the wrinkle depression to achieve the wrinkle removal effect. However, the percutaneous needle can puncture facial arteries, causing the penetration of hyaluronic acid into the blood vessels to form emboli and induce vascular embolism, resulting in local tissue ischaemia, blindness, and even stroke. The visualisation of human facial blood vessels can solve this problem. Photoacoustic imaging is a mesoscopic imaging method with high specificity and contrast based on optical absorption differences and ultrasound information carriers. This method combines the advantages of high resolution of optical imaging and large penetration depth of ultrasonic imaging. It has been widely studied in the biomedical imaging field. As an important branch of photoacoustic imaging, photoacoustic microscopy can obtain high-resolution and high-contrast images of blood vessels in the dermis layer of the human skin in a noninvasive and label-free manner. Therefore, a photoacoustic microscopy was proposed to navigate injection-based microplastic surgeries.Methods The needle inserted at a fixed angle was imaged using a photoacoustic microscopic probe to obtain the injection point of the needle. Then, the three-dimensional (3D) vascular imaging of the target area was performed. Based on the image fusion and quantitative evaluation, it can be assessed whether the needle will puncture the facial arteries, thereby reducing the risk of surgery. In this study, the feasibility of this method is confirmed using leaf vein imaging and in vivo mouse-ear imaging. Image reconstructions were performed using a user-defined programme, LABVIEW (2019, National Instruments, USA). The three-dimensional images and image fusion were obtained using functions provided by ImageJ (National Institutes of Health, USA). The user-defined algorithm implemented in MATLAB (R2019b, MathWorks, USA) was used to calculate the number of pixels in the intersection area of the image fusion.Results and Discussions Leaf veins were used to simulate the blood vessels of the dermis layer. The diameter of the leaf vein trunk was approximately 300--500 μm (for simulating facial arteries) and that of leaf vein branches was 100 μm is 35 and 31, respectively. The number of pixels intersecting the capillaries (positions 2 and 5) is 8 and 5, respectively. The number of pixels in positions 3 and 6 without the blood vessels is 0 (Fig. 4).Conclusions The experimental results of leaf veins show that photoacoustic microscopy can predict the relative position of the needle, simulate the blood vessels, and navigate the needle into a safe area. Results of the in vivo mouse-ear experiment show that photoacoustic microscopy can quantitatively determine the type of blood vessel punctured by the needle based on the number of pixels in the intersection area. Therefore, this study is expected to realize the preoperative navigation of injection-based microplastic surgeries and shows good application prospects for improving the safety of injection-based microplastic surgeries. However, some aspects still require improvement. The wavelength of the laser employed herein is 532 nm. Naturally, blood vessels show high absorption at this wavelength; however, the imaging depth is limited owing to the strong scattering of light by biological tissues. Furthermore, high wavelengths of the laser will be used in the future, e.g., 1064 nm, to achieve high imaging depth. Currently, only the upper surface information of the needle can be extracted owing to the limitation by the optical excitation mode of the system; moreover, post-processing algorithms are needed to determine whether the needle touches the blood vessel. In the next step, a complete needle can be simulated using the real size of the needle to improve the accuracy of the experiment. Additionally, there is a certain degree of blindness in the selection of the injection position and the probe must be moved repeatedly. The large imaging view and high imaging speed will considerably improve the detection efficiency. Moreover, owing to the limitation of the imaging speed, the proposed system can only realize preoperative navigation, not intraoperative navigation. Further, this system cannot monitor the process of needle entering the sample in real time. Subsequent work will focus on the aforementioned issues to improve the system.

Objective Acceptor-sensitized 3-cube fluorescence resonance energy transfer (FRET) imaging (also termed E-FRET imaging) is a popular FRET quantification method in living cells that uses fluorescence intensity. We recently developed a measurement of calibration factors (termed as mTA-G method) that eliminates the influence of the emission transmission characteristics of the instrument used on quantitative E-FRET measurement, significantly increasing the success rate and accuracy of quantitative E-FRET measurement in living cells. Because of its inherent ability to resolve the excitation-emission spectra of donor and acceptor, as well as donor-acceptor sensitization, spectral unmixing of simultaneous excitation and emission spectra (mExEm-spFRET) has been used for quantitative FRET measurement without the need for additional reference for correcting the excitation crosstalk. We evaluated the two methods’ robustness by implementing them on a self-assembled quantitative FRET measurement system with cells expressing different constructs.Methods The research methods of this paper are mainly divided into four sections: Cell culture and plasmids transfection, predetermining spectral crosstalk and spectral fingerprints, measuring calibration factors and system parameters, superior robustness of mExEm-spFRET to E-FRET method. First, MCF-7 cells were cultured in 6-well plates. For transfection, cells were separately transfected with four different FRET plasmids using transfection reagent. Then, living MCF-7 cells separately expressing YFP (Y) and CFP (C) were used to predetermine the spectral crosstalk coefficients (a, b, c and d) and spectral fingerprints (SD, SA, and SS) were shown in Fig.1 and Fig.2. Next, calibration factors (G and γ) were measured using cells expressing C4Y, C10Y, C40Y, and C80Y (Fig.3). The cells expressing C4Y were used to measure system parameters (fSC and rK) (Fig.4). Finally, to evaluate the robustness of mExEm-spFRET and E-FRET methods, we performed quantitative mExEm-spFRET and E-FRET measurements respectively for the same cells separately expressing four kinds of plasmids under different signal-to-noise ratios (RSN) on different days (Fig. 5 and Table 3).Results and Discussion The E and RC values of different FRET plasmid in the cells in Fig. 3 measured by mExEm-spFRET and E-FRET method were shown in Table 1, respectively. For cells 1 and 2, the E and RC values measured by both methods were consistent with the reported E values and the expected RC values. Still, the E values measured by E-FRET were generally larger than those calculated by the mExEm-spFRET method. These results indicate that both methods are applicable for live-cell FRET measurement. Table 2 shows different constructs’ statistical E and RC values in living MCF-7 cells under different RSN. For the cells under RSN>3, the two methods obtained consistent FRET efficiency (E) values, but E-FRET obtained smaller donor/acceptor concentration ratio(RC) values than the expected for individual constructs; for the cells under RSNRC values, but the deviation of individual plasmid E values obtained by E-FRET was slightly larger. These results further demonstrate E-FRET has slightly less robustness than the mExEm-spFRET method, especially for the cells under a low RSN. We repeated the above measurements on our system on March 10 th and obtained consistent results with FRET results measured on December 12 by mExEm-spFRET (Table 3). But the RC values of C80Y obtained by E-FRET were inconsistent with expected values. These results show the superior robustness of mExEm-spFRET to E-FRET method especially for the cells with low E (ERSN, resulting in the inaccurate results measured by the E-FRET method. Because of the excellent robustness of mExEm-spFRET, just as described above, the mExEm-spFRET method still obtained accurate results for the C80Y construct in the cells with a low RSN. Conclusions In this report, we evaluated the robustness of both E-FRET and mExEm-spFRET methods by implementing E-FRET and mExEm-spFRET measurements, respectively, with two excitation wavelengths using the same cells expressing different constructs under different RSN. For the cells under RSN>3, the two methods obtained consistent FRET efficiency (E) values, but E-FRET obtained smaller RC values than the expected for individual constructs; for the cells under RSNRC values, but the deviation of individual plasmid E values obtained by E-FRET was slightly larger. E-FRET and mExEm-spFRET methods are very applicable for live-cell FRET measurement and the superior robustness of mExEm-spFRET to E-FRET method, especially for the cells with low RSN and E (RSNE

Objective Optical coherence tomography (OCT) has been widely used in clinical medicine, materials science, tissue engineering, among other fields due to its advantages of non-destructive, non-contact, high speed, and high resolution. In the traditional OCT system, which is based on Gaussian beam illumination, the lateral resolution is determined by the size of the focused spot of the Gaussian beam. However, the smaller the focused spot, the shorter the depth of focus, and the rapid drop of the lateral resolution outside the depth of the focus area. Therefore, improving the depth of the focus, while maintaining a high lateral resolution is one of the important problems to be solved in a high-resolution OCT system. Bessel beam is used to extend the depth of the focus of the OCT system because of its non-diffracting property. Bessel beams can be generated by the optimal solution of the first-order circular Dammann grating (CDG), and the depth of the focus can be extended effectively, while the diffraction efficiency can reach 81%. However, in the existing CDG design, the splitting effect of the first-order diffraction ring will lead to a zero-energy dent in the axial direction of the central spot of the Bessel beam, resulting in a short depth of focus. To solve this problem, this paper proposes a depth of focus extension method, which eliminates the axial energy dent of Bessel beam generated by CDG. Moreover, it can effectively reduce the splitting effect of the first-order diffraction ring, improve the uniformity of axial intensity distribution within the depth of the focus range of Bessel beam, and realize the depth of the focus extension of the OCT system.Methods In this paper, by optimizing the radius of the central circle of the CDG and the ratio of the binary phase in a single period, we design a CDG for generating Bessel beams that eliminate the energy dent, and apply it to the OCT system, which effectively extends the depth of the focus of the system. Based on the principle of the CDG diffraction, the CDG parameters that meet the requirement of eliminating the first-order diffraction ring splitting are derived and the optimal CDG design is obtained. We use the software simulation to prove the feasibility of the design. Based on our simulation, we set up a swept-source OCT system with the CDG. The system is used to imaging the samples of polystyrene microspheres embedded in agarose gel and multilayer white tape to verify the effectiveness of the focal depth extension and the imaging capability of the system.Results and Discussions The energy dent in the depth of focus of the Bessel beam generated by CDG diffraction is eliminated, and the axial intensity uniformity is improved [Fig. 8 (c), (d)]. Based on the CDG design, we built a swept-source OCT system, the axial resolution in the air is 8.24 μm (Fig. 11). Imaging results of the polystyrene microspheres measured by the system show that the system can achieve a lateral resolution of 3.9 μm over the depth of the focus range of 1.8 mm (Fig. 12). Additionally, the system is used to image human nails and multilayer white tape samples. In OCT imaging of human nails, the boundary between the cuticle and nail can be clearly distinguished, and the nail extending under the skin can be observed [Fig. 13 (a)]. Furthermore, the optical thickness of the multilayer white tape sample is about 2 mm. The layered structure of the multilayer white tape can be clearly distinguished in the OCT image, and the air layer between the white tape and the upper surface of the glass slide can be observed [Fig. 13 (b)].Conclusions Based on the diffraction principle of CDG, the energy splitting effect of the first-order diffraction ring of the CDG is reduced by optimizing the central circle radius of the CDG and the ratio of the binary phase in a single period. On the premise of maintaining a higher first-order diffraction efficiency, the axial energy dent of Bessel beam generated by the CDG is eliminated, and the depth of the focus is effectively extended. A swept-source OCT system based on Bessel beam illumination is built by the optimized CDG. By measuring polystyrene microspheres embedded in the agarose gel, it is proved that the system can achieve a lateral resolution better than 3.9 μm over the depth of the focus range of 1.8 mm, which is consistent with the calculated theoretical result of the depth of the focus and lateral resolution. By using the system, clear tomographic images of human nails, white tape, and other samples were obtained, which verified the imaging ability of the system.

Objective Early-stage screening and treatment of mucosal tissue lesions are particularly important for mucosal cancer prevention. Since most mucosal lesions originate from the superficial epithelium, that is sub-diffusive regime, where the diffusion approximation theory is no longer applicable. In the sub-diffusive regime, the second-order phase function parameter γ has a great effect on the sub-diffusive reflectance, in addition to the absorption coefficient μa and reduced scattering coefficient μ's. Therefore, traditional diffuse reflectance spectroscopy (DRS) technique has some deficiencies in the early detection of mucosal lesions. Sub-diffusive reflectance spectroscopy (sDRS) technique can collect the light at short source-detector separations, which experiences fewer scattering interactions and carries more information about the microstructure of the tissue. Meanwhile, sDRS can achieve quantitative and multi-parameters detection, making it more suitable for mucosal tissue screening. In order to determine the optical properties of mucosal tissue, a spatially resolved reflectance in sub-diffusive regime measurement system was designed and digital lock-in detection technique was adopted to improve measurement speed and suppress random noise.Methods In this study, the sDRS system is composed of light source module, hand-held optical fiber probe, data acquisition module, central control module, signal processing and human-computer interaction module. By collecting the reflection light of multi-wavelengths (520, 650, 785 and 830 nm) and multi-source-detector separations (220, 440, 660, 880 and 1100 μm), the system realizes the detection of spatially resolved sub-diffusive reflectance spectrum. In this system, digital lock-in detection technique of square-wave modulation is adopted by which the four wavelength light sources are excited simultaneously, and the five detectors are used to detect the reflected light parallelly. In addition, the system noise and the ambient light interference can be suppressed, which is extremely meaningful for detecting weak light. In order to demonstrate the feasibility of the system, a series of experiments are conducted to assess the system’s performances in terms of stability, linearity, ambient light suppression, and anti-crosstalk among multi-frequency channels. To further verify the effectiveness of the proposed system, turbid phantom experiments are carried out. Herein India ink and polystyrene microspheres are used to simulate the absorption and scattering properties of mucosal tissue, respectively. A modified forward Monte Carlo numerical model based on optical fiber probe geometry and Gegenbauer-kernel phase function and 3D lookup-table algorithm are used to predict the three optical parameters (μa, μ's, γ) simultaneously and quantitatively.Results and Discussions The assessment results show that the fluctuation ratio of the system is less than 1.5% (Fig. 2); the crosstalk ratio among multi-frequency channels is less than 3% (Fig. 3). At different intensities of ambient light, all the voltage amplitudes obtained based on the digital lock-in detection technique are very low and almost unchanged (Fig. 4). When the intensity of the light source increases with a specific step, the correlation coefficients of the corresponding detection values obtained by linear fitting are all close to 1 (Fig. 5 and Table 1). Turbid phantom experiment results show that the predicted values and true values of optical parameters demonstrate satisfactory consistency (Fig. 6 and Table 3), under the condition that the numerical simulation noise cannot exactly match the experimental noise. These experimental results prove the feasibility and effectiveness of the proposed system and its potential application in mucosal lesion recognition.Conclusions In this paper, towards practical application, a spatially resolved reflectance in sub-diffusive regime measurement system combined with digital lock-in detection technique was designed, which has the advantages of non-invasiveness, portability and speediness. A series of preliminary system evaluation experiments and turbid phantom experiments verify that the system possesses good stability, linearity, anti-frequency crosstalk ability as well as strong anti-ambient interference ability, and can effectively predict the three optical parameters simultaneously, indicating the feasibility and effectiveness of the proposed system. In the future work, we will further study the potential application of sDRS in the detection of mucosal lesions in vivo.

Objective As a new molecular imaging modality, Cherenkov-excited luminescence scanned imaging (CELSI) has demonstrated a great potential, especially in radiation therapy diagnostics. However, it can not provide in-depth information about molecular probes. Therefore, it is necessary to develop tomographic algorithms for CELSI. However, reconstructing spatial distributions of luminescent sources from boundary measurements is a typical ill-posed problem. Our previous work has demonstrated the feasibility and effectiveness of using Tikhonov and sparse regularizations for CELSI reconstruction. However, the quality of reconstructed images will degrade when the luminescent source is located at deep positions. The objective of this study is to develop a reconstruction algorithm for CELSI to improve the quality of reconstructed images.Methods A two-stage reconstruction algorithm is developed in this study. First, low-quality images were reconstructed on the basis of Tikhonov regularization at the first iteration. Then, the resultant images were input into a revised Unet network, which had an encoder-decoder architecture. The encoder comprised four convolution blocks and four downsampling layers. Every convolution block comprised two convolution layers, and each convolution had a kernel size of 3×3 with a stride of 1. The downsampling layer had a convolution of size 3×3 with a stride of 2. In upsampling networks, the transposed convolution with a kernel of 3×3 and stride of 2 was used to replace direct interpolation used in the standard Unet. Here, we used leaky rectified linear units as the activation function to intensify the network in each convolutional layer. The batch normalization technique was used to accelerate learning. In addition, skip connection was applied to connect the first and last layers. The feasibility of the algorithm was evaluated through numerical simulations. Training and test datasets were generated using an open-source software, NIRFAST. For comparison, our algorithm was compared with Tikhonov regularization, approximate message passing (AMP), and graph-total variation (Graph-TV).Results and Discussions First, a single circular target with 8 mm diameter was placed within the phantom with varying depths ranging from 10 mm to 50 mm. Although the four algorithms could reconstruct the distribution of targets, severe artifacts were found in images reconstructed by Tikhonov regularization, and the shapes of reconstructed targets were changed for AMP and Graph-TV (Fig.5). Additionally, the quality of reconstructed images by Tikhonov regularization, AMP, and Graph-TV degraded as the depth increased. By contrast, our results reveal that the quantitative accuracy of recovered distributions of luminescence sources could be significantly improved by the proposed algorithm, which achieved the best image quality with a high peak signal-to-noise ratio (>28 dB) and structural similarity (>0.92). Furthermore, experiments with two luminescent sources were conducted to evaluate the algorithm’s performance. When the edge-to-edge distance of two luminescent sources was 3 mm (Fig.13). The computational efficiency for the four algorithms is also demonstrated. The three traditional reconstruction algorithms require >45 s, whereas our algorithm requires ~11 s (Table 1).Conclusions A tomographic reconstruction algorithm for CELSI is proposed to reconstruct distributions of luminescence sources based on a trained Unet neural network. Numerical simulations are used to evaluate the performance of our proposed algorithm. Our results reveal that both the image quality and quantitative accuracy of reconstructed fluorescence yield can be improved using the proposed algorithm compared with the conventional Tikhonov, sparse, and total variation regularizations. The proposed algorithm can reconstruct the distributions of luminescent sources when the depth is

Objective Fluorescence emission difference (FED) microscopy is a versatile super-resolution microscopy flexible for all types of fluorescent dyes. However, the limited imaging speed is the main drawback that hinders the application of FED, owing to the double imaging process of positive confocal image using a solid spot scan and negative confocal image using a negative spot scan. Parallel fluorescence microscopy can overcome this limitation owing to its ability to simultaneously capture positive and negative confocal images. However, the complexity of this method’s system will increase instability and difficulties in daily maintenance, which also considerably restricts the popularization of the method. In this study, a new imaging method using a spatial light modulator (SLM) named common-path parallel FED (cpFED) microscopy was proposed. Compared with the traditional parallel FED microscopy, the proposed method that uses SLM and common path modulation maintains the advantage of doubling the imaging speed while overcoming the impact of instabilities introduced by different devices in noncommon-path parallel systems and simplifies the light path.Methods A property of SLM is that only linear polarized light can be modulated in a fixed direction, which is the major property of common-path parallel FED microscopy. Using the polarization rotation realized by passing forth and back through a quarter-wave plate, SLM can modulate the s and p polarization components of the emitted light (Fig. 1). Using two-phase grayscale patterns, vortex and tilt-grating modulation patterns, to simultaneously modulate the horizontal and vertical polarization components of the incident laser beam on a single SLM, a staggering Gaussian solid spot and a hollow spot are generated to form the final convergent light field at the focus plane. The solid and hollow spots scan the sample simultaneously, and the fluorescence signal excited by the two spots is measured using two detectors, which will introduce a fixed transverse displacement between two images. Translating the positive confocal image to align with the negative confocal image and combining with the FED algorithm, the fast super-resolution imaging of the sample is realized. Experimental results show that the proposed method exhibits good ultradiffraction-limit imaging capabilities and high imaging speed and the resolution can be increased by approximately two times compared with traditional confocal imaging.Results and Discussions To test the performance of cpFED, the experimental results of 200 nm and 100 nm fluorescent beads were presented herein. The 200 nm fluorescent beads were used to adjust the system and demonstrate the translation effect between the positive and negative confocal images because of its’ high fluorescent quantum efficiency (Fig. 2). The 100 nm fluorescent beads were used to measure and determine the optimum resolution performance of cpFED (Fig. 3). The full width at half maximum of a single bead plotted in Fig. 3(c) reveals that the resolution of cpFED in our system can reach up to 133 nm, indicating that the resolution of cpFED can be increased by approximately two times compared with traditional confocal imaging. Furthermore, a vimentin sample was used to verify the biological application of cpFED. The insects depicted in Fig. 4(a1), (b1), (a2), and (b2) show that the resolution and contrast in cpFED can be significantly promoted, while the noise in cpFED is considerably lower than that in traditional confocal imaging.Conclusions Using SLM, cpFED can realize a small translation between solid and donut spots in a common path and simultaneously capture positive and negative confocal images, thus overcoming the imaging speed limit and promoting the biological application of FED. Compared with pFED, the proposed cpFED simplifies the system structure, reduces the adjustment complexity, and improves the robustness of the system because of the SLM flexibility. Experimental results demonstrate that cpFED achieves a resolution improvement of two times that of traditional confocal imaging while achieving double the imaging speed.

Objective In photoacoustic tomography, considering the size of ultrasonic transducers, especially for ones with large active surfaces, the traditional model-based (MB) method sums up the forward model matrix of each discrete point from the active surface to build this matrix. Although this traditional method has greater accuracy than the delay-and-sum method and back-projection method, with an increase in the number of discrete points from the active surface of transducer, the computing time and memory consumption will be more. Here, we present a new MB photoacoustic reconstruction algorithm based on the concept of virtual parallel projection. This model is suitable for photoacoustic tomography systems employing flat or cylindrical focused transducers with large active surfaces. This reconstruction algorithm directly establishes a virtual parallel-projection model matrix to replace the sum of the model matrices of the discrete points of the surface. The proposed method has an image performance similar to that of the traditional MB reconstruction method with discretized surface elements but considerably lower time consumption and storage requirements in the reconstruction process. We hope that this high-efficiency, high-accuracy method can provide a valuable reference and guidance for the research on MB photoacoustic reconstruction algorithms for use in real-time photoacoustic tomography.Methods A photoacoustic reconstruction algorithm based on a virtual parallel-projection model is introduced to solve the problem caused by transducers with large active surfaces. When the distance between the image center and transducer satisfies the virtual parallel-projection condition (Eq. 6), the back-projection profile of each discrete point on the active surface in the reconstruction area can be approximated as a straight line parallel to the transducer (Fig.3). Then, a virtual parallel-projection model matrix can be directly built to replace the sum of the model matrices based on all discrete points on the surface. This step helps avoid the repeated matrix calculations of each discrete point and can reduce the time and memory requirements. The image performance of the proposed method was first demonstrated by numerical simulation using microspheres with a radius of 200 μm. We compared the photoacoustic images reconstructed by three methods, namely, the traditional model-based (MB) method, MB method with discrete surface elements (MB-SE), and proposed method based on virtual parallel-projection (MB-VP). The computing time and memory consumption of MB-SE and MB-VP methods were quantitatively calculated to show the high efficiency of the proposed method. Then, the phantom experiment was implemented using a self-built photoacoustic imaging system to verify the reconstructed accuracy of the MB-VP method (Fig.1). This agar phantom consisted of some polyethylene microspheres of diameter 200 μm. These microspheres were approximately embedded on the same plane in the phantom. Finally, to assess the feasibility of the MB-VP method for in vivo imaging, animal experiments were performed on the thoracic cavity region of a four-week-old KM mouse (~18.4 g).Results and Discussions The reconstruction results of the proposed MB-VP method show high image quality and high reconstruction accuracy, comparable to those of the MB-SE method (Fig.4). However, the MB-SE method obtains desirable reconstruction results at the expense of computing time and memory consumption by increasing the number of discrete points on the active surface of the transducer (Table 2). When the active surface of the transducer is discretized into 15 points for the MB-SE method, the calculation time exceeds 10 min, which is approximately 20 times that of the proposed MB-VP method. In contrast, the MB-VP method provides higher quality and better spatial resolution in the reconstructed image with significantly lower reconstruction time and memory consumption (Fig.6). The phantom experiment results, which are consistent with the numerical simulation results, demonstrate that both MB-VP and MB-SE methods can effectively suppress image artifacts and obtain high-fidelity reconstructed images (Fig.7 and Table 3). The animal experiment results show that the result of the MB method suffers from artifacts and distortions, especially in the imaging of blood vessels at the position of the mouse epidermis far away from the image center; in contrast, the shapes of these blood vessels are accurately recovered by the MB-SE and MB-VP methods (Fig.8).Conclusions In this work, a novel MB reconstruction algorithm based on the concept of virtual parallel-projection is developed to achieve high-efficiency MB reconstructions for photoacoustic tomography employing flat or cylindrical focused transducers with large active surfaces. By quickly and accurately building the forward model matrix based on the virtual parallel-projection condition, the proposed method can break the trade-off between reconstructed accuracy and computing consumption, which limits the applications of the traditional MB reconstruction methods. The results of numerical simulations, phantom experiments, and in vivo experiments demonstrate that the execution time and memory space required to reconstruct the initial pressure image are considerably reduced by the proposed method without sacrificing the quality of the reconstructed images. In other words, the MB-VP and MB-SE methods can obtain similar reconstructed images with higher quality and higher fidelity than the MB method, while the computational cost of the MB-VP method similar to that of the MB method, that is, it is much lower than that of the MB-SE method. The computational efficiency of the proposed method can be further improved through the parallel computation approach based on graphics processing unit acceleration to meet the requirements of real-time photoacoustic tomography.

Objective Optical coherence tomography (OCT) has become the de facto gold standard of diagnosis in ophthalmology. In recent years, with the rapid improvement in imaging speed and the wide adoption of OCT angiography (OCTA), a large amount of retinal OCT B-Scan can be generated in one clinical scan. Automatic and effective retinal tissue segmentation is required to realize this trend. Conventional segmentation algorithms based on path searching are time consuming and error prone when dealing with morbid retinas. In such cases, neural-network (NN)-based methods such as U-Net and ReLayNet are promising approaches. These NN-based methods differ in complexity and performance. For the desktop computer in the current mainstream OCT equipment, an NN with moderate parameter sets and high performance is highly desirable. In this study, we demonstrate a novel end-to-end segmentation method for retina images, named multiple-scale inpainting convolutional NN (MsiNet) for retinal layer segmentation. MsiNet is based on human visual characteristics and can be implemented on a desktop computer with high performance. The framework was validated on two retina image datasets with comparisons against U-Net and ReLayNet, which are well established in retinal OCT image segmentation. MsiNet showed better performance than the other two methods in terms of both retinal layer segmentation accuracy and morbid tissue segmentation, with a moderate parameter set size suitable for desktop computers.Methods MsiNet is based on semantic segmentation with encoder-decoder architecture and convolutional NNs (CNNs). We regarded retinal layers as different categories and predicted a pixel’s probability to different categories. The human visual system usually detects objects in two steps: first, it tends to obtain semantic (outline, location, etc.) information; second, it is used to focusing on details. Inspired by this fact, we employed a small-scale network as a decoder to refine semantic information and then used inpainting networks to extract spatial structures from high-resolution feature maps for inpainting low-resolution results. Thus, semantic and detailed information in different stages could be refined directly with less redundancy. To fit MsiNet into the limited computation resource, we reduced the number of parameters and floating-point operations using new structures: interlaced residual unit (IRU) and biased fusion unit (BFU). We also adopted a single-stage decoder instead of a traditional decoder and improved the segmentation results stage by stage. Further, we designed a joint weighting method for some special pixels to intensify punishment. Multiple losses were provided in different resolution stages for obtaining different resolution results. Compared with two well-established NN-based methods, the segmentation accuracy on edges was significantly improved.Results and Discussions MsiNet was tested on two retinal OCT datasets: the SD-OCT dataset and a dataset provided by a third-party company (TOWARD π Medical Technology). We compared MsiNet with two well-established NN-based methods: U-Net and RaLayNet. First, using the GSE(generalized semantic boundary) weighting method, the accuracy of edge and disease tissue prediction of MsiNet was better than those of U-Net and RaLayNet (Table 1). Second, by comparing the outputs of different stages in Fig. 6, we confirmed that a high-level decoder significantly improves the accuracy of low-level outputs. Third, MsiNet outperformed U-Net and RaLayNet in terms of both retinal layer and morbid tissue segmentation accuracy, with a moderate parameter set size suitable for desktop computers. The results of the three methods are demonstrated in Fig.7 and Table 1.Conclusions Based on human visual characteristics, we propose MsiNet for retinal tissue segmentation. MsiNet replaces the traditional decoder that merges different-resolution feature maps with a single-stage decoder in low resolution, and an inpainting network is designed to rectify segmentation errors and add structural information to phased results. An extended GSE mask is applied to the loss function to adjust the weights of edge pixels. Because of the clear semantic information, the parameter set size is significantly reduced. Experiments show that MsiNet outperforms U-Net and ReLayNet in terms of both layer segmentation and morbid tissue segmentation, mainly due to the improvement in edge point classification.

Significance Recently, neuroscience has attracted great attention around the world. To prompt the study of neuroscience, a lot of countries have launched brain projects, in which the development of advanced neural techniques is regarded as the driving force. Optical techniques own the advantages of being less-invasive and high spatial resolution, etc, promising for neural activity recording and manipulation. Compared to traditional electrode stimulation methods, optical stimulation based on optogenetics could selectively excite or inhibit specific neural ensembles, benefiting from the introduction of gene engineering. So far, a variety of opsins have been developed for the activation or inhibition of neural activity. On the other hand, to achieve selective manipulation at single-neuron resolution, the techniques for two-photon optogenetics are emerging. Here, we review various strategies for illumination in two-photon optogenetics. We summarize their technical principles, and discuss their advantages and disadvantages.Progress Illumination strategies in optogenetics can be classified as conventional illumination strategies based on single-photon absorption and high-spatial-resolution illumination strategies based on two-photon absorption.In the early days of optogenetics, the wide-field illumination strategy based on single-photon absorption was used to manipulate neurons with opsins. Due to the scattering and absorption of biological tissues, the power of illumination light decreases significantly with the increase of penetration depth in wide-field illumination strategy. For neuron manipulation in deep tissues, fiber-coupled illumination is performed, in which the excitation light is guided through the fiber to the targeted depth. However, specific manipulation of neural activity at single-neuron resolutions is not achieved in neither wide-field illumination nor fiber-coupled illumination, due to the fact that all neurons with opsins in the illumination region would be excited.For specific manipulation of neural activity at single-neuron resolution or sub-neuron resolution (such as a dendrite or a dendritic spine), the two-photon illumination strategy has to be adopted, which ensures high spatial resolution in three-dimensional (3D) space. Besides, the longer wavelength in two-photon excitation is more robust to scattering and leads to a deeper penetration depth than that of the conventional illumination strategies.In general, the two-photon illumination strategies can be classified as serial scanning illumination and parallel illumination based on phase modulation. In the former, a single focus is steered to perform spiral scanning on a neuron to open enough ion channels for neuron excitation before being switched to another neuron (Fig. 1). Or, serial scanning with soma-patterned illumination can be employed (Fig. 2). However, the temporal resolution in these methods is low, which makes it only compatible with opsins of slow turn-off time. Besides, parallel illumination can be achieved based on phase modulation (Fig. 3), in which the phase can be calculated by the generalized phase contrast (GPC) method and the computer generated holography (CGH) method. The phase modulation plane of GPC is the conjugate plane of the focal plane, while that of CGH is the conjugate plane of the Fourier plane. The GPC method has good uniformity of excitation patterns but is of a poor energy efficiency. Based on the theory of CGH, two illumination schemes have been developed, i.e. the multi-foci generation combined with the spiral scanning strategy, and the multiple extended-pattern generation strategy. The former has a high energy efficiency and can realize the excitation of 3D distributed neurons, but it is of poor temporal resolution and only works with opsins of slow turn-off response time. The latter can directly generate a multiple expanded-pattern and excites multiple neurons simultaneously. Combined with the temporal focusing technology, this method has high temporal resolution and high axial resolution, however, its energy efficiency is low. At the same time, we summarize the commonly used CGH algorithms for parallel illumination based on phase modulation, which contain superposition algorithm, Gerchberg-Saxton (GS) algorithm, non-convex optimization (NOVO) algorithm, and DeepCGH algorithm. The diagrams of different algorithms are presented (Fig. 4). The basic ideas, advantages, and disadvantages of these algorithms are briefly pointed out.Conclusion and Prospect Conventional neural manipulation in vivo relies on single-photon illumination, which is not good for specific excitation of neural ensembles at high spatial resolution. To this end, several techniques of two-photon optogenetics have been proposed, and have achieved in vivo neural manipulation at high-spatial-resolution. We summarize the development of two-photon illumination strategies, and compare their advantages and disadvantages. Then we discuss the potential issues in the practical employment of two-photon optogenetics, such as excitation precision and field-of-view. We expect that, the all-optical physiology, in which two-photon imaging and two-photon optogenetics are combined, is promising in neuroscience, benefiting from the simultaneous monitoring and manipulating of neural circuits in vivo.

Significance With the growing demand for health care and the development of medical examinations, more accurate and minimally invasive diagnosis and treatment technologies have received extensive global attention. Currently, a rapid and effective intraoperative diagnostic method is still lacking for major diseases in clinical practice. Traditional medical imaging modalities, such as magnetic resonance imaging, computed tomography, ultrasound imaging, positron emission tomography, and single-photon emission computed tomography, are commonly used to present the global anatomical structure or functional information of human tissue, but their resolution is too low to show fine structures. Histopathological examination is the gold standard for malignant tumors and other diseases, which detect pathological changes in cells on a microscopic scale with the best accuracy. However, the process is complex and time-consuming and depends on the distribution of biopsy samples; therefore, it cannot cover a wide range of tissues. In addition, diagnosis and treatment procedures are relatively independent, leading to the mismatch of preoperative and intraoperative information, and surgical operations largely depend on the personal experience of surgeons.Represented by emerging optical imaging and spectroscopic methods, biomedical images at mesoscopic and macroscopic levels provide a good foundation for multimodal rapid and precise diagnosis, such as optical coherence tomography, two-photon microscopy, photoacoustic imaging, Raman spectroscopy and microscopic imaging, and fluorescence spectroscopy and imaging. Because of their excellent real-time performance, high accuracy, and resolution in intraoperative use, many of these methods are known as “optical biopsy”. In terms of treatment, optical methods with high spatio-temporal selectivity, such as laser ablation, photodynamic therapy, and photothermal therapy have gradually entered clinical practice. At the same time, the development of computer vision, precision instruments, automation, and other research fields has promoted more intelligent, accurate, and personalized diagnosis and treatment technology, including artificial intelligence-assisted medical image processing, minimally invasive surgical robots, intelligent treatment planning, and navigation. On this basis, by combining optical imaging and treatment, we can build an intelligent theranostic system, which can break down the barrier between traditional diagnosis and treatment, improving the current surgical process. The accurate intraoperative diagnosis results are directly used for treatment planning and control, which can achieve intelligent, quantitative, and accurate lesion clearance. These emerging technologies are of great significance for the diagnosis and treatment of tumors and other major diseases in clinical practice. Therefore, summarizing the existing studies regarding emerging optical theranostics technologies is necessary to guide the future development and clinical transformation of this field.Progress In this paper, the research progress of intelligent precise optical diagnosis and therapy technology, specifically for malignant tumor theranostics, is reviewed based on three aspects: 1) optical imaging and intelligent diagnosis methods (Fig. 2); 2) precise optical treatment methods (Fig. 4); 3) optical diagnosis and therapy instruments and theranostic methods (Fig. 6). Through intelligent optical diagnosis, the location of lesions could be automatically determined through computer-aided image processing, and we can plan and control precision optical treatment using theranostic algorithms and hardware systems. There are various optical imaging methods used in clinical or preclinical experiments, and some clinical optical diagnosis standards are established preliminarily. However, most doctors have not been trained to read optical images (or spectra); thus, computer-aided automated or quantitative diagnosis is currently the most appropriate method (example given in Fig. 3), which involves quantitative parameter extraction, machine learning, deep learning, and other methods. We focus on several conventional mainstream optical diagnostic modalities with intelligent diagnostic algorithms, including fluorescence and imaging spectroscopy, Raman spectroscopy and microscopy, optical coherence tomography, and photoacoustic imaging. Then, we describe several emerging optical treatment methods, including laser ablation, photodynamic, photothermal, and other light-activated therapies. Precision theranostic devices and methods are divided into four categories and reviewed: imaging field enlargement, improving image quality, multimodal imaging, and the integration of diagnosis and treatment.Conclusions and Prospects Optical diagnosis and treatment of major diseases, especially integrated diagnosis and treatment technology, can considerably improve the clinical processes and treatment prognosis. We expect that intelligent, quantitative, and accurate optical diagnosis and treatment technology will play a more significant role in human life and health, promoting the development and progress of clinical diagnosis and treatment of malignant tumors.

Significance Photoacoustic tomography (PACT) is a novel medical-imaging modality. During the imaging process, biological tissues are irradiated by nanosecond ultrashort light pulse. Fast energy deposition in tissues causes thermoelastic expansion and generates ultrasound emission. Such emissions can be detected by ultrasonic detectors. The penetration depth of PACT (>5 cm) is much higher than that of most optical-imaging modalities, approaching that of ultrasonic imaging. Therefore, PACT has wide potential applications in areas such as blood pressure monitoring, cancer detection, and small-animal studies.PACT reconstruction requires knowledge of distribution of speed-of-sound (SoS). In practice, acoustic properties of biological tissues are inhomogeneous and unknown, resulting in image degradation in PACT. In its simplest implementation, PACT reconstruction assumes single SoS for both biological tissues and surrounding acoustic-coupling medium (i.e., water in most cases). However, considering that the SoS inside soft tissues varies from 1350 m/s (fat) to 1700 m/s (skin), such an assumption can sometimes be too idealized, resulting in splitting, blurring, and distortion of structural features. Furthermore, the SoS of a range of tumors is much higher than that of normal tissues. Therefore, imaging degradation is much severe in tumor imaging.To solve this problem, a more rigorous acoustic model is required during the reconstruction process. Some studies have employed ultrasound devices for directly imaging the distribution of SoS. However, the most effective method is the joint reconstruction of initial sound pressure (IP) and SoS. Presently, there are several methods for joint reconstruction. Each method has advantages and disadvantages and is effective in different scenarios. Herein, we introduce several methods developed by our teams and summarize their advantages and disadvantages, supporting the biomedical application of PACT.Progress The ring-array PACT system (Fig. 1) is widely used in IP-SoS joint reconstruction. Most joint-reconstruction methods are based on delay-and-sum (DAS) or back-projection (BP) reconstruction.Several conventional joint-reconstruction methods have been developed, including dual-SoS, passive element, and model-based methods. Each of the methods has disadvantages and cannot meet practical application demand.We have developed four joint-reconstruction methods, including feature coupling (FC), multisegmented feature coupling (MSFC), adaptive PACT (APACT), and signal compensating (SC) methods. The FC method, separates ring arrays into two halves. Two images are reconstructed using signals detected by the two halves separately. The correlation coefficient between the two images is then calculated to measure their similarities. The aim of optimization is to maximize the correlation coefficient. In vivo experiments have shown promising results (Fig. 2). The MSFC method further separates the ring array into eight subarrays. In numerical studies, the MSFC method has shown better reconstruction results for both IP and SoS distributions, with lower computational complexity (Fig. 3). The APACT method, inspired by adaptive optics methods widely used in optical imaging, estimates the inhomogeneity-induced wavefront distortions of photoacoustic signals in the frequency domain. The SoS distribution is calculated based on the estimates of the wavefront distortion. In vivo experiments have also shown promising results (Fig. 5). Numerical studies have further shown the advantages and disadvantages of the APACT method compared with the FC method. In summary, when using the FC method, prior knowledge of the distribution of SoS is vital. However, currently, the APACT method works well in the absence of prior knowledge (Fig. 6). The SC method utilizes the characteristics of electronic impulse response (EIR). In photoacoustic imaging, the EIR of ultrasonic detectors has positive and negative peaks. For the reconstructed IP images, when the positive peak detected by one detector is superposed by the negative peak detected by the opposite detector, the intensity of the reconstructed image is the lowest. Therefore, by minimizing the intensity of the reconstructed IP image, the inhomogeneity-induced wavefront distortion can be estimated. Fourier transform is applied to the reconstructed image to further analyze the relationship between delay time and image intensity in different directions. Numerical studies have shown promising results (Fig. 7).Conclusion and Prospect Although PACT is a promising imaging modality for various biomedical applications, a better solution to the joint-reconstruction problem is needed. In summary, there are several methods for joint reconstruction, and each is effective in different scenarios. However, all these methods are designed for ring- or hemisphere-array systems, which limits their applications. Therefore, further research on joint reconstruction in linear array and multimodal systems is required to promote the development of this imaging modality.

Objective Although the acquisition of single-molecule localization microscopy (SMLM) includes various noises and background information, completely removal of structural noise is difficult for current denoising algorithms (e.g., the spatial wavelet algorithm and the extreme value-based emitter recovery algorithm) employed in the preprocessing of the reconstruction, thus decreasing the quality of reconstructed super-resolution images. To address this challenge, we develop a new background denoising algorithm based on the time-domain iterative wavelet transform (TDIWT), which can process a batch of SMLM datasets with different signal-to-noise ratios (SNRs) by adaptively selecting the appropriate levels and iterations. This algorithm can provide a new approach for adaptive batching SMLM data structural background.Methods This denoising algorithm based on TDIWT includes two main parts. First, the appropriate level and iteration parameters of TDIWT are adaptively selected for different datasets to balance the time consumption and signal-noise separation effects by calculating the SNR of the dataset. Consequently, time-varied values of each pixel are calculated using TDIWT with selected parameters to separate the signal and background structural noise. The main steps of TDIWT calculation are described by (1) extracting the intensity of the signal from each pixel in a stack in the time domain; (2) acquiring the approximate coefficient via wavelet decomposition and then using it for wavelet reconstruction to fit the background curve; (3) estimating the reconstructed signal that is higher than the background curve and employing wavelet decomposition again; (4) repeating the process until the background fitting data is acquired; (5) outputting separated signal and background image according to the image size (Fig. 1).Results and Discussions The simulated results demonstrate that the separation of signal and background using the TDIWT algorithm is more efficient than that using the other denoising algorithms (i.e., extreme value-based emitter recovery, Gaussian filter, background estimation based wavelet transform, median filter, and rolling filter) by evaluating the direct visualization and the quantitative parameters including structural similarity index measure (SSIM) and peak signal-to-noise ratio (PSNR), as shown in Figs. 3 and 4. The SSIM and PSNR of the TDIWT algorithm are 29.9%, 68.5%, 226%, and 33.3%, 34%, 50.8% higher than that of the spatial wavelet algorithm (i.e., background estimation based wavelet transform) using SNR10, SNR6, and SNR2 datasets, respectively. This can be explained by the fact that the intensity of the signal varies rapidly, but the background structural noise varies gradually in the time domain. This advantage of the TDIWT algorithm is more noticeable under the low SNR with a strong structural background. The normalized intensity of signal near strong structural noise is calculated, as shown in Fig. 3, illustrating that the separated signal using the TDIWT algorithm is the closest to the simulated signal compared with the other algorithms and demonstrating the improved accuracy of signal extraction. In addition, the experimental data acquired using our easySTORM system and the real reference data from an open single-molecule localization website are employed to further evaluate the developed algorithms. The reconstructed tubulin images show a continuous state using the TDIWT algorithm and a discontinuous state using the other algorithms from the same dataset with strong structural noise, as shown in Fig. 5. Figure 7 also demonstrates that the TDIWT algorithm could more effectively remove the structural noise.Conclusions In this study, we have developed a new denoising algorithm based on a time-domain iterative wavelet algorithm, which can process a batch of SMLM datasets with different SNRs by adaptively selecting the appropriate levels and iterations. This algorithm can provide an accurate signal extraction from the noisy background, thus improving super-resolution image reconstruction. Under the simulation datasets, the results have demonstrated that the structural similarity index and peak SNR of processed datasets using the TDIWT algorithm are increased by 226%, 50.8%, and 58.5%, 16.6% compared with that using the spatial wavelet and time extremum emitter recovery algorithm, respectively. In addition, the experimental data acquired using our easySTORM system and the data from the open single-molecule localization website have been employed to evaluate the algorithms. The reconstructed tubulin images have shown a continuous state using the TDIWT algorithm and a discontinuous state using the other algorithms from the same dataset, verifying the superiority of the algorithm. This denoising algorithm based on TDIWT can provide a new approach for adaptive batching SMLM data structural background.

Objective Functional near-infrared spectroscopy (fNIRS) is an effective neuroimaging tool used to directly determine changes in oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (HbR). This technique offers portable and radiation-free alternatives to conventional neuroimaging modalities, such as functional magnetic resonance imaging, positron emission tomography, and electroencephalograph. However, current portable fNIRS systems have limited detection sensitivity due to the employment of photodiodes working in analog mode. To cope with the adversities, we propose a portable two-wavelength continuous-wave fNIRS-topography system based on lock-in photon-counting technology to be applied in cognitive neuroscience and brain-computer interface (BCI) studies in a daily environment. The proposed system has a good prospect of application in faint activation detection by integrating the parallel measurement capability derived from lock-in technology and the high sensitivity derived from photon-counting technology. Thus, the proposed system should provide a noninvasive route, reasonable temporal resolution, and high-sensitive information for studying fNIRS-BCI.Methods In this study, the proposed portable fNIRS system possesses four pairs of source- and detection-optodes, which are matched with the configurations of a nonoverlapping source-detector array to conduct experiments. Source-optode bundles two single-mode fibers with a core diameter of 9 μm connected to two laser diodes (LDs) at 785 and 830 nm wavelengths. Besides, a modulator with eight square wave signals of different frequencies is designed based on a field-programmable gate array (FPGA) kit. The modulated light reaches the cerebral cortex and is subject to refraction, scattering, and absorption by HbO and HbR. A part of the light is redirected to the scalp, where HbO and HbR concentration changes are detected by the detection module in turn, which adopts a photomultiplier tube with a linear range of 5.0×10 6 s -1 and a dark count of 600 s -1 as the core device. A lock-in photon-counting demodulator is designed based on FPGA to achieve parallel signal demodulation and detection in all sampling channels. Besides, the intensity of each LD can be automatically adjusted using a digital potentiometer (AD5259) for adaption to different subjects. Wireless communication and rechargeable batteries are used to ensure portability. All the mentioned components and printed circuit boards are fixed in a portable case with a volume of 23.6 cm×11.0 cm×20.5 cm, which is lightweight and miniaturized. Results and Discussions A series of phantom and in-vivo experiments have been implemented to examine the effectiveness of the proposed portable fNIRS-topography system. The phantom experiments showed that the proposed system has excellent stability (Fig.3), linearity (Fig.4), and anticrosstalk ability (Fig.5). For the in-vivo experiments (Fig.6), we adopt two stimulation paradigms: breath-holding (BH) and mental arithmetic (MA) to evaluate the system. The complete dataset is synchronously acquired at a sampling frequency of 4 Hz. Then, changes in the perturbed HbO and HbR concentrations are calculated according to the modified-Beer-Lambert-law. The frequency spectrum of the measurements is analyzed using the Fourier transform, which provides a theoretical basis for the bandpass filtering (0.018--0.3 Hz), and the spectrum peak (0.02333 Hz) is close to the stimulation frequency (Fig.7). By further analyses of these spectra [Fig.8(a) and Fig. 9(a)], we strengthen the actual activation frequency induced by the stimulation. The results show that the proposed system can accurately trace the time-course of the global activation perturbation by BH stimulation [Fig. 8(b)] and the partial activation perturbation by MA stimulation [Fig.9(b)]. Besides, the optical topography (OT) image of the measurements from the MA paradigm showed that the activation region is roughly located at the center of the left half of the prefrontal lobe [Fig.9(c) and Fig. 9(d)].Conclusions In this study, we developed a portable fNIRS-topography system for the applications of BCI based on lock-in photon-counting technology, which has the advantages of high sensitivity and moderate time resolution. A two-layered brain phantom is employed to evaluate the system. The results showed that the proposed system has excellent stability, linearity, and anticrosstalk ability. Besides, the proposed system is used to measure the perturbed hemoglobin concentration in the prefrontal lobe during BH and MA stimulation paradigms. The results showed that the proposed system can track changes in hemoglobin concentration. The frequency spectrum of the measurements is analyzed, and the spectrum peak (0.02333 Hz) is close but not equal to the stimulation frequency (0.025 Hz). The probable cause of this situation is the hemodynamic response delay (about 2--3 s) in the brain. The image reconstructed by OT during the MA stimulation paradigm showed that the activation region is roughly located in the center of the left half of the prefrontal lobe. We analyzed the entire experimental process and confirmed that simple training before experiments enhances the system performance. In future studies, we will design more stimulation paradigms, e.g., sports and idea recognition, to further explore the potential of fNIRS-BCI in clinical application.

Objective Er∶YAG laser crystals can produce laser at a wavelength of 2.94 μm, which is close to the infrared absorption peaks of water and hydroxyapatite. Laser at a wavelength of 2.94 μm possess numerous advantages in the ablation of biological tissues and the cutting of hard tissues such as bones and teeth. In clinical applications, erbium lasers are mainly used in two modes: free-running and Q-switched. However, free-running erbium lasers have a pulse width of a few hundred microseconds. Long pulses used to affect tissues cause heat diffusion into the surrounding healthy tissues resulting in damage or necrosis. Due to the low gain of 2.94 μm erbium laser crystals, it is difficult to obtain Q-switched erbium lasers with high pulse energy at high repetition frequency. The low ablation efficiency caused by low pulse repetition frequency limits their efficacy in dental treatment. To solve the problems mentioned above, we have developed a sub-pulse sequence mode laser at a high repetition frequency. In this mode, a standard long pulse is divided into several short sub-pulses with the same sub-pulse interval. This enables the sub-pulse sequence mode to deliver short, high finesse pulses with a photoelectric conversion efficiency of long duration pulses without sacrificing the ablation precision of short duration pulses.Methods We set four groups of sub-pulse widths as 20, 30, 40, and 50 μs, and the sub-pulse interval time as 85 μs. The repetition frequency of the laser was 20 Hz. An Er∶YAG crystal rod with 4 mm diameter and 104 mm length was used as a laser-active medium. Doping concentration of the Er∶YAG crystal was 50%(atomic fraction) for Er 3+. Two facets of the Er∶YAG rod were antireflection-coated at 2.94 μm. A resonator was formed using two plane mirrors separated by 194 mm. The reflectivity of the high reflective (HR) mirror exceeded 99% and reflectivity of the output coupling mirror was 70%. An insulated gate bipolar transistor module that can control pulse width and laser frequency through the external pulse signal was used in the laser power supply. In addition, the effects of sub-pulse width on erbium laser ablation in sub-pulse sequence mode were investigated. We used the Er∶YAG laser in sub-pulse sequence mode as the light source. The laser beam was reflected toward the dental sample using a 45° reflector. After being focused by a lens focal length(focal length f= 50 mm), the beam vertically irradiated the surface of the dentin. Cooling water mist was not required during the experiment.Results and Discussions A sub-pulse sequence mode erbium laser with high energy laser outputs of 80 sub-pulses per second was developed . When the sub-pulse widths were 50, 40, 30, and 20 μs, the maximum energy values were 671.1, 741.1, 814.1, and 798.8 mJ, respectively. The corresponding maximum slope efficiency was about 1.8% (Fig. 2). Through the experiment of dentin samples ablation, we found that the ablation mass would increase with decreasing sub-pulse widths. When the sub-pulse width was 20 μs, the mass of ablation was 90 mg after 60 s laser irradiation. When the sub-pulse width was 50 μs, the ablation mass was 62 mg. The ablation mass of the former was 45% higher than that of the latter (Fig. 4). Under conditions of 20 Hz repetition frequency, the samples were treated with the sub-pulse sequence mode laser at energy of 45 mJ. With decreasing sub-pulse width, the temperature rise in the pulp chamber decreased. When the pulse width was 50 μs, the temperature reached 42 ℃ within 25 s, but when the pulse width was set as 20 μs, the temperature reached 42 ℃ within 33 s (Fig. 5). In addition, the dentin samples were sprayed with gold and dehydrated to study the cavity structure after ablation before observation with a scanning electron microscope (SEM). When the sub-pulse widths were 20 μs and 30 μs, no carbonization, melting, or debris were observed on the surface of the pot hole, and the lower dental tubules were completely open. However, when the sub-pulse width reached 40 μs or 50 μs, no obvious melting and debris were observed by the scanning electron microscope, but the dentinal tubules were partially sealed (Fig. 6).Conclusions A sub-pulse sequence mode erbium laser at a high repetition frequency was developed, which obtained high energy laser outputs of 80 or 100 sub-pulses per second. The effects of sub-pulse width on erbium laser ablation in sub-pulse sequence mode were investigated. The pulse widths of the sub-pulse during ablation were set to 20, 30, 40 and 50 μs, respectively, and the pulse energy of the laser was maintained at 45 mJ. The influence of sub-pulse width on the ablation mass, the temperature rise in the pulp chamber, and the cavity microstructure were analyzed without cooling water mist.Results indicate that shorter sub-pulse widths can increase the ablation mass, reduce the temperature rise in the pulp chamber, prolong the operation time, and improve efficiency. In addition, improved cavity microstructure and more open dentinal tubules were obtained, which are both beneficial to adhesive repair and treatment.

Gastrointestinal tumors are one of the most common types of tumors. Emerging photoacoustic imaging technology can sharply capture the information of the nourishing blood vessels surrounding the tumors, which may give potential contributions to accurate clinical diagnosis. The matched vessel enhancement algorithm can effectively highlight the vessel network. However, the detection angle of in vivo photoacoustic endoscopic imaging is limited, which results in obvious vascular structure abnormalities. It is difficult for current enhancement algorithms to effectively enhance blood vessels. Therefore, a three-dimensional vascular enhancement algorithm was developed in this investigation that fuses the information on structure and intensity of the colorectal vessel of rats, based on a self-designed endoscopic photoacoustic imaging system. The results indicate that this algorithm can effectively improve the imaging effect, suppress edge burrs brought about by mechanical vibration, and obtain in vivo high-quality three-dimensional images of the colorectal vessel, indicating that it has potential value in basic medical research and clinical applications.

The fluorescence pharmacokinetic parameters (permeability, etc.) based on dynamic diffuse fluorescence tomography (DFT) can provide reference for studying the dynamic physiological process and pathological information of different biological tissues. The adaptive extended Kalman filter (AEKF) (a method for dynamic analysis) has many advantages, such as precise modeling and multi-parameter online estimation. In this work, the metabolic process of indocyanine green (ICG) in healthy mice liver and tumor-burdened mice subcutaneous transplanted tumor tissue was measured using the dynamic DFT system. Then, we obtained the time-series fluorescence yield images of ICG by DFT method. On this basis, the time-series permeability images of ICG were reconstructed by the AEKF method based on a two-compartment model. The two experimental results verify that the permeability parameters Kpe and Kep of ICG in the tumor are less than that in the liver. Furthermore, the time-series permeability images of ICG also demonstrate that the AEKF method can effectively obtain the real-time and stable ICG pharmacokinetic parameters of complex organisms.

To achieve simultaneous measurements of biochemical properties and physical structures, we proposed an endoscopic probe that combines optical coherence tomography (OCT) imaging and fluorescence ratio imaging. Based on the OCT imaging principle, the center wavelength of the OCT system was determined to be 1300 nm. Based on the absorption and reflection spectra of the selected pH indicator, the excitation wavelength of the fluorescence was determined to be 520 nm. Moreover, the basic structure of the probe was calculated and determined according to the ABCD matrix. The processing of the optical element and actual assembly of the probe were performed based on the theoretical calculation results. Furthermore, the dual-modality system was built to measure the transverse resolution and working distance of the probe. The ability of simultaneous imaging and pH detection was demonstrated on pork intestine. The probe can simultaneously perform OCT imaging and pH measurement with high accuracy. The resolution of OCT imaging in air is approximately 37.3 μm, and the working distance is approximately 13.4 mm. Moreover, the proposed system can measure the pH value of 0.01 units.

Owing to the advantages of optical coherence tomography (OCT), such as high resolution, deep imaging depth, and fast imaging speed, it facilitates a new method for the evaluation of renal status. The renal ischemia-reperfusion (IR) process can cause damage to renal functional units; such damages can be quickly estimated using noninvasive optical imaging in real time. Herein, using spectral-domain OCT (SDOCT) with 1300-nm center wavelength, two- and three-dimensional images of Wistar rat kidneys were collected in vivo. The obtained images clearly show the microstructure of uriniferous tubules in the renal cortex. Moreover, results demonstrate that OCT imaging is prominent in the evaluation of renal status owing to the sensitivity of OCT to IR process.

The major stochastic optical reconstruction microscope (STORM) techniques include data localization and reconstruction algorithms with respect to a large number of images. However, the existing open source algorithms are limited by their slow speed or computer memory when processing an ultralarge dataset, restricting the extensive application of STORM techniques. Therefore, we propose WindSTORM PLUS for performing single-molecule localization data processing using MATLAB and parallel computation. The outcomes obtained using the simulated large datasets demonstrate that the data processing speed of WindSTORM PLUS is greater than those of the existing WindSTORM and ThunderSTORM by 1000%. Furthermore, the memory requirements are reduced by 60% compared with those in case of WindSTORM. In addition, we establish an easySTORM system and conduct a test using some samples to verify the superiority of our algorithm. The time-consuming of WindSTORM PLUS is only 9% of WindSTORM and Gauss-WLS. We believe that this open source algorithm can provide a novel high-speed STORM data processing approach.

In order to study the correlation between the fucoxanthin content of Phaeodactylum tricornutum and its photosynthetic physiological indexes, different monochromatic light-emitting diodes were used as light sources to treat P. tricornutum. The fucoxanthin content, photosynthetic physiological indexes, and the expressions of photosynthesis-related genes were detected, and the correlation among the indicators was examined. The results show that purple light can significantly promote fucoxanthin and chlorophyll a production of P. tricornutum (PPPrbcL gene. Under red, blue, green, and purple light conditions, the expression level of fcpB is significantly increased compared to the control group (PfcpB gene, and negatively correlated with the expression of the rbcL gene. In conclusion, the synthesis and accumulation of fucoxanthin can be promoted by improving the photosynthetic efficiency of P. tricornutum, which can be done by regulating the parameters of rETRmax and the expression of the fcpB gene at different wavelengths.

In this study, we propose an adaptive optics closed-loop control model based on the far-field index gradient, which can be used to stabilize the response matrix based on the recursive least square values. Further, the current system state can be rapidly self-learned using the far-field index gradient. The experimental results denote that the proposed model exhibits real-time online update characteristics; furthermore, the proposed model can adapt to the state of H-S subaperture lack of light or non-ideal centroid detection, which improves the control performance to some extent.

Non-contact ballistocardiography (BCG) is used to measure heart rate (HR) by measuring the periodic pressure of blood on the walls of blood vessels during circulation. This pressure causes the periodic weak mechanical movement of various parts of the body, including the head, which is very weak, and the BCG signal extracted from the body movement has a low signal-to-noise ratio, which limits the measurement accuracy of the heart rate. An optical lever is used to amplify the head motion, and a non-contact high precision heart rate detection algorithm named optical lever amplified BCG algorithm (OLA-BCG) is proposed. In the proposed method, a laser is used as the active light source. A plane mirror attached to the head is used to amplify the head motion. At the same time, the weighted centroid tracking algorithm is used to extract the motion trajectory of the head, and the interference noise is filtered out by independent component analysis to obtain BCG signal. Finally, the extracted BCG signal is analyzed and the heart rate is calculated. Experimental results show that the proposed OLA-BCG can effectively improve the signal-to-noise ratio and measurement accuracy.

In this work, a swept-source optical coherence tomography (SS-OCT) system was constructed using a dual fiber ring structure to obtain the depth spatial information of a planned surgical site in laser ophthalmic surgery. In the proposed system, a dichroic mirror was added to the sample arm to integrate it with a CMOS camera system. After matching the geometric relationship between the coordinates of the OCT system and camera system, several scanning modes, including multi-angle linear scanning and annular scanning, were designed, achieving multimode scanning imaging at any given position of camera video images. The longitudinal resolution of the imaging system was 13.68 μm, while the lateral resolution was 29.8 μm. The imaging depth in the air was 17.25 mm. The measured maximum lateral deviation was 275 μm, and the maximum longitudinal deviation was 70 μm; thus, the requirements of the operation location were met. By using the proposed system, rapid depth information acquisition of the designated parts of the eye is possible. Therefore, the system is suitable for application in ophthalmic disease diagnosis and cataract surgery navigation.

To understand characteristic of the shapes of most tumors and the laser transmission mode as an internal light source during laser interstitial therapy, a double-layered media model in the shape of sphere with an interpolated optical fiber was established. Then, the modes of the photon transmitting in the tissue, at the boundary of the sphere, and on the surface of the inserted optical fiber were set, assuming the photons were launched at the center of the model. Finally, the photon migration in the model was simulated based on the Monte Carlo (MC) method in the Visual Studio (VS) program. The simulation results show that the optical fiber primarily affects the movements of photons that are moving near the surface from which they were launched. The energy absorption by the tissue under the photon-launching surface is greater than that in the above the surface. The absorption of the inner boundary increases with decreasing inner sphere radius. Compared with the traditional MC method, this model has more similarities with a real laser interstitial thermotherapy situation, which is of considerable practical significance for predicting the thermal damage range of laser interstitial thermotherapy.

Cell distribution can be characterized quantitatively using a depth-resolved scattering coefficient calculation method based on optical coherence tomography (OCT). This method uses a single scattering model to obtain a depth-resolved scattering coefficient distribution map, and the law of cell distribution is verified using the histogram statistics of the scattering coefficient. A multilayer scattering medium model is used to verify the effectiveness of the proposed method. The experiments reveal that the scattering coefficient distribution maps can resolve the cell distribution depth and provide a more obvious contrast between the cell and background compared with an intensity map. There are no significant differences in the distributions of the OCT intensity signal histograms of various cell suspensions. The histogram of the scattering coefficient contains the characteristic cell concentration peak, and the degree of deviation between the characteristic peak and background scattering characteristic peak is linear with the cell concentration. The cell distribution in the bio-3D printed hydrogel scaffold detected by the OCT scattering coefficient distribution map corresponds well with the H&E staining results, and the corresponding scattering coefficient histogram distribution exhibits peaks characteristic of the cell concentration.

In this paper, a speckle recovery algorithm for light through scattering media that can achieve focusing at any position in a large field of view is proposed. The transmission matrix of the scattering medium is measured and binarized by simulating the optical path, and the digital micro-mirror device is used to modulate the binary amplitude of the incident light to achieve single-point or multi-point focusing through the scattering medium. Due to the independence of different focus positions, the algorithm can achieve large field-of-view focusing at any position. The simulation results show that the intensity enhancement factor of the focus position increases with the increase in the sampling number. Compared with the traditional three-step phase shift method, an enhancement ratio of 55% can be obtained by the proposed algorithm when the number of sampling is reduced by 1/3, which is 12% higher than that by the three-step phase shift method. The proposed algorithm exhibits great significance for realizing large field-of-view scanning and focusing through the scattering medium, making it applicable in the field of biomedical imaging.

Epilepsy surgery often depends on the accurate positioning of lesions; however, current positioning methods have some limitations. The electrocorticogram (ECoG) in clinical inspection has a high temporal resolution, but its spatial resolution is below the accepted standard. Based on the neurovascular coupling mechanism in the human brain, we propose a new epileptic foci detection method by detecting cerebral microvascular blood flow with microphotodiodes and ultrasound transducers. The results of experiments conducted on animals show that the light signal on the surface of the cortex has good correspondence with the ECoG signal. The spectra of the ultrasound signal also matches that of the electrical signal within a depth of 1 mm below the cortex. Therefore, we believe that this method can improve the spatial resolution of epileptic lesion detection, and it can potentially be used for depth inspection.

In this study, we report a novel stereotactic neurosurgical navigation system based on orthotopic coaxial projective imaging (CPI). The proposed system facilitates automatic registration of the position of the patient, real-time projection of the preoperatively reconstructed surgical target and the planned approach in the surgical field, and precise intraoperative guidance with respect to the target and the approach. The average reprojection error of the system is 0.4 mm at its working distance via a coaxial calibration test, indicating a high photographic-projection coaxiality. The average projection error of the system in a stereotactic projection test is 1.2 mm at different projection angles, indicating a high stereotactic navigation accuracy. In a neurosurgery simulated by using a phantom model, the average projection error of the system is 0.3--3.1 mm in different operational conditions, indicating the technical feasibility of the system for neurosurgical navigation. Unlike the conventional stereotactic surgical navigation systems that require a display screen, the CPI system avoids frequent viewpoint changes between the screen and the surgical field, eliminates the possible operating errors, and improves the surgical efficiency. The proposed system may be applied to surgically treating many neurological diseases, including brain tumors and brain hematomas.

In photoacoustic microscopy (PAM), detection sensitivity is an important factor for determining imaging quality and depth, which can affect photoacoustic imaging applications in biomedical engineering. To improve the detection sensitivity and signal-to-noise ratio (SNR), a miniature amplifier was integrated close to an ultrasound transducer for front-end signal amplification and output impedance matching. An optical resolution PAM was developed based on the fabricated prototype transducer to perform 3D imaging of phantoms and small vessels of the mouse ear. Experimental results show that the SNR is improved by over 10 dB. The proposed PAM has the potential to be used for monitoring and quantitatively analyzing weak physiological changes.

Optical coherence tomography angiography (OCTA) is an important tool for investigating microvascular networks and microcirculation in living tissue. In this study, OCTA was employed for noninvasive in vivo monitoring and assessment of inflammation induced by bacteria in a mouse ear model. Imaging results demonstrated that OCTA can monitor changes in microvascular density and morphology of blood vessels caused by immunovascular responses during the inflammatory process with a high degree of resolution and sensitivity. Distinctly enhanced OCT signals from the mouse ear were observed following bacterial infection owing to an influx of red blood cells caused by the bacteria. A highly dense microvascular network noted in the palms of healthy subjects by OCTA, demonstrates the feasibility of OCTA for the clinical evaluation of inflammation. This method can improve the understanding of the pathological mechanisms of inflammation and can be useful in the clinical evaluation of inflammation.

Photoacoustic imaging, a novel biomedical imaging technique that combines the advantages of optical imaging and acoustic imaging, offers high-resolution biological tissue imaging to facilitate the observation of deeper imaging sites. In other words, it breaks the “soft limit” of conventional optical bioimaging techniques. However, many diseases, especially in the early stage, present no obvious photoacoustic contrast; therefore, it is crucial to identify effective exogenous photoacoustic contrast agents. Here we introduce a novel two-dimensional material, antimonene nanoflakes (AMNFs), which demonstrates great optical absorption from 300 nm to 900 nm as well as excellent photothermal conversion efficiency and photoacoustic performance. This material is expected to be useful as a contrast agent, helping to achieve excellent photoacoustic imaging of ultra-small tumors in vivo.

In this study, we construct a high-sensitivity optoacoustic mesoscopy (OPAM) experimental system with a multi-angle scanning mode that can simultaneously perform high-sensitivity measurements and achieve multi-angle information acquisition. This system is employed to acquire the structural and functional information related to small-animal tumor models. The spatial resolution of this OPAM experimental system is verified via a phantom experiment that satisfies the OPAM imaging requirements. Further, by applying the OPAM experimental system on two types of small-animal tumor models, their structural images and obvious type characteristics are presented. Subsequently, the blood oxygen saturation values of the tumors are obtained using the OPAM experimental system under the dual-wavelength measurement condition. The experimental results denote that the OPAM experimental system can provide valuable reference and guidance for oncology research and that the proposed system exhibits considerable application prospects in the field of biomedical research.

Herein, a novel method for generating parallelized fluorescence depletion patterns based on optical wedges is proposed. Optical wedges and matching reflectors are used to control the stimulated emission depletion (STED) beam inclination angle of the tube lens object space to make full use of the numerical aperture of the microscope objective to produce parallelized fluorescence depletion patterns with small periodicity. Simulation results show that a square lattice-like parallelized fluorescence depletion pattern with periodicity as small as 282.0 nm×283.6 nm is generated when the wavelength of the STED beam is 760 nm and numerical aperture of the microscope objective is 1.4, thereby achieving relatively high imaging resolution.

Rapid detection of foodborne pathogens is one of the most effective ways to overcome food safety problems. To realize a rapid, efficient and label-free detection and classification of foodborne pathogens, this study aims to improve the performance of existing optical fiber confocal backscattering spectrum system. Through this process, the light field diameter is reduced to fit small biological samples, and single spectrum level detection can be achieved. Furthermore, the backscattering micro-spectrum of three categories of common foodborne pathogens (Salmonella enteritidis, Escherichia coli, and Salmonella typhimurium) with similar morphology is measured without labels. A multivariate analysis model is established by combining principal component analysis (PCA) and fuzzy cluster analysis (FCA) at the characteristic wavelength range of 500--800 nm. Results show that the top five principal components contain 80.41% characteristic spectral information. The scores of the top five principal components are taken as the variables for the FCA. The accuracy of 100%, according to the degree matrix of membership, is achieved for the clustering results of three kinds of bacteria. Also, results show that optical fiber confocal backscattering spectroscopy, combined with PCA and FCA, can be used to analyze and classify a single spectrum rapidly, efficiently, and without labels.

Formation of β-Amyloid (Aβ) plaques is one of the most significant pathological features of Alzheimer’s disease (AD). Detection and degradation of Aβ plaques are crucial in AD treatment. When Aβ monomers aggregate to form plaques, they produce strong autofluorescence. In this study, we investigate label-free imaging of Aβ plaques by using the nonlinear optical imaging method and study their degradation via photodynamic effect of the photosensitizer. Moreover, we study the relationship between photosensitizers with different concentrations and degradation effect of Aβ plaques. Corresponding liposomes are prepared and they are applied to the degradation of Aβ plaques. The potential applications of label-free optical imaging and photodynamic therapy in AD research are discussed, and a new way for optimizing AD diagnosis and treatment is provided.

Whispering gallery mode is a type of optical mode where photons move in a quasi-two-dimensional plane, and the total reflection occurs at the boundary of the microcavity without reflecting out of the cavity. This mode has a high Q value and small mode volume, and it is extremely sensitive to changes in the surrounding environment. A broadband fluorescence can be transformed into narrow-spectrum laser output by using the whispering gallery mode. In this paper, polystyrene microspheres doped with the dragon green fluorescent dye are used as whispering gallery mode optical microcavity. Through the phagocytosis of cells, the fluorescent microspheres reach inside cells and then are pumped by nanosecond pulsed laser to achieve the output of whispering gallery mode laser in cells. In comparison with the laser output in the pure-water environment, a redshift of the intracellular fluorescent microsphere whispering gallery mode resonance emission can be observed, and the redshift is related to cell type; therefore, it can be used for unlabeled identification of cell type.

As a new molecular imaging technology, Cherenkov-excited luminescence scanned imaging (CELSI) has merits of high spatial resolution and large imaging depth, therefore showing a potential for monitoring the physiological changes of tumors during radiotherapy. In our previous work, we developed a tomographic technique for CELSI based on Tikhonov method, which is problematic to reconstruct accurate fluorescent targets with position depth larger than 3 cm or with low contrast. To overcome this problem, we develop a sparse reconstruction method for tomographic CELSI based on approximate message passing. To demonstrate the merits of the proposed algorithm, we compare it with traditional Tikhonov regularization and three sparse based reconstruction algorithms. Our results show that the proposed method can achieve best performance in terms of mean-square error and contrast noise ratio.

In this paper, the ultrasensitive detection of an alpha-fetoprotein (AFP) is performed using a combination of two-dimensional (2D) surface-enhanced Raman scattering (SERS) and an AFP aptamer. We construct SERS "hot spots" through complementary base-pairing between substrates modified with AFP aptamer and silver nanoparticles modified with aptamer complementary sequence. The complementary adaptor sequence is also modified using Raman signal labeled molecule ROX, but the addition of the AFP damages the structure of nano-gap "hot spots", resulting in a decrease in intensity of the SERS signal. The ultrasensitive quantitative detection of AFP is realized using the changed working curve of the SERS signal of ROX. The detection limit of this method is 145 fg/mL, which is one order of magnitude higher than that of the traditional clinical detection method. The designed AFP SERS probe also exhibits good specificity and anti-interference ability. These results show that this new approach may provide a rapid and effective method for the accurate detection of AFP.

This study evaluated 8 unstained human coronary tissues ex vivo using spectrum- and time-resolved multiphoton microscopy. First, according to the spectra, the elastin fibers and collagen fibers in the coronary arterial intima can be separated clearly. Second, the ratios of the two types of fiber signals were calculated to assess changes in the relative content of the collagen and elastin fibers in the coronary arterial wall caused by an atherosclerotic lesion. Third, we assessed biochemical variations of the elastin fibers in the coronary atherosclerotic tissues by measuring fluorescence lifetime and found that the coronary atherosclerotic plaque has a lower mean fluorescence lifetime than a normal tissue. This study demonstrates that spectrum- and time-resolved multiphoton microscopy can effectively identify coronary atherosclerotic plaques, thus indicating its potential as a novel research tool for studying coronary arteriosclerotic lesions in the future.

The low temporal resolution of stochastic optical reconstruction microscopy (STORM) limits its ability to observe dynamic events in live cells. Further, the post-processing analysis and reconstruction algorithms have an important effect on super-resolution images. In this study, we report a new noise-correction principal component analysis method for single-molecule localization microscopy against fluorescent spot overlapping and excessive background noise in a single frame of images owing to high-density labeling and high camera-sampling frequency. The proposed method can improve the positioning accuracy of existing localization methods by pre-processing the raw images acquired by the single molecule localization microscopy before reconstruction. In addition, this method can accurately distinguish the overlapping molecules. Therefore, it is suitable for samples exhibiting a high fluorophore density. Thus, the proposed method improves the temporal resolution of super-resolution imaging, providing a powerful technical support for the STORM imaging of live cells.

In this work, the effect of terahertz (THz) radiation on the excitability of hippocampal neurons is studied by changing the neuronal membrane potential and using hippocampal neurons in Sprague Dawley (SD) rats irradiated by a THz source with frequency of 0.1 THz and power density of 2.65 mW/cm 2 for 5, 15, and 25 min, respectively. The results show that THz irradiation for 15 and 25 min causes a significant depolarization of the hippocampal neurons, thereby increasing neuron excitability. To explore the mechanism behind this THz radiation-induced excitability of neurons, the intracellular concentrations of Ca 2+, Na +, and K + are determined. The results show that Ca 2+ and Na + concentrations in the hippocampal neurons increase and K + concentration decreases after irradiation by the THz source. Our study shows that the irradiation with frequency of 0.1 THz and power density of 2.65 mW/cm 2 can promote neuronal excitation by regulating the concentration of charged ions in the hippocampal neurons. This finding may provide the preliminary experimental basis for the application of THz radiation technology to the biomedical field.

The development of fluorescence lifetime analysis method suitable for low photon count is of great significance for the evelopment and application of fast fluorescence lifetime imaging microscopy (FLIM). In this paper, we consider the fluorescence lifetime analysis, inspired by the compression sensing algorithm in high-density single molecule localization microscopy, as a sparse inverse problem, and we propose an alternating descent conditional gradient (ADCG) based method for fluorescence lifetime analysis. Through the analysis of simulation data and experimental data, we demonstrate that the ADCG-FLIM algorithm can be appropriately implemented to analyze fluorescence lifetime even in the case of low photon count, thereby benefiting the development and application of live cell fast FLIM.

A new characterization method, namely membrane voltage measurement method, is proposed. Because the recovery time of membrane potential is dependent on the size of optoporation, establishing the relationship between the size of cytomembrane optoporation and the laser energy threshold can provide theoretical support for importing different exogenous substances into cells. In this study, gastric cancer cells are cultured with gold nanoparticles. On the premise that cells are not affected by the toxicity of gold nanoparticles, gastric cancer cells incubated with gold nanoparticles are irradiated using a nanosecond-pulsed laser with different energies. Propidium iodide and calcein-AM are used for staining verification of perforated cells. The results indicate that optoporation of cell membrane can be successfully achieved with 400 nanoparticles (diameter of 100 nm) per cell and 20 mJ/cm 2 energy density by 532 nm pulsed laser, without obvious dead cells. During the optoporation, the membrane potential is measured using optical mapping technique. It is found that the membrane potential firstly increases and then restores with 50 mV maximum increment and 250 s recovery time. These results confirm that the cell membrane damage can be recovered by optoporation and characteristiced by membrane potential change.

As noninvasive tools of high-resolution micromanipulation and force measurement, optical tweezers have been widely applied to researches in life science. Holographic optical tweezers show higher flexibility than the conventional single-trap optical tweezers in producing arbitrarily patterned trap arrays with the help of the spatial light modulator, which has significant potential in application to the biomedical research. In this paper, we review the basic principle of holographic optical tweezers, hologram algorithm, and the progress in the applications of holographic optical tweezers in biological research. We expect that this review will provide a helpful reference to the community that will apply holographic optical tweezers to the biological research.

Photoacoustic imaging (PAI) has been widely used in the fields of cardiovascular and cerebrovascular research, cancer diagnostic, brain science, and early diagnosis to diseases owing to its distinguished characteristics, such as noninvasion, high resolution, and high contrast. With the recent progress in opto-electro-mechanical technology, the miniaturized PAI technology has developed rapidly. This study focusses on the miniaturization of PAI system and provides a review for the development of PAI from the viewpoint of hand-held, wearable, portable, and endoscopic PAI devices.

Rapid histological imaging of pathological tissues with sufficient diagnostic information has great potential to aid doctors in intraoperative decision making. Stimulated Raman scattering (SRS) microscopy is an emerging label-free imaging modality capable of obtaining histological images of tissues without the need for time-consuming tissue processing, such as fixing, sectioning, and staining. An increasing number of studies have demonstrated SRS microscopy as a “virtual histology” tool for rapid diagnosis of various diseases. In this review, we focus on the basic principles and current developments of SRS microscopy as well as its applications for rapid tissue histology.

Rare earth doped upconversion nanoluminescent materials (UCNP) can convert low-frequency photons into high-frequency photons, usually near-infrared light excitation and visible light emission. This unique optical property makes it promising for biological applications. In recent years, UCNPs have made significant progress in the imaging and sensing fields. This paper reviews the important progress in synthesis, surface modification, and bioassay using UCNPs, covering important advances in biological detection, and including upconversion fluorescence-based temperature, ions, small molecules, and important proteins and nucleic acids.

Combing the advantages of optical and ultrasound imaging, photoacoustic tomography is an emerging, fast growing biomedical imaging modality, possessing high resolution, superb contrast and deep tissue penetration. Photoacoustic microscopy (PAM) is an important embodiment of photoacoustic tomography. It has been extensively studied for preclinical and clinical applications by taking advantage of its ability to provide anatomical and functional information of live bodies noninvasively. To make people better understand the emerging technique, this review reviews the development status, latest technology, and application advances of PAM. We first introduce the working principle and typical system configurations and then discuss major advances in spatial resolution, imaging depth, scanning methods, signal detection methods, and multimodality imaging. Subsequently, we review the current status of biomedical applications of PAM. Finally, technical challenges of PAM in the translation to clinical settings are discussed.

Functional imaging techniques have been continuously developed based on optical coherence tomography (OCT). OCT angiography (OCTA) technique employs the relative motion of red blood cells and surrounding tissues as the endogenous label for blood flow. By analyzing the dynamic optical scattering characteristics of spatially scattered signals in OCT, the blood flow motion information is extracted. Thus, OCTA enables an in vivo, label-free, and 3D high-resolution blood flow imaging by distinguishing dynamic blood flow areas and surrounding static tissues in three-dimensional space. The optical attenuation coefficient (OAC) algorithm evaluates the degree of tissue damage and accurately reveals tissue activity by analyzing the attenuation characteristics of spatially scattered signals in OCT with depth. OCTA technology and OAC algorithm enable in vivo, label-free, 3D high-resolution, and long-term monitoring of stroke progression in real time, including real-time assessment of ischemia and blood flow reperfusion, and tissue damage and its degree of recovery. A systematic review is made on the development of OCTA technology and OAC algorithm, and the progress of related stroke research is further introduced. The above-mentioned OCT technology has important application value in the field of biomedicine.

Terahertz (THz) waves are ideal for biomedical imaging because of its natural non-ionization properties, sensitivity to moisture, and penetration depth in biomedical tissues. The THz quantum cascade laser (QCL) has advantages of high power, good-quality spot, fast modulation rate, and tiny size. Compared with traditional biomedical imaging systems, the biomedical imaging systems based on THz QCL have a superior signal-to-noise ratio, higher imaging resolution, faster imaging speed, and more compact structure. This study reviewed the progress on the research of biomedical imaging systems based on THz QCL. Furthermore, this study also summarized the advantages of THz bioimaging, THz QCL biomedical imaging, biomedical imaging systems, and biomedical imaging goals. Moreover, the direction of future developments is viewed.

Minimized probe is a common requirement in endoscopic optical coherence tomography (OCT). We introduce the development of mainstream designs based on ball lens, fiber lens, graded index fiber, free form lens and free-lens, summarize their advantages and disadvantages, and put forward some suggestions for miniaturization of the probe. The development of probe with extended depth of focus (DOF) poses significance on imaging subcellular structure of human internal organs. We review several important techniques of DOF extension suitable for miniature probes, among which the probe based on mode interference is believed to have great potential because of its easy fabrication, compact structure, high light transmission efficiency, optimized working distance and DOF, and uniformity of axial light intensity.

Antibacterial photodynamic therapy (APDT), which is a non-invasive treatment method, is based on the interaction between near-infrared light and a nontoxic photosensitizer concentrated at the lesion site to generate reactive oxygen species (ROS). These species are highly cytotoxic in virtually all bacteria. With the development of biomaterials and nanotechnology, advances in nano-biotechnology have resulted in the optimization of biocompatibility and biosafety of small-molecule photosensitizers. The targeting ability has improved and the quantum yield under illumination has significantly increased. Nanotechnology exhibits excellent clinical application prospects with respect to antimicrobial therapy. In this review, recent applications and developments of APDT are summarized by combining various modification strategies and mechanisms for nanophotosensitizers.

Tumor is an important problem that modern medicine needs to overcome. Early screening and treatment of tumor require immediate attention in clinical practice. Therefore, this paper describes the basic principles and detection characteristics of several common tumor marker nanobiosensors based on nanoparticle, nanowire, nanotube, and nanoarray material. Core-shell nanoparticles have abundant modification function. Nanowires are often made into field-effect tube to detect tumor markers. Based on the scale effect, nanotubes are primarily used in transport of carriers and detection platform. Metal and metal-oxide nanoarrays can detect cancer cells using the principle of electrochemical impedance spectroscopy. In addition to the advantages and application characteristics determined by different structures, nanobiosensors have the overall advantages of rapid and convenient detection of tumor cells and low detection limit compared with traditional detection methods. Therefore, nanobiosensors offer great potential in medical detection and tumor research.

Optogenetics is an emerging technique that exploits light to control cells by combining optics and genetics techniques. In optogenetic systems, cells are genetically modified to express photosensitive proteins and consequently become responsive to light pulses. Optogenetics has revolutionized neuroscience research by facilitating selective and rapid control of targeted neurons expressing light-gated ion channels. In addition to light-gated ion channels, photosensitive proteins based on light-gated protein-protein interactions are widely used in optogenetic research. In this review, we discuss these common photosensitive proteins and summarize optogenetic applications in optical control of gene expression, phase separation, biosynthesis, and organelle distribution based on light-gated protein-protein interactions.

Owing to its inherent ability to overcome the spectral crosstalk, high sensitivity, and non-destructivity characteristic, fluorescence resonance energy transfer (FRET) quantitative measurement (spFRET) method based on spectral unmixing has been generally regarded as the most promising approach of live-cell FRET measurement. This paper first briefly introduced the quantitative FRET measurement method and the related research advances on FRET technology. Second, the principle, development process, and robustness of spFRET based on linear separation of emission spectra (Em-unmixing) and linear separation of excitation emission spectra (ExEm-unmixing), respectively, were introduced. Finally, the potential advantages of the two spFRET technologies in live-cell FRET applications was also provided and discussed.

Second harmonic generation (SHG) is a novel optical imaging technology that has been recently developed. SHG has attracted considerable attention as a new tool for the biological structure and durable tracking. The SHG technology eliminates many disadvantages associated with the classical fluorescent probes. It is an ideal in vivo imaging method and exhibits good biomedical application prospects. In this study, we introduce the principle of SHG and its imaging device, classify the SHG media, review the application of SHG in biomedical imaging, and prospect future opportunities and challenges.

The technological development in modern optical imaging and fluorescent labeling has provided important tools for obtaining high-resolution three-dimensional (3D) structural information about biological tissues. However, the opaque nature of most biological tissues limits the light penetration depth, which limits their applications for large tissue specimens or organs. In recent years, optical clearing methods that employ various physical and chemical means have been proposed for reducing light attenuation and improving the imaging depth, thereby providing novel perspectives for 3D imaging of large samples or whole organs. This paper reviews the tissue optical clearing methods for imaging whole organs from three aspects: in vitro optical clearing methods for tissues, whole-mount labeling methods, and 3D imaging techniques.

Photodynamic therapy (PDT) has been widely used as a precise targeted therapeutic modality in the clinical treatments of malignant tumor and benign diseases. The utilization of advanced optical imaging techniques in the real-time quantification of PDT dosimetric parameters is essential in predicting PDT efficiency and providing personalized and precise treatment. In this study, four important parameters in PDT dosimetry were introduced (i.e., photosensitizer, ground-state oxygen, singlet oxygen, and vascular response). Furthermore, the advanced optical imaging techniques currently developed for monitoring the aforementioned dosimetric parameters are summarized, and the advantages and limitations of each optical imaging technique is comparatively analyzed. Finally, challenges in clinical translation of optical imaging techniques to the clinical application of PDT are briefly discussed.

As a new imaging technique, coherent Raman scattering (CRS) microscopy has been widely used in chemical structure and composition analysis because of its advantages of label-free, high specificity, and on-invasion. In recent years, the mutual cross-over and integrated development of photonics, biomedicine, and microscopic imaging technology has greatly promoted the application of CRS microscopy in biomedicine. This paper briefly introduces the basic principle of CRS microscopy and its classification, then explains the most widely used implementation of CRS, and summarizes the recent applications of CRS microscopic imaging in biomedicine, including detection, lipid analysis, and protein conformation change. Finally, the future development of CRS is discussed.

Optical coherence microscopy (OCM) utilizes a coherent detection method for optical microscopy. Having advantages, such as high axial resolution, high signal-to-noise ratio, and label-free imaging in optical coherence tomography (OCT), the OCM can achieve a micron-scale spatial resolution by utilizing a high-power objective for obtaining high lateral resolution. Initially, the basic principle and implementation scheme of the OCM technology are introduced; subsequently, the principles and research progress of the OCM technology around the world are summarized. This study also examines some advanced OCM technologies considering the problems that how to realize ultra-high-resolution imaging and that the depth of focus limits the imaging depth. The OCM technology has broad application prospect in biomedicine, material detection, and other fields.

Animal studies play very important roles in the basic science research. Recently, several optical imaging methods, which are widely adopted in human retinal imaging, have been successfully applied into animal retina researches. By providing high-resolution cellular details about the retina without the need for histological section, these optical imaging methods provide powerful tools for researchers to study using the animal retina. Correspondingly, several new technologies have been developed for animal retina researches, which are also applicable for human retinal imaging, or provide new insights in understanding the human retina function mechanism. Based on their own research experiences in in vitro optical imaging methods for mouse retinas, the authors review several latest break-through technology developments in animal and human retinal imaging with high resolution and with a focus on demonstration of the “can-do” ability of the current technologies, hoping it will provide new insights to promote the advancements for ophthalmic imaging in both species.

Fiber-like structure is one of the basic structures found in biological tissues. The spatial orientations of fiber-like structures change with the initiation and progression of some diseases. In this study, we present a brief overview of quantitative orientation analysis methods for fiber-like structures within biological tissues and main applications of these methods. We especially focus on the research progress of spatial orientation information in important disease models, including wound healing, osteoarthritis, breast cancer, peritoneal metastasis, and brain injury. Additionally, we explore the relations between tissue structure and function via specific engineered tissues. A highly sensitive and highly accurate description of the fiber-like structures within biological tissues serves as a novel method for studying disease initiation and progression, shows potential for early disease diagnosis, and improves our understanding of the mechanisms underlying some disorders. Finally, future potential applications of the orientation analysis methods are explored.

Of late, with the emergence of new optical devices and technological advances in data processing, polarization techniques are being increasingly used in biomedicine. Mueller matrix calculus is suitable for describing the polarization properties of biomedical specimens because of its mathematical completeness and compatibility with common optical equipment. Compared with traditional non-polarization optical methods, Mueller matrix polarimetry is sensitive to the scattering induced by subwavelength structures and can provide more information about anisotropic optical properties, including the birefringence and diattenuation of a sample. In this review, we introduce Mueller matrix calculus and related technologies that have great application potential in biomedical studies, including the Mueller matrix decomposition and transformation methods, transmission Mueller matrix microscopes, backscattering Mueller matrix imaging equipment, Mueller matrix endoscopes, and polarization staining techniques. Further, we summarize the improvements in clinical diagnosis made using Mueller matrix polarimetry, such as detection of liver cancer, gastrointestinal cancer, and breast ductal carcinoma tissues. As a label-free, noninvasive, quantitative, and rapid imaging method, Mueller matrix polarimetry has broad application prospects in biomedical studies and clinical diagnosis.

In the biomedical field, to reduce the cost and dependence on advanced devices and to realize multi-dimensional image analysis for unlabeled samples, including spectra and structures, a multispectral microimaging system with multi-channel LEDs was independently developed based on narrow-band LED light source technology. The spectral resolution of the system was 20nm over 420--680nm, with spatial resolution better than 2μm and an imaging range of 520μm × 416μm under 13× magnification. To verify feasibility of the system for clinicopathological analysis, multispectral images of mouse skin squamous cell carcinomas were collected, for both in situ and normal skin tissues. Excitingly, cell structure was clearly observed using the multispectral image system. Spectral information extracted from the image sequence shows that reflectance of the cancerous nucleus has significant difference with that of the normal nucleus in the visible band, allowing the two types of cells to be effectively distinguished. These results indicate that LED illumination-based multispectral imaging systems are promising alternatives to replace traditional, expensive, and complex multispectral imaging systems and play an important role in pathological analysis.

In order to reasonably select corneal contact lenses of different materials, based on the principle of geometric optical imaging, a corneal imaging model based on contact lenses is established, and the influences of contact lenses with different refractive indexes on corneal imaging quality are analyzed. By using the idea of reverse optical imaging, a paraxial optical system for detecting imaging quality is designed, the corneal contact lenses of different materials and thicknesses are added respectively, and the influences of corneal contact lenses of different materials on the imaging quality are quantitatively analyzed. The effective focal length of the optical system is 18.36 mm, the total length is 36.49 mm, the image height is 2.48 mm, the modulation transfer function value is close to limit diffraction, and the distortion of the full field-of-view is less than 0.1%. ZEMAX simulation results show that the material of the contact lens is PMMA and the thickness is 0.05 mm, which can meet the imaging and wearing requirements of contact devices in augmented reality techniques.

In this work, using the model of random phasor sums, the intensity probability density distribution of the signal of an optical coherence tomography (OCT) structure is described, the probability density distribution of the amplitude difference signal is derived, and the threshold model of the dynamic and static regions of the difference image is theoretically determined. A set of swept source optical coherence tomography systems that can scan and image the microvascular of the human skin is used to generate binarized images through a threshold model, combining the existing cross-correlation images based on volume data and binarized images in the laboratory. Results show that the proposed model can reduce the speckle noise and obtain clear structural information.

The dual phase lagging (DPL) non-Fourier heat transfer model can reflect the transient interaction process between pulsed laser and biological tissues. However, in many literatures where the DPL model is used to study the heat conduction mechanism of biological tissues, there exist both Fourier and non-Fourier boundary conditions and thus many induced conclusions are contradictory. In this paper, the control equation based on the DPL non-Fourier model is adopted and the Fourier and non-Fourier boundary conditions are derived. Meanwhile, the analytical solutions under the above conditions are obtained by integral transformation and Laplace transformation. The biological tissues are taken as an example and the calculation results show that as for the non-Fourier control equation, the predicted temperature distribution in tissues based on the non-Fourier boundary condition is in accordance with the energy conservation law, while the result based on the Fourier boundary condition is not. The conclusions on the temperature rising amplitude and temperature rising rate are opposite for the two kinds of boundary conditions. Moreover, the thermal damage predicted under the Fourier boundary conditions is overly conservative and obviously lower than that under the non-Fourier boundary conditions. Finally, from the point view of energy conservation, the DPL non-Fourier boundary condition is just the DPL energy conservation equation of boundary, while the Fourier boundary condition is the energy conservation equation of the Fourier model. The Fourier control equation of bio-heat conduction should be matched with the Fourier boundary conditions, while the non-Fourier control equation of bio-heat conduction should be matched with the non-Fourier boundary conditions.

As a new type of model animal, zebrafish is more and more widely used in the brain-related researches. However, there is a lack of high-resolution imaging technologies for the in vivo characterization of the brain of zebrafish from its infancy (>7 days old) to adulthood. In this study, optical coherence tomography (OCT) is used to give in vivo imaging of zebrafish brains after hatching 21, 45 and 100 d. The results show that the imaging depth and resolution of OCT are both enough to visualize the whole brain of zebrafish from three age groups, and the brain structural features of OCT images match well with the sectional staining results. Both the 2D and 3D OCT results quantitatively show that the zebrafish brain increases significantly in 80 d, however due to tissue atrophy, the sectional staining results can not accurately or quantitatively evaluate the brain''s development. This study shows that OCT can be used as a tool for efficient in vivo imaging and used for the brain''s development research based on zebrafish.

Based on the histological characteristics, a three-dimensional model of the vein and its surrounding tissues was constructed. The light distribution of the irradiated vein was simulated by diffusion approximation theory, the biological thermal equation was solved by finite element method to obtain the temperature distribution throughout the tissue, and the damage caused by laser irradiation was calculated according to the Arrhenius equation. The photothermal response of a radial fiber and a radial 2ring fiber was compared. The effects of laser power, pull-back speed, linear endovenous energy density and venous diameter on the therapeutic effect of the radial 2ring optical fiber were discussed. The results show that the temperature of the tissue irradiated by the radial 2ring fiber is lower than that by the radial fiber, and the adhesion between the fiber and vascular wall could be reduced. When the tissue is irradiated by the same linear endovenous energy density, it is more secure in the lower laser power treatment. The larger the vein diameter, the higher the linear endovenous energy density is required to achieve the therapeutic effect. The proposed model is helpful to better understand the action mechanism of the endovenous laser ablation.

Intravascular optical coherence tomography (IVOCT) is of great significance for early diagnosis of cardiovascular diseases and imaging probes are the core components of IVOCT systems. For this purpose, an IVOCT probe driven by a miniature propeller was proposed in this paper. Instead of using electric devices such as micromotors that provided power for beam scanning in traditional endoscopic probes, the probe utilized the kinetic energy of the fluid that flushed away the blood in the imaging of the IVOCT system to drive the propeller installed at the probe end, thereby driving the right-angle prism on the propeller shaft to rotate and realizing the scanning imaging of beams for the vessel walls. Moreover, we improved the driving efficiency of fluid by optimizing the design of the propeller. For the probe, the outer diameter is 1.5 mm and the highest scanning speed can reach 491 r/s. Finally, the imaging ability of the IVOCT system integrating the probe was well verified by the clear tomographic images of the samples like white tapes, green onion tubes, and in vitro artery vessels of chicken hearts.

Fluorescence immunochromatographic quantitative detection technology has been widely used in the field of clinical detection, such as for the screening and detection of the new coronavirus pneumonia. To improve the detection accuracy, a fluorescence immunochromatographic quantitative detection method based on fluorescence microscope digital image processing is proposed. Initially, the luminous flux loss equation of the microscopy system is constructed. Then, the RGB components in the original image are extracted according to the digital image features output by the area array CCD, and the quantum response rate curve of the area array CCD is fitted after weighting to compensate. Finally, the relative intensity of the fluorescence signal is obtained, and the concentration of the analyte is inversed according to the intensity of the fluorescence signal. After experimental verification, it can be observed that the coefficient of variation of the test results is 3.04%, and the linear fitting coefficient is >0.99. This detection method can accurately detect the analyte with a minimum mass concentration of 0.1 ng/mL. It is suitable for CCD imaging fluorescent microscope system and has certain reference significance for fluorescence detection.

The resolution and imaging quality of super-resolution fluorescence imaging significantly depend on the number of fluorescent molecular photons collected during the experiment, as well as the background noise. To obtain fast super-resolution fluorescence microscopy imaging under low photon count and high background light conditions, the proposed convolutional neural network is employed to restore the signal with extremely low signal-to-noise ratio (SNR) and combined with the reconstruction network to perform super-resolution imaging. The results show that the fluorescence signal can be effectively recovered under the condition of low signal-to-noise ratio, the peak signal-to-noise ratio can reach 27 dB, which is significantly better than the other two algorithms. The proposed method can also cooperate with Deep-STORM reconstruction network to obtain fast super-resolution imaging under low SNR conditions. The normalized mean square error of the reconstructed result is 7.5%, and the resolution is significantly improved compared to the other similar algorithms. Additionally, the reconstruction results under experimental conditions verify the ability of the proposed method and provide a feasible solution for fast super-resolution fluorescence imaging under weak signals.

Photothermal therapy is a non-invasive, targeted, and new technology, but the existing photothermal therapy technology cannot monitor the temperature distribution of the target area in real time, and the open-loop laser control method not only increases the difficulty of treatment but also causes irreversible damage to normal tissues around patient''s lesion. This paper proposes a photothermal therapy method based on precise control of photoacoustic temperature. The proposed temperature imaging algorithm was studied, the concept of photoacoustic temperature sensitivity factor was proposed and a closed-loop temperature control algorithm was designed based on the factor. Finally, a new photothermal treatment system was designed based on precise control of photoacoustic temperature, and phantom experiments were conducted. The experimental results show that the photothermal therapy method based on the precise control of photoacoustic temperature can realize the non-contact accurate measurement and control function of the target zone temperature. The system adjustment time is within 10 s and the temperature control steady-state error is within 0.7 ℃. Additionally, the results show that the photothermal therapy method based on the precise control of photoacoustic temperature can be used as a more accurate and efficient auxiliary method in the field of photothermal therapy.

Herein, we propose an imaging method based on frequency modulation and spatial coding to overcome the problem associated with fluorescence molecular tomography data acquisition methods, improve the data acquisition scheme, and reduce data acquisition time. In this method, the excitation beam is split into several sub-beams and used as multipoint excitation source. These sub-beams are modulated to different frequencies and then simultaneously incident at different points on the target surface. At the detection side, the emergent light of the target is first directed to a single photomultiplier through a spatially coded mask. According to the compressed sensing theory, the distribution of fluorescence signals on the target surface can be obtained by changing the mask mode and conducting sparse reconstruction and recovery. We design the corresponding simulation experiment to evidence the proposed methodology. Result shows that the method can better restore the original image, which proves the feasibility of the proposed method.

Cancer research has increasingly focused on developing appropriate tumor cell invasion models and developing a quantitative method to monitor tumor cell invasion. In this study, a three-dimensional tumor invasive model with >1 mm thickness is constructed. An ultra-wideband spectral domain optical coherence tomography system is used to detect cell migration and invasion dynamics, and the in vitro invasion process of tumor cells is characterized by the change of cell migration distance and matrix material decomposition. The quantitative detection of tumor cell migration distance based on peak change of the optical coherence tomography scattering interface is combined with three-dimensional images to quantify the matrix surface curvature, thickness, and overall volume change, thereby realizing the characterization of the matrix material decomposition and deformation information during tumor cell invasion. The changes of cell cluster positions caused by tumor cell invasion and morphological changes of matrix materials are matched with hematoxylin-eosin staining sections and laser confocal results, which verifies the feasibility of optical coherence tomography for detecting tumor-cell invasion. Three-dimensional tumor models under different nutrient gradients and different pH microenvironments are utilized. The established optical coherence tomography system accurately quantifies the migration distance of tumor cells and surface curvature and overall volume change of matrix materials at different time and in vitro microenvironments. Compared with hematoxylin-eosin staining and the laser confocal imaging method, the proposed optical coherence tomography-based method enables the continuous monitoring of the invasion process of tumor cells, thereby providing a more comprehensive view of tumor-cell migration and invasion mechanisms.

Diffuse correlation spectroscopy (DCS) is a rapidly growing optical technology to noninvasively assess the tissue blood flow index. We develop a multichannel DCS topography system based on a multi-tau photon correlator, which comprises a long coherence length laser, a photomultiplier tube, and a photon correlator. The multi-tau photon correlator structure can obtain the intensity temporal correlation curve with high resolution and large dynamic range. Combining the imaging characteristics of the system, the constrained nonlinear optimization algorithm based on the analytical solution of the correlation diffusion equation is used as the model. The model is applied to match data between actual measurements and model predictions calculated by analytically solving the correlation diffusion equation in semi-infinite geometry. Finally, the dynamic phantom experiments demonstrate that the imaging system can distinguish different flow rates of liquid medium to reconstruct a two-dimensional image of flow rate distribution.

We uses a high-resolution (micrometer scale) photoacoustic microscopic imaging system to continuously monitor early-stage tumor angiogenesis in the ear of mice and its response to anti-angiogenesis therapy. Further, a three-dimensional Hessian-matrix-based vascular extraction algorithm is proposed for the quantitative photoacoustic imaging of tumor vessels to improve the tumor vessel extraction accuracy. Subsequently, the morphological changes in various parameters, such as the diameter, density, and tortuosity, of the tumor vessels are quantitatively analyzed. Furthermore, the potential of high-resolution photoacoustic quantitative imaging to study the pathological mechanisms of tumors and other diseases characterized by vascular changes is demonstrated in this study.

In conventional photoacoustic (PA) imaging, the tissue absorption coefficient is usually considered to be a non-directional scalar constant, and its anisotropic optical absorption characteristics are ignored. Herein, we propose an anisotropic PA microscopy (A-PAM) technique that uses two linearly polarized light beams perpendicular to each other as the excitation source for PA imaging. Subsequently, we develop the A-PAM imaging system and verify the feasibility of the proposed method using phantoms that exhibit different forms of anisotropic optical absorption. Furthermore, we demonstrate the imaging ability of this method using biological samples that exhibit anisotropic absorption. Results show that the proposed method can be easily implanted into the conventional PAM imaging system, expanding the range of information extracted using conventional PA imaging.

By using a 4f (f is the focal length) optical setup and a charge coupled device camera, the sample position is tracked. The mechanical drift is compensated by the nano-translation table which ensures the sample always at the beam waist of the light sheet and thus an optimal image is obtained. With the proposed method, the mechanical drift of several nanometers can be compensated. By using the home-made light sheet fluorescence microscopy, the long-time imaging of fluorescent microspheres with diameters of several micrometers is acquired, which confirms the feasibility of the proposed method.

By selecting laser power, laser pulse frequency and scanning speed as optimization variables, we establish a multi-objective optimization model of laser closure process parameters in vitro skin tissue. Based on MATLAB software, we use second generation non-dominant sequencing genetic algorithm (NSGA-II) to find the Pareto optimal solution set, obtain the optimal process parameters, and then analyze the response sensitivity of optimization objectives to the variation of process parameters. Under the optimized process parameters, the tensile strength of the incision is tested and the microstructure is analyzed. The results show that the incision tensile strength has high sensitivity to the laser process parameters, and the laser power has significant effect on the incision tensile strength and the tissue peak temperature. The proposed optimized process can achieve the in vitro skin tissue closure in full-thickness. In the case of tissue peak temperature decreasing, the tensile strength of in vitro skin tissue incision is 5.6% higher than that of single-objective optimization.

In comparison with the traditional suturing, laser biological tissue welding has the following advantages: shorter operation time, faster wound healing, less tissue damage, and no thread removal. To improve the strength and quality of laser soldering of biological tissues, increase the laser absorptivity in the direction of full-thickness, and explore the effects of dyes on the strength and thermal damage of laser soldering of biological tissues, we use the bovine serum albumin solution as the matrix, chitosan as the stabilizer, and indocyanine green and methylene blue as dyes. We use a Nd∶YAG laser (1064 nm) to weld the skin in vitro with flux and compare the welding effect of flux. Results show that indocyanine green and methylene blue are significant organic chromophores for laser welding. They promote the efficiency of photothermal conversion, improve the welding strength, and reduce thermal damage.

In this study, an analytical expression is derived based on the extended Huygens-Fresnel principle for the spectrum of a Gaussian Schell-model (GSM) beam that propagates in biological tissues. The spectral change of the GSM beam during propagation is studied based on the normalized spectrum and the relative spectral shift. Results show that the spectral blue shift, red shift, and rapid transition can be observed when the GSM beam propagates in biological tissues, and they are dependent on the off-axis distance, propagation distance, type of biological tissue specimen (specifically the refractive-index structure constant of tissue turbulence), and spatial correlation length. As the propagation distance increases, the refractive-index structure constant increases, meaning that the turbulence of biological tissue becomes stronger. Meanwhile, as the spatial correlation length increases, the position where spectral rapid transition occurs is farther and the transition qualities correspondingly decrease; furthermore, the spectral rapid transition becomes increasingly weak and the propagation position where a transition can be observed from the spectral red shift to blue shift becomes increasingly distant. With increasing values of the refractive-index structure constant and the spatial correlation length, the off-axis distance associated with the spectral rapid transition will also increase, i.e., the distance between the observation position and the propagation axis will increase.

Functional near-infrared spectroscopy imaging has become the preferred choice as a neuroimaging technique of brain function research. To obtain the imaging system with high sensitivity, large dynamic range and high temporal resolution, we develop a multi-channel near-infrared brain functional imaging system based on improved lock-in photon-counting. The light source module consists of 16 laser diodes with wavelength of 785, 808 and 830 nm, respectively, which are modulated by square wave with frequency space of 252 Hz. The detection module includes nine photon counting photomultiplier tubes. This system combines the ultra-high sensitivity of the photon-counting technology with the simple parallelism of the digital lock-in detection based on square wave modulation mode, and system performance meets requirements. The linear correlation coefficient can reach 0.9989, cross talk between channels is negligible. The system has strong anti-interference ability and the ability to locate accurately.

Limited-projection fluorescence molecular tomography (FMT) allows rapid reconstruction of three-dimensional distribution of fluorescent targets in animals through shorter data acquisition times. However, due to less projection data, the limited-projection FMT undergoes severe ill condition. In order to reduce the ill condition of FMT reconstruction and improve the reconstruction speed, we propose a reconstruction method for limited-projection FMT. Considering the characteristics of the sparse distribution of the target of FMT, this method combines with smoothed l0 norm and feasible region of prior information. A continuous function approximates the smoothed l0 norm, which improved the calculation speed. And the feasible region of the prior information improves the precision of the recovered results. The reconstruction results of digital mouse model show that the position error of the reconstructed image is less than 1 mm at 3, 6 and 9 excitation points and the reconstruction time is shortened, and the reconstruction time under the 3 excitation points is 8 s. The reconstruction result of physical phantom further verifies the feasibility of this method in practical FMT applications.

Based on the design method of response surface methodology, pulsed laser welding process experiment of in vitro skin tissue is performed to obtain the tensile strength and peak temperature data of tissue incision. On the basis of single factor experiment, the multivariate nonlinear mathematical regression model is established by using laser power, spot moving speed and laser frequency as the three influencing factors. Correlation coefficients of the regression model are obtained by analysis of variance and regression analysis as follows: correlation coefficient of incision tensile strength is 0.9131, correlation coefficient of incision peak temperature is 0.9985. The results of model analysis show that the main effect and interactions of laser power, spot movement speed and laser frequency have a great influence on the incision performance. The main effect that has the greatest influence on the tensile strength of incision is laser power, and the interaction effect is laser power and spot movement speed. The main effect that has the greatest influence on the peak incision temperature is laser power, and the interaction effects are laser power and spot movement speed, laser power and laser frequency, and spot movement speed and laser frequency. Finally, the optimal combination of laser process parameters is obtained based on the regression model. The experimental results show that the response values of regression model are consistent with the experimental results, and the incision strength meets the requirements.

Transdermal drug delivery by microneedles combines the advantages of both injection and transdermal drug delivery techniques, greatly enhances the percutaneous absorption of macromolecular drugs with almost no damage to skin, thus has good prospect. However, this technology is still in its infancy, and it is necessary to study the penetration depth of microneedles in the skin and absorption/release behavior of drug particles by means of imaging. A swept source optical coherence tomography system is developed, which uses the Bessel beam, generated by a circular Dammann grating, to illuminate samples. This system exhibits high lateral resolution along an axially extended focal range, the effective depth of focus of the measured system is 1.68 mm and the lateral resolution around the confocal position is 3.61 μm, which can meet the imaging requirements for transdermal drug delivery by microneedles. The proposed system is used to image the dissolving microneedles before and after inserting into the skin, the edge of microneedles, penetration depth and microchannels left on the skin are clearly visible, and the dissolution process of microneedles in skin is observed.

Tissue phantoms with different optical parameters are designed to study the influence of absorption and scattering on tissue fluorescence and diffuse reflection spectra. An empirical recovery algorithm is optimized to correct the influence of absorption and scattering and obtain the intrinsic fluorescence spectrum of tissues. The results reveal that the empirical recovery algorithm (experience parameters kx and km are 0.9 and -0.8, respectively) can effectively reduce the influence of absorption and scattering on the fluorescence intensity, and the fluorescence intensity is linearly correlated with the concentration of fluorescence components. When we apply spectral recovery algorithm to the screening of diabetes based on skin tissue fluorescence spectrum, the results reveal that, comparing to the fluorescence spectrum before recovery, the area under receiver operating characteristic (ROC) curve increases from 0.54 to 0.81; besides, the sensitivity also increases from 38.6% to 77.6% when the specificity is 70.6%. Therefore, this study makes a major contribution to research on clinical application by optimizing fluorescence spectrum empirical recovery algorithm with tissue phantoms.

A spectral calibration method for optical coherence tomography (OCT) is proposed. The method is implemented by introducing an interference signal with a fixed optical path difference (OPD) in the Fourier domain OCT system. The sample interference signal and the fixed OPD signal are acquired simultaneously. Then the fixed OPD signal is obtained from the mixed signals through a filter step, and its phases are calculated to calibrate the interference signal of the sample in the system. We theoretically analyze the feasibility of the proposed method. In a 100 kHz swept source OCT system, the spectral calibration experiments with a mirror as the sample are performed at different depth positions. The point spread functions and the axial resolutions are obtained. Compared with the results using the light source clock, the proposed method has a better effectiveness.

Absolute blood flow velocity and orientation are measured by a dual-mode imaging technology using photoacoustic microscopy and optical coherence tomography (PA/OCT). The blood flow velocity perpendicular to the direction of the probe beam is measured by photoacoustic correlation spectroscopy. The blood flow velocity parallel to the direction of the probe beam is measured by the Doppler OCT. Then the absolute velocity and orientation of blood flow are obtained. For the same fluid sample with different tilt angles, the standard deviation of the absolute blood flow velocity which is 1 mm·s-1 measured by PA/OCT is 0.02 mm·s-1 and the correlation coefficient between the blood flow orientation measured by PA/OCT and the actual flow orientation is 0.997. The experimental results show that the PA/OCT is suitable for measuring absolute blood flow velocity and orientation.

Bioluminescence tomography (BLT) is a new optical molecular imaging technique that utilizes the light intensity information on the surface of biological tissues to reconstruct the three-dimensional distribution of the internal bioluminescent source. The source reconstruction of BLT has serious morbidity due to the limited measurements of light intensity and the complicated structure of biological tissue. A multilevel adaptive finite element method for BLT is proposed, which is combined with the permissible regional-shrinking strategy to improve the quality of the reconstruction. Simulations of single-source and double-source based on the digital mouse model are designed to assess the localization ability of light source and the quantification ability of energy density of the method, respectively. The results show that the proposed method can significantly improve the positioning accuracy and energy density of the light source.

High resolution tomography images of human ex vivo kidney and colon tissues are obtained by using full-field optical coherence tomography (FFOCT) system. The experimental setup is based on a Linnik-type interferometer illuminated by a low coherence lamp. The theoretical resolution of the system is 0.5 μm. Series of interferometric images of sample and reference mirror are obtained by a charge-coupled device (CCD) and four-step phase-shifting algorithm. This experimental setup is used to image human kidney, and kidney tissue structures are successfully identified based on characteristic of histological slices of the kidney. The system is used to image human colon tissue and colonic adenocarcinoma tissue. On the basis of histological slices images, the ability of the FFOCT system identifying human cancer tissue is verified with the analysis of the colonic tissue and colonic adenocarcinoma tissue tomography images. The results of the study lay the foundation for future clinical diagnosis and application for FFOCT.

As basic units of structure and function of the biological nervous system, neurons encode, transmit, and integrate information through discharge activities neuron, plays an important role in life activities. Based on the dynamic nature of neuronal discharge activity and phase imaging technique, we discuss nondestructive and label free imaging method for living cells and their inner substructure. According to phase information of neuron model, we study the characteristics of static morphology and dynamic discharge activities. The optical imaging simulation technique is used to establish the neuron phase model and obtain the information of its phase distribution. Starting from the physical meaning of the phase function, the substructure of the model is analyzed. Considering dynamic effect of the change of intracellular ion concentration in discharge activities on refractive index and phase information, the method of visualizing the dynamic process with phase information is discussed preliminarily. For the complex heterogeneous phase volume model, the local static morphological information on the substructure and phase characterization result of dynamic discharge activity on the sample are obtained without phase decoupling by introducing the heterogeneous contrastive compensation idea. The availability of the method is verified by simulation analysis. The results show that the optical phase characterization method for neuronal discharge characteristics and morphology is nondestructive, label-free, and quantifiable.

Dynein, tubulin, and chromosome play important roles in oocyte meiosis. However, the traditional fluorescence microscopy is limited by the diffraction limit and has low resolution, which cannot meet the imaging requirements of oocyte meiosis. Firstly, the normal maturation system of oocyte in vitro and abnormal maturation system under the action of sodium orthovanadate (SOV) are established. Then the confocal fluorescence microscopy and stochastic optical reconstruction microscopy (STORM) are applied to study the localization of the two important proteins of dynein and tubulin and the morphology and structure of chromosome during the oocyte meiosis. The fluorescence imaging results show that the co-localization of dynein, spindle assembled by tubulin, and the morphology and structure of chromosome can correctly reflect the different stages of oocyte meiosis in the normal system. In the SOV treated groups, the abnormality rate of spindle structure increases, and there are typical spindle structures such as barrel, slender, regiment, disorderly, piriform, and multipolar. The abnormality rate of chromosome structure also increases. The STORM results clearly present the structural information of the spindle, and the 3D STORM results reveal the disorder level of abnormal spindle. This method provides an imaging approach with higher resolution for the research of the oocyte meiosis.

The Raman spectra detection of human skin fibroblasts is studied by the growth of human skin fibroblasts on the surface of tapered fiber probe with surface enhanced Raman scattering (SERS) substrates. The tapered fiber probe is prepared by melt-pulling and chemical-etching method. The gold nanoparticles are cured by chemical self-assembly on the surface of the probe to prepare a tapered SERS fiber probe. The human skin fibroblasts are cultured on the surface of the SERS fiber probe inside the mixture of gold sol and culture medium. Then, using a micro-Raman spectrometer, we obtain the surface-enhanced Raman spectra of the human skin fibroblasts with remote detection method, meanwhile, we obtain the SERS spectra of the human skin fibroblasts with and without swallowing gold nanoparticles with direct measurement method. Based on the results of remote and direct detections, we analyze the Raman peak attribution of human skin fibroblasts, and the internal components information corresponding to the Raman characteristic peaks. The use of the tapered fiber probe allows the remote detection going deep inside the tissue, which may help the application of on-line SERS measurements in biomedical research and diagnosis. While Raman spectrum measurement of the human skin fibroblasts also provides means for the in vivo study on the mechanism of low power laser exposure in delaying wound healing.

An axial adjustable common-path interferometric phase imaging system with simple structure is proposed based on the theory of interference imaging. In this design, making full use of the reversibility of the optical path and the reflection and refraction characteristics of the splitter prism, the incident beam is split into two parallel beams by a prism. One beam is incident on the sample and reflected by the reflecting stage as object light, and the other beam is directly reflected as reference light. The interferograms can be captured by combining object beam with reference beam through the same beam splitter. The interferometer can achieve different types of interference by adjusting the angle between the layer of the beam splitter prism and the optic axis. Taking Fourier transform and three steps phase shift norm method as examples, the phase of the interference fringe is recovered, and the performance of the system is evaluated by the analysis of the results. The feasibility of the proposed design for biological cells phase imaging is demonstrated. The system has the characteristics of simple structure, easy operation and low system error, which can provide an easy and simple method for label-free morphological detection of homogeneous cell.

Bioluminescence tomography (BLT) is a promising optical imaging modality, which has the advantages of low cost and high sensitivity. Efficient and stable inverse algorithm is the key to push it into application. To overcome the high ill-posedness of the inverse problem of BLT, we propose a nonconvex L1-2 regularization based on reconstruction method. A convex difference algorithm is used to solve the involved nonconvex functional minimization problem. In each iteration, an alternating direction method of multiplier with adaptive penalty is adopted to solve the problem efficiently. Phantom experiments of single-source and double-source on a digital mouse model are designed to assess the effectiveness and robustness of the proposed method. Comparison study with three typical reconstruction algorithms is also conducted. Simulation results show that the reconstruction results using L1-2 regularization have the optimal location accuracy under different experimental settings.

An imaging detection system is designed to achieve quantitative measurement of the concentration of fluorescent immune-chromatographic test strip. Using 365 nm ultraviolet light emitting diode (LED) as the excitation light, we capture the clear image of fluorescent immune-chromatographic test strip by the hand-held zoom microscope camera. Genetic algorithm on the base of Otsu is used to segment the image according to the characteristic of relatively fixed position of the detection line and the quality control line. Then, the background noise is removed by the fluorescence region localization method. The segmented fluorescence image background is filtered out and the gray values of the detection line and the quality control line are calculated. Finally, the eigenvalues of the fluorescence region are calculated to realize the quantitative analysis for the concentration of the fluorescence test strip. The experimental results show that the fluorescence detection system has good repeatability. Five different concentrations of fluorescent test strips are tested for ten times. The variable coefficients of the results are less than 0.5%. The fitting degree of the standard curve reaches 0.99944, and the rapid quantitative detection is realized.

The vitro photodynamic therapy(PDT) inactivation efficiency of HL60 cells based on cadmium selenide-doped titanium dioxide nanoparticles modified by folic acid (FA-CdSe-TiO2) is investigated and the mechanism of folic acid modification to enhance the PDT effect of CdSe-TiO2 nanoparticles is discussed. The CdSe-TiO2 nanoparticles are prepared by hydrolysis deposition method, and FA-CdSe-TiO2 nanoparticles are prepared by surface modification method. The structure and optical properties of the nanoparticles are characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet visible absorption spectrum and so on. The cell viability is measured by CCK-8 method. The intracellular reactive oxygen species (ROS) levels are analyzed by fluorescence probe labeling technique, and the ultrastructure of the cells is observed by scanning electron microscopy. The results show that FA-CdSe-TiO2 nanoparticles have no significant change in cytotoxicity compared with CdSe-TiO2 nanoparticles in the darkroom condition. However，under the light condition, FA-CdSe-TiO2 has a great increase in cell growth inhibition rate. When the ratio of folic acid is 1.0, the PDT efficiency is 84% at 18 J/cm2 light irradiation. Folic acid surface modification increases the uptake efficiency of HL60 cells to the nanoparticles, and the level of ROS in the cells is increased, thereby the PDT inactivation efficiency of HL60 cells is enhanced.

Compared with the traditional beam-splitting elements, the noncollinear acousto-optic tunable filter (AOTF) has many special merits, such as small size, high stability, flexible and easy to tune, convenient for signal reception and processing. It has high application value in spectral imaging field. In this study, the noncollinear AOTF is connected with the converted microscope, and a hyperspectral microscopy imaging system is built. With the system, the rapid microscopic spectral imaging for lung cancer tissue is studied in the visible range. In the experiments, the relationship between the acoustic frequency and the diffracted optical wavelength loaded on AOTF is got, and the theoretical results coincide well with the experimental data. A series of microscopy images and corresponding narrow band spectra of lung cancer tissue are received at central wavelength. The results indicate that the system keeps a well spectral resolution performance in the working waveband. By comparing the lung cancer tissue images under different wavelengths, it is found that obvious image drift is not observed, which indicates that the image has high stability. Lung cancer tissue images of each central wavelength all present good clarity. The comparison of lung cancer tissue image and the analysis results of luminance curve and transmissivity curve show that the best contrast and clarity performance of the images are in the range of 503.45-590.12 nm. It is mainly because the different intrinsic constituents and structures in different areas induce different absorptivities of the signals with different optical wavelengths in lung cancer tissues.

We propose a hand-held frequency sweeping optical coherence tomography system, which can image microvasculature in human skin. We get the cross-section and en-face images using power intensity differential (PID), speckle variance (SV), and differential standard deviation of log-scale intensity (DSDLI) algorithms, and compare the practical imaging resolutions. The results show that, compared with images reconstructed by PID and SV algorithms, the image reconstructed by DSDLI algorithm is clearer and shows more blood vessels and detailed vascular information.

Photobleaching induced by excitation light limits the application of confocal microscopy for long-time observation of biological samples. A new imaging approach, controllable light exposure-confocal microscopy (CLE-CM), is proposed. CLE-CM has two thresholds decided through pre-experiments and detects the feedback of sample pixel value at set intervals. The feedback is compared with upper and lower thresholds. By spatially controlling the light-exposure time of objective pixel according to the results of comparison, CLE-CM exploits fluorescent information in a more efficient way and reduces photobleaching without decreasing image quality. Two scan series of 11 successive CLE-CM images and standard confocal images show that, CLE-CM reduces 52.62% of photobleaching in bovine pulmonary artery endothelial (BPAE) cells compared with standard confocal at the 11th image. The effect of bleaching attenuation depends on the fluorophore distribution. CLE-CM decreases photobleaching markedly through the reduction of excitation-light dose, and increases the number of good-quality images that can be captured continuously by confocal microscope.

As for deep tissues, the field of view of a single correction in the widely used adaptive optics is limited and the refresh rate of a spatial light modulator or a deformable mirror is also limited. Therefore it is difficult for them to satisfy the requirement of large field-of-view (FOV) rapid correction of wavefront distortion and thus that of high-speed imaging. A parallel wavefront correction method is proposed based on the conjugate adaptive optical correction system and the coherent optical adaptive technique. In this method, without increasing the number of refresh times of spatial light modulator, the large FOV of one-time correction can be realized by means of the parallel measurement of wavefront distortion of multiple guide stars, which provides a feasible reference solution for the high-speed and high-resolution imaging of deep tissues. The simulation results show that when 9 guiding stars are used, the effective FOV of a single correction by the proposed method is about 4.7 times than that of the conventional method for a thin scattering medium composed of 5 layers of random phase masks, and 4.6 times than that of the conventional method for 120-μm thick mouse brain tissue. Moreover, the proposed method can further improve the FOV of one-time correction by increasing the number of guide stars while the correction time does not significantly increase, which has broad application prospect in the large FOV imaging of in vivo biological tissues.

A handheld swept optical coherence tomography system capable of rapidly imaging subcutaneous human microvascular is established. Three algorithms are used to reconstruct the blood flow distribution images: power intensity differential (PID) without logarithmic compensation, logarithmic-compensated power intensity differential (LCPID), and logarithmic-compensated power intensity differential with motion threshold (MTPID). Then, microvascular en-face images obtained by three imaging algorithm are compared. The results show that the LCPID algorithm can reveal deeper blood flow information, and the MTPID algorithm can get more details of the blood flow distribution and high image resolution. So, the superiority of MTPID algorithm has significance for the application of OCT system in biomedical optics.

Velocity of blood flow is measured by photoacoustic correlation spectroscopy. The effects of the laser repetition frequency and the angle between the blood flow direction and incidence laser propagation direction on the measurement of velocity of blood flow are studied. Research results show that the faster the blood flow velocity, the higher the laser repetition frequency required. When the blood flow orientation is perpendicular to the direction of incident laser propagation direction, the range of velocity of blood flow that the system can measure is 0.059-92.3 mm/s. The correlation coefficient between the measured flow velocities and the actual flow velocities is 0.992. When the blood flow orientation is not perpendicular to the direction of incident laser propagation direction, the ratios of the measured velocities of blood flow to the original ones are cosine to the tilted angle of sample.

Electrical characteristics of biological tissues are significant for early diagnosis of tumor tissues. Through detecting the Lorentz force effect of the samples, magneto-acousto-electrical tomography is confirmed to have ability to implement early diagnosis of tumor tissues with recognition of changes in electrical conductivity of organisms. In all previous work on magneto-acousto-electrical tomography, incident ultrasonic pulses are generated from conventional piezoelectric transducers. To avoid the electromagnetic interference to the ultrasonic excitation system, the piezoelectric transducer is required to be placed far away from the detected sample. However, the long distance of ultrasonic propagation between the ultrasonic transducer and the sample limits further clinical research. Firstly, laser-induced ultrasound transducers based on photoacoustic effect are proposed. The optic ultrasonic transducers are polymer-nanomaterial composites formed by carbon black and polydimethylsiloxane, which are promising to generate high-frequency and high-intensity ultrasonic signals through decreasing the thickness of composite films. The acoustic fields generated by optimized laser-induced ultrasound transducers are then characterized, and laser-induced ultrasound transducers are applied in the magneto-acousto-electrical tomography experiment. The results indicate that the output pressure and bandwidth of the ultrasonic signals generated by the laser-induced ultrasound transducers are similar to or better than those generated by the piezoelectric transducers. -6 dB frequency bandwidth and acoustic intensity of the laser-induced ultrasound transducers are measured to be about 7.5 MHz and 2.5 MPa, respectively. Due to the absence of electronics and metal in the laser-induced ultrasound transducers, acoustic sources generated by the laser-induced ultrasound transducers are compatible with magneto-acousto-electrical tomography and insensitive to electromagnetic interference.

The principle and design method of optical super-oscillation are introduced. A superoscillatory optical field with a local superresolution is experimentally obtained by pure amplitude-modulated spatial light modulator (SLM) and digital micro-mirror device (DMD). The experimental results show that the characteristic size of the superoscillatory field in the generated superresolution optical field is sixty percent of diffraction limit. The analysis of the spatial spectra used to validate the experimental results shows that the superoscillatory optical field does not generate spatial high frequency components beyond the diffraction limit.

Studying the transmission of light in biological tissues requires more accurate scattering phase function. It is necessary to study the effect of nucleus on the phase function. In this study, the Mie phase function, asymmetric factor g and second order parameter γ of monodisperse nucleated cells are modified based on the geometric scattering approximation theory, the effects of the morphological and optical parameters on the angular distribution of the Mie phase function and number of Airy peaks are analyzed. The variations of g and γ with wavelength, cell size, nucleus ratio and refractive index are numerically simulated. The results show that the distribution of the Mie phase function, number of Airy peaks, g and γ are not only related to the cell size, but also to the nucleus proportion and refractive index. The effect of intracellular optical structure cannot be ignored. Compared with HG phase function, the Mie phase function can describe the side-backscattering characteristics and calculate g and γ more accurately. The Mie phase function provides further theoretical support for studying label free cell detection methods and transmission characteristics of laser in biological tissues.

A method to improve the sensitivity of swept source optical coherence tomography (SSOCT) system is proposed. In the SSOCT system, when the splitting ratio of the coupler before the balanced detector, is not 50%∶50%, the DC bias in the detected interference signal will affect the sensitivity of the system. In this study, the influence of the splitting ratio of the coupler on the sensitivity is theoretically analyzed when the DC bias is introduced into interference signal, and it is proved that the sensitivity can be improved by the method of adjusting the splitting ratio and increasing the reference arm′s energy. Based on the parameters of the devices of the SSOCT system in the experiment, the sensitivity of the system is numerically simulated. The numerical simulation results prove the effectiveness of the proposed method, and the experimental results show that the sensitivity is improved by 2.3 dB after the proposed method is applied.

The diffuse reflectance of single-fiber reflectance probe is studied with the Monte Carlo simulation, and we find that the sub-diffuse scattering light is sensitive to the scattering phase function (SPF) related to tissue microstructure. A semi-empirical diffuse reflection model for small aperture measurement is studied, and the influences of second-order and third-order optic parameters on this model are analyzed. It shows that the two parameters have contrary effects on diffuse reflectance, and both effects are non-negligible for optically anisotropic biological tissues. A simplified semi-empirical model and its application condition are given, which provides potentially applicable support for measurement of tissue scattering properties and associated microstructure.

The finite element model for human lumbar spinal L3-L4 is described by three-dimensional reconstruction method-marching cubes (MC). With some vital soft tissues on spine, such as anterior ligament, opisthodetic ligament, yellow ligament and fiber ring added, the complete three-dimensional finite element model of spine is rebuilt precisely. Then the finite element model is divided into mesh and the corresponding material properties of all parts are set. Finally, load and boundary conditions with different directions are defined to simulate the stress and displacement of normal model and intervertebral disc swelling degeneration model under different conditions. Which can provide biomechanical basis on the clinical diagnosis and treatment of intervertebral disc bulge and intervertebral disc protrusion by analyzing its biomechanical properties.

Metal-enhanced fluorescence (MEF) theory is a hot research topic in recent years. In this study, the fluorescence intensity and photon dynamic treatment (PDT) enhancement of gold nanobipyramids (Au NBPs) with different aspect ratios (3.1-6.5) to photosensitizer AlPcS is quantitively analyzed using spectral measurement, cell confocal imaging and flow cytometry method (FCM). The results of flourscence spectrum and confocal imaging show that Au NBPs with high aspect ratios can greatly enhance the fluorescence intensity of AlPcS, and the maximum enhancement factor is 6. Au NBPs with low aspect ratio can greatly reduce the fluorescence intensity of AlPcS, because its plasma resonance band is close to the fluorescence band of AlPcS. Hela cells (human epithelial cervical cancer cells) apoptosis measurements show that the join of Au NBPs, especially Au NBPs with high aspect ratios, improves drug-loading rate and singlet oxygen production of AlPcS. Then the survival rate of Hela cell is reduced and PDT effect of AlPcS is enhanced. These results provide a new avenue for the research of surface-enhancement fluorescence and expand the bioapplications of metal nanoparticles.

In order to improve the speed of super-resolution optical fluctuation imaging(SOFI) method, a modified SOFI algorithm is combined with light sheet fluorescence microscopy (LSFM). Two wavelet-based filters are utilized separately in the temporal and spatial domains to eliminate the low-frequency background noise and readout noise of the raw image, which successfully reduces the image amount that SOFI needs. And it is used to process 50 frames of raw images of quantum dot and zebrafish, respectively. The result shows that introducing improved SOFI algorithm can improve the lateral resolution of a LSFM two times without changing the optical structure, which can be expanded to the biological research of living samples and overcome the limitations of numerical aperture of objective lens for LSFM.

A new algorithm of k-clock delay correction for swept source optical coherence tomography is proposed. The algorithm is based on cross correlation operation and can effectively correct the delay of the swept source k-clock signal. Due to the instability of the swept source and the external environment, as well as lack of precision of the synchronous trigger hardware, the k-clock signal of the swept source may have an uncertain delay with the interference signal when resampling the interference signal, resulting in decreased system resolution. A standard k-clock signal is acquired by experiments, and then the delay of the k-clock signal is calculated using the cross correlation operation. According to the calculated delay, the k-clock signal is shifted left or right to correct the difference with the standard k-clock, and then the corrected k-clock signal is used to resample the interference signal at evenly wavenumber domain interval. The experimental results show that the system performance is improved. The average running time of the algorithm is 0.18 s, and the resolution of the system is improved by 18.2%.

To find out the role of laser parameters on in-vitro tissue bonding, experiments are designed to study the effect of laser parameters, such as power and scanning mode, on the appearance and tensile strength of in-vitro skin tissue incision, and then the process parameters are optimized. Results show that the appearance and tensile strength of tissue incision is better and greater when we use low laser power with long welding time, and also the irreversible thermal damage decreases. Using interval laser scanning increases the bioactivity closed to the incision and decreases the thermal damage. Experiments are performed to verify the reliability and stability of the optimized parameters, and the tensile strength of incision is tested. Results show that the bonding along the depth of tissue can be realized and no carbide or burning occurs. Compared with that of the continuous laser welding process, the welding time is decreased by 30%-40%, and the tensile strength of incision is 0.38 MPa, which can meet the requirement.

We investigated the dose-effect relationship of photosensitizer ZnPc in photodynamic therapy (ZnPc-PDT) in killing the U87 MG cells and provided reference for rational administration of ZnPc. The proliferation of U87 MG cells was determined by MTT (thiazolyl blue tetrazolium bromide) tests. The effect of ZnPc concentration, laser power density, exposure time, oxygen content and tissue thickness on the proliferation was investigated. Then the production of singlet oxygen during ZnPc-PDT was determined by the DPBF probe and DCFH-DA reactive oxygen species assay kit. The cell morphology and the proportion of cell death was observed by an inverted microscope. The results show that U87 MG cell viability changes different parameters setting after ZnPc-PDT, and we can get a good ZnPc-PDT effect by adjusting the parameters.

An intravascular optical coherence tomographic (IV-OCT) system is developed, in which the diameter at the tip of the catheter probe is only 1 mm. In order to ensure the central axes of the Grin lens and the right angle prism attached to the micro motor shaft are aligned, a size-matching plastic sheath is designed to wrap the Grin lens. Then the Grin lens with the plastic sheath and the right angle prism are installed into a polytetrafluoroethylene (PTFE) sheath to assemble the probe, which has 1 mm diameter at the tip. A hardware filter is applied to removing the direct current component and the harmonic component in the k-clock signal generated by the swept laser source, and the resolution of the system is improved. The filtered k-clock signal is used as a trigger signal to resample the interference signal in the uniform k-space. Windowing, Fast Fourier Transform (FFT), logarithm, and background removal are applied to the resampled signal to get the A-scan data. At last, the coordinate transformation is applied to the A-scan data to reconstruct the circular display sample image. The axial resolution and the lateral resolution are 11.8 μm and 24 μm, respectively in actual measurement. The system imaging frame rate is 30 frame/s. With the proposed IV-OCT system, images of tubular white tape sample, shallot leaf, lotus root, and in vitro duck blood vessels are obtained.

To study the scattering characteristics of leukocytes at polarized light incidence, we modify Stokes-Müller matrix elements for polarized light propagation by using the geometric optics approximation theory. On the basis of eccentric sphere model, we numerically simulate the scattering light intensity spatial distribution of the mitochondria free leukocytes with different shapes, sizes and refractive indices with two polarized beams incident, and polarization directions of the two beams are perpendicular to each other. The relationship between the scattering characteristic and cell structure parameters, such as shape, size, and refractive index, is numerically simulated. The three-dimensional distribution of polarized light scattering shows different fringe features under different conditions, which illustrates that the distribution is relevant to physical parameters and optical parameters. The analysis of differences, ratios, and ratios of difference to sum of the scattering intensity shows that the backscattering of the polarized light can reflect rich structural information and optical information in the cell.

Tissue optical clearing technique combined with two-photon microscopy (TPM) can improve the imaging depth of biological samples. However, the refractive index mismatch between objective medium and optical clearing agent will cause spherical aberration which degrades the fluorescence intensity and axial resolution. To solve this problem, we analyzed the effect of SA at the focus, and built a spherical aberration compensation model based on objective characteristics (numerical aperture and immersion media), the imaging depth and the sample refractive index. Then, we corrected the spherical aberration by incorporating a spatial light modulator into the TPM system. The TPM images of fluorescent bead phantom and optical clearing brain tissues show considerable improvement of fluorescence intensity and axial resolution. The proposed correction process is simple and fast since it does not require repeated imaging. More importantly, it is suitable for different objectives and optical clearing agents.

A highly-sensitive pharmacokinetic diffuse fluorescence tomographic system is proposed to achieve the indocyanine green (ICG) pharmacokinetic imaging of small animals. The system employs a photon-counting technique based on discrete optical fiber measurement of computed tomography scanning mode in the computer tomography, which effectively improves spatial sampling resolution of the system on the premise of high sensitivity and wide dynamic measurement range. Meanwhile, it adopts serial-parallel mixed measurement mode through switching four photomultiplier tube photon-counting channels by optical switch to obtain a balance between time resolution of measurement and cost-effectiveness of the system. We investigate the principle validity of the system by designing a dynamic phantom that can simulate ICG metabolism in living tissue. In addition, combined with the algorithm of fluorescent agent pharmacokinetic imaging developed by our laboratory, the reconstruction of ICG metabolic velocity is realized. Experimental results show that the proposed system has high sensitivity, spatial resolution and quantitativeness.

Skin cholesterol is a novel biomarker to assess the risk of atherosclerotic diseases. A system based on diffuse reflectance spectroscopy technology is designed for noninvasive and rapid detection of skin cholesterol. The feasibility of the system is validated through detecting digitonin-horseradish peroxidase copolymer solution which simulates the skin cholesterol of gradient concentration and skin cholesterol in vivo of subjects. A parameter S based on the relative diffuse reflectance increases linearly with the increasing concentration of the copolymer solution in the wavelength band from 440 nm to 550 nm (correlation coefficient r=0.992, P<0.01). After adjusting age, gender and other factors, it shows significant positive correlation between the skin cholesterol test results of subjects and the total cholesterol, low density lipoprotein cholesterol, and the correlation coefficients are 0.837 (P<0.01) and 0.778 (P<0.01), respectively. The diffuse reflectance spectroscopy is a noninvasive and convenient method for the detection of skin cholesterol, and the noninvasive detection of skin cholesterol in vivo contributes to the early detection of atherosclerotic diseases.

The aim of this study is to optimize the robustness and controllability of the 3D printed hydrogel scaffolds by iteratively reducing the mismatch between the designed and the as-printed. A feedback loop approach based on optical coherence tomography (OCT) in vivo online quantitative evaluation was performed for twice. The experimental results show that OCT has quantitatively characterized the morphological parameters, and the difference correlation analysis based on the characterization of OCT feedback controls the 3D printing process and enables decrease of the mismatch. The mismatch of the averaged pore size of the hydrogel scaffolds has decreased from 30% to 2%. It concludes that OCT can further expand its applications in the field of tissue engineering, and may be a key tool for scaffold design and characterization, 3D bio-printing process control, and so on.

In order to reduce the influence of absorption and scattering on tissue fluorescence spectra, the tissue fluorescence and diffuse reflection are simulated under different optical parameters with the Monte Carlo (MC) method, and a fluorescence recovery algorithm based on the tissue diffuse reflection spectrum is proposed. The empirical parameters in the proposed algorithm are coded as a particle in the solution domain, the classification performance is defined as fitness, and then a particle swarm optimization (PSO) algorithm is established to optimize empirical parameters. Skin fluorescence and diffuse reflection spectra of 327 subjects are collected with a tissue detection system for noninvasive screening of diabetes. The fluorescence spectra are recovered by the empirical approach, and the fluorescence intensity before and after recovery is selected as the input variable for the receiver operating characteristic (ROC) curve analysis, which is applied to evaluating the classification performance in diabetes screening. The sensitivity and specificity are 32% and 76% respectively, and the area under the ROC curve is 0.54 when the spectra before recovery are used, while the sensitivity and specificity are 72% and 86% respectively, and the area under the ROC curve is 0.86 when the spectra after recovery are used. The results indicate that using the tissue fluorescence spectrum recovery algorithm based on PSO can improve the application of tissue fluorescence spectroscopy effectively.

Optical coherence tomography (OCT) is a non-invasive high resolution cross-sectional imaging method with high sensitivity. A simple handheld spectral- domain optical coherence tomography (SDOCT) system is developed for imaging tooth tissues. The design of the handheld OCT probe is described in detail, and the lateral scanning is realized by using a scanning mirror. The handheld OCT probe is characterized by its compact size and portable feature, making it easier for in vivo tooth imaging. The system is used for imaging of in vitro and in vivo tooth tissues. The enamel, dentin and the interface between them can be clearly observed in the high-resolution tomographic images.

Imaging depth of acoustic resolution photoacoustic microscopy is capable of reaching the centimeter level. There are several drawbacks regarding to the mainstream illumination designs of current acoustic resolution photoacoustic microscopy systems, e.g. switch between bright field illumination and dark field illumination is not available, and the utilization efficiency of laser energy is very low. Therefore, the application of the system is limited. A novel optical illumination design has been proposed to overcome these limitations. A convex lens is applied to focus the diverging ring-shape light before it is reflected by the optical condenser, as a result, the ultimate laser spot on the sample surface can be smaller. The Monte Carlo simulation results show that laser fluence within the volume of effective ultrasound detection has been improved by as much as 6 times, and therefore the intensity of photoacoustic signals can be linearly increased as well. On the other hand, the tuning range of optical focus depth of the system has also been expanded, and after specific tuning, optimal photoacoustic signals can be obtained within different kinds of samples.

A preliminary research of noninvasive monitoring of blood glucose concentration is performed using the photoacoustic detection technique, and a noninvasive photoacoustic detection system is established. A tunable pulsed laser is used as the excitation source and a confocal ultrasonic transducer is used to capture the photoacoustic signal of glucose concentrations. The pre-amplifier, data transmission based on GPIB-USB bus and virtual instruments developing software LabVIEW are used in this system. The time-resolved photoacoustic signals for the glucose solutions with concentration from 0 mg/dL to 300 mg/dL are acquired based on the established photoacoustic detection system. The glucose solutions with different concentrations are scanned by the tunable pulsed laser with output wavelength from 1300 nm to 2300 nm and with interval of 10 nm, and the photoacoustic peak-to-peak values are obtained. In order to obtain the characteristic wavelengths of the glucose solution, the difference spectrum algorithm and the first order differential derivative are used. The mathematical correction model between glucose concentrations and photoacoustic peak-to-peak values is established by means of linear least square fitting algorithm for the optimized characteristic wavelengths, and the glucose concentrations are inverted. Two better characteristic wavelengths are chosen based on the minimum root mean square error.

Ten different morphological distributions of melanin were proposed according to their formation and migration characteristics, and the two-scale skin model was applied to investigate the influence of melanin distribution, pulse duration, diameter and depth of pathological vessels on the radiant exposure thresholds of epidermis and blood vessels during the laser therapy of Port Wine Stains. The results show that distribution of melanin has a greater influence on the epidermal radiant exposure threshold, but has no obvious effect on that of blood vessels. It is conducive to cure vascular skin diseases with more uniform distribution of melanin, smaller and shallower blood vessels. Spray duration should be prolonged when melanin only distributes in the basal layer of epidermis. With optimized curative effect for vascular skin diseases, long laser pulse (15-20 ms) will be a good choice for more uniform distribution of melanin and larger blood vessels, which is close to the thermal relaxation time of pathological vessels. Shoter pulse (<5 ms) should be chosen for smaller and deeper vessels.

In order to study the optical clearing effect on reducing the skin scattering and increasing the laser energy reaching the target vessel, a quantitative study on the optical clearing effect of glycerol on the skin tissue phantom was conducted in the visible to infrared wavelength band. An in vitro experimental system for laser treatment of port wine stain was set up to obtain quantitative relationship between optical clearing effect and the blood coagulation properties under the irradiation of multi-pulse Nd∶YAG laser. The results show that the diffuse reflectance of the skin tissue phantom decreases by 36.69% and the transmittance increases by 38.73% at 1064 nm after 0.5 mL anhydrous glycerol is applied on the skin phantom surface for 10 min. After 0.5 mL anhydrous glycerol is applied on the skin tissue phantom surface for 4 min, the number of laser pulses required for blood coagulation decreases by 25%. After application for 10 min, the number of laser pulses required for blood coagulation does not decrease further, but the blood coagulation area increases by 34.1% compared with that after 4 min. The results indicate that glycerol is effective to improve the laser treatment of port wine stain by increasing the laser energy reaching the target vessel.

Terahertz (THz) radiation lies between the infrared and microwave regions of the electromagnetic spectrum. Because of organisms’ unique response to the THz wave, THz wave applications in biomedical research, especially in its interactions with biological tissues become a hot spot. Whether the THz wave has the photodynamic effect by exciting the photosensitizer is explored in the study. The wide spectrum (1-3 THz) of pulse terahertz is used as a light source to excite the photosensitizer-hematoporphyrin monomethyl ether (HMME) for 30 min, and then DPBF is used as singlet oxygen scavenger to test the yield of singlet oxygen. HepG2 cells in conventional culture are illuminated with the same dose of terahertz wave, the cell morphology is observed by an optical microscope, the cell activity is determined by MTT method. The singlet oxygen production in PS+THz group is significantly higher than that of pure THz wave irradiation (21.04% vs. 2.39%). Compared to control cells, HepG2 cells in PS+THz group are slightly rounded and have a tendency to shrink. The activity of HepG2 cells incubated in HMME (HMME+THz group) is reduced to 81.13% after irradiation by THz wave (99.21% in THz group). The experimental results show that the THz wave of wide spectrum (1-3 THz) and nanojoule energy can excite the photosensitizer of HMME with excitation efficiency of about 20%.

Free-running holmium∶YAG lasers transmitting in a fiber with core diameter of 800 mm can induce vaporization bubble explosively at the end of fiber underwater. Shock waves will be produced upon the vaporization bubble collapse. The shape and dynamic state of vaporization bubble under different laser parameters, can result in variable parameters of the number, intensity, oscillation period, acoustic frequency, and so on, of shock waves. An acoustic measurement system has been built to investigate the influence of pulse duration on acoustic transients, and the characteristic parameters of the first acoustic transient can be recorded by an oscillograph. The experimental results indicate that under the condition of 1000 V voltage, 5 Hz frequency, 0.7~1.6 ms pulse duration of pump power, resonance will happen for the intensity of acoustic transients at the starting period. Finally the intensity will decrease after reaching the peak value of 1.01 MPa. The frequency of acoustic transients will always decrease gradually as the pulse duration of lasers increases, and its peak value can reach 400 Hz. Holmium∶YAG lasers with higher energy and shorter pulse duration can induce acoustic transients with higher intensity, more number, shorter period, and higher frequency.

Real-time tracking for surgical instruments is required in modern inversion endoscope surgery. Compared with traditional tracking methods, the surgical navigation method based on inertial sensing can effectively avoid the limited tracking region caused by optical tracking (OPT), and overcome high sensitivity to magnetic disturbance in electromagnetic tracking (EMT). Meanwhile, the effect from the sensors’interference in both of orientation estimate and position determination is considered and the anti-interference technique achieving more stable output is improved. The experimental results show that even under magnetic disturbance, the orientation error is less than 3° and position error is less than 4 mm. Both of them meet the requirements of clinical applications.

The Monte Carlo (MC) method is widely used in simulating light propagation in skin tissues. A tetrahedron-based Monte Carlo (TMC) method is developed. Energy deposition error due to numerical dissipation can be avoided by the definition of distance threshold. Laser propagation in a two-layered skin model with single blood vessel is simulated to compare geometry-based MC (GMC), voxel-based MC (VMC) and TMC. In GMC, the interface is defined mathematically without any discretization. It is the most accurate but not applicable to more complicated domains. The implement of VMC is simple but it may lead to non- neglected error due to zigzag polygonal interface. TMC provides balance between accuracy and flexibility in the treatment of photon-boundary interaction by the boundary adaptive tetrahedron cells. Numerical results reveal that space adaptability of geometrical shape of TMC is much stronger than that of VMC. Photon energy deposition error by TMC in complex interfacial region is 10%~25% of that by VMC. These results show that TMC is superior in the discretization of tissue boundaries.

Optical diffuse spectroscopy is crucial in quick and non-invasive measurement of biological tissues. However, the lack of exact analytical solution limits its applications. A semi-empirical formula of diffuse reflectance measured via small apertures is elaborated on the basis of Monte Carlo method, and a function relation between the reflectivity and the aperture, relative refractive index is created. Based on this semi-empirical formula, the inversion of optical parameters of turbid biological media is performed and its application range is analyzed. Compared to the expression of diffusion approximation, the proposed analytical formula is mathematically simple and suitable for the measurement of radiation field near the light source.

Ultrasound-modulated optical tomography (UOT) has high spatial resolution of ultrasonic location and high sensitivity of optical detection. Both of scattering objects and absorption objects can be imaged by UOT. The signal to noise ratio and image contrast of UOT is improved by laying two apertures between the sample and the detector (photomultiplier tube, PMT) and choosing appropriate position of PMT. One dimensional imaging of scattering objects and absorption objects buried in turbid media is provided. The experimental results indicate that the relationship between modulation depth of ultrasound-modulated signal and the scattering and absorption properties of media is dependent on detection position of PMT. The scattering objects and absorption objects are imaged simultaneously and distinguishable when PMT is at an appropriate position.

In the swept source optical coherence tomography (SS-OCT) instruments, an unfixed delay between the spectral calibration signal k-clock and the OCT signal makes the result of spectral calibration incorrectly, which reduces the imaging resolution. An automatic delay correction algorithm is proposed to automatically correct the delay between k-clock signal and OCT signal accurately. The algorithm based on the proposed average peak method and average full width at half maximum (FWHM) method, through processing and analyzing the OCT signal, divides into coarse adjustment, fine adjustment and accurate adjustment to search for delay point automatically. According to the search result, the delay time is corrected. After delay correction, high resolution reconstructed image is realized through spectral calibration of OCT signal evenly distributes in the wave-number (k) space. Experimental results show that, the imaging resolution improves 60% by correcting the delay automatically, which proves the effectiveness of the proposed algorithm.

A three-dimensional geometric Monte Carlo (GMC) method is proposed. By taking advantage of the geometrical relationship between the photon position and the interface, GMC can simulate the photon transportation in the whole domain rather than a voxel. Discrete voxels are unnecessary and the photon motion is calculated according to the geometrical optics. Therefore the optical transmission error induced by the voxel Monte Carlo (VMC) method can be eliminated. Also, the computation time consumed by GMC is dramatically shortened, and GMC is about 25 times faster than VMC with voxel grid size of 10 microns for the single vessel situation. Through the calculation of the energy deposition in a tissue model with the multi-coaxial vessel cluster, it is found that the dependence of energy absorption on the vessel distribution will recede when the vessel number increases at a certain blood volume fraction (BVF). The largest deviation of blood energy absorption is 4% with 20 vessels when BVF is 5%. This implies that artificial vascular distribution can be used to predict the real absorption characteristics with the same blood volume fraction instead of difficult measurement of real complex distribution of blood vessels, which is of great practical importance for the clinical treatment.

A 1940 nm and 980 nm laser pain stimulus system is built to explore the effect of baseline temperature control, oxyhemoglobin solution and laser irradiation area control on laser pain stimulus. With pig skin, a thermocouple module is used to monitor the change of the skin temperature under baseline temperature control and 20% oxyhemoglobin solution; the shape and size of the light is controlled with the help of filters. By using the 1940 nm laser control of baseline temperature of 40 ℃ is realized and joint pain stimulus experiment is carried out with the help of the 980 nm laser. Surface temperature drop time under the condition of 20% oxyhemoglobin solution (110 ms) is much lower than the blank control (1.2 s) and air cooling heat dissipation (341 ms), proving that this is an ideal method to improve pain signal quality. Temperature field distribution with three different filters is listed, proving that the shape and size of the pain stimulus is controllable. The three technologies in the dual-wavelength pain stimulus mode mentioned above can improve the result of the laser pain stimulus and prove the feasibility and credibility of this system.

Previous studies and current clinical practices have applied laser therapy without effective feedback and guidance, resulting in highly variable outcomes. A method of integrating laser therapy and sweptsource optical coherence tomography (OCT) is presented to implement real-time monitoring of tissue thermal interaction process. OCT interference spectral signals are continuously acquired in M-mode fashion without translating the skin sample, yielding depth-resolved measurement of the same axial line as a function of time during laser exposure. Thermal injury evolution is monitored quantitatively in real time through analysis of the measured complex reflectivity, in which variations in the magnitude and changes in the phase of the complex reflectivity are extracted to detect the overall aggregate changes of the scattering centers and measure the displacement in the axial direction. Meanwhile, attenuation coefficient is obtained to determine the extent of tissue thermal damage based on OCT scattering model. The experiment results indicate that thermal coagulation and necrosis occurs under irradiation of a certain laser power with the time lasting. During the process, the thermal injury boundary propagates downward monotonically and the optical attenuation coefficient nonlinearly increases. The demonstrated correspondence with microscopy and histologically determined injury depth and magnitude suggests that these techniques may enable precise monitoring and mapping of laser thermal therapy.

A novel full-field optical coherence tomography (FFOCT) system with low cost and high resolution is developed for imaging of cells and tissues. Different from other FFOCT systems illuminated with optical fiber bundle, the improved Khler illumination arrangement with a halogen lamp is used in the proposed FFOCT system. High numerical aperture microscopic objectives are used for imaging and a piezoelectric ceramic transducer (PZT) is used for phase-shifting. En-face tomographic images can be obtained by applying the five-step phase-shifting algorithm to a series of interferometric images which are recorded by a smart charge coupled device (CCD) camera. Three-dimensional images can be generated from these tomographic images. Imaging of the chip of Intel Pentium 4 processor demonstrats the ultrahigh resolution of the system (lateral resolution 0.8 μm), approaching the theoretical resolution 0.7 μm×0.5 μm (lateral×axial). En-face images of cells of onion surface and potted plant leaves cells show the excellent performance of the system for generating en-face images of biological tissues. The system is characterized by its high resolution, low cost and simple arrangement for adjustment, providing a practical method of performing FFOCT imaging.

In order to investigate the influence of photosynthesis on rice flag under enhanced UV-B radiation and He-Ne laser. He-Ne laser (5 mW·mm-2) irradiation and enhanced UV-B (13.08 kJ·m-2·d-1) radiation were used, the chlorophyll content and Rubisco of rice seedling leaves, chlorophyll fluorescence parameters about plant photosystem II (PSII) are measured. The results show that, after UV-B treatment, the chlorophyll content in rice leaves, and fluorescence parameters (other than qN) is lower than the control group (CK) and has significant differences (P0.05), fluorescence parameters does not change significantly (P>0.05). Compared with the control group (P<0.05), groups treated with He-Ne laser and UV-B, chlorophyll content, rubisco, and fluorescence parameters (except for qN ) of the rice leaves are higher than UV-B treated group. UV-B radiation on rice seedlings has injury to PSII, and a certain dose of He-Ne laser can improve the photosynthetic efficiency of rice. He-Ne laser can repair damage of enhanced UV-B to rice.

The self-developed high-speed three-dimensional swept optical coherence tomography (SS-OCT) system is reported. Based on fast swept laser technology, the system can realize high speed axial scan (A-scan) rate of 50 KHz. In order to shorten the development cycle, the system software is based on LabVIEW combining with Matlab. Which achieves modular design including timing control, data acquisition, data processing and image reconstruction. The system has a friendly interface and is easy to maintain. It utilizes an external clock uniform in K-space as triggers synchronously generated by the swept source—a K-trigger mode for data acquisition so that a uniform data sampling in K-space is enabled without any other linear wavenumber re-calibracation. Actually measured axial resolution of the system is 8.9 μm. The systerm sensitivity is experimentally determined to be above 100 dB in the whole depth range. This SS-OCT systerm is capable of realtime display of two-dimensional OCT and can obtain three-dimensional OCT with a measurement time of 1.8 s. Vivo human finger segments and apple peel tissue are investigated two- and three-dimensionally. The three-dimensional OCT volumes chearly show the structures of the fingerprint which are difficult to be observed in two-dimensional OCT images.

The targeted imaging of quantum dot (QD) conjugated cyclo (Arg-Gly-Asp-D-Phe-Lys ) peptides [c(RGDfK), QD-RGD] for laryngeal cancer blood vessel in vivo is studied. QD is conjugated with c(RGDfK) peptides by the reaction of carboxyl and amino groups. The spectra stabilities of QD-RGD in RMPI1640 and mouse serum are measured by fluorescence spectrophotometer. The targeting of QD-RGD to αvβ3 on Hep-2 and MCF-7 cells is studied by fluorescent microscope. Finally, the targeting of QD-RGD to laryngeal cancer vascular in dorsal skin fold window chamber by tail intravenous injection is investigated. The result shows that the spectra stability of QD-RGD in RPMI1640 does not obviously change in 4 hours. The fluorescence intensity of QD-RGD in mouse serum in 24 hours only decreases by 20%.The result of cells fluorescence imaging shows that QD-RGD can specifically bind to integrin αvβ3 on cells. The result of vascular imaging shows QD-RGD gathers in cancer blood vessel after injecting for 2 hours, and QD-RGD is removed from cancer blood vessel after 24 hours. The study demonstrates that QD-RGD can be used to targeted image cancer blood vessel in vivo, which offers a reference for studying targeting diagnosis and targeting therapy of laryngocarcinoma in vivo.

The transmembrane transport and distribution characteristics of emodin-β-CD inclusion complex in the nasopharyngeal carcinoma CNE-1 cells are observed using laser scanning confocal microscope. The results show that both emodin and emodin-β-CD inclusion complex are mainly distributed in the cytoplasm in granules. In the concentration range of 5~40 mg·L-1, the intake of emodin-β-CD inclusion complex nonlinearly increases with the increase of concentrations. Compared with the control group, emodin-β-CD inclusion complex uptake in cells is significantly lower than that of treatment with NaN3 and mannitol. After treatment with P-glycoprotein inhibitors cyclosporin A (CsA), intake of emodin-β-CD inclusion complex at low concentrations (smaller than 5 mg·L-1) significantly increases, but at high concentrations, intake of emodin-β-CD inclusion complex significantly decreases. Emodin-β-CD inclusion complex has long time of maintaining high concentration in cell relative to emodin. The mechanism of emodin-β-CD inclusion complex uptake in cells may involve energy-dependent endocytosis and P-glycoproteins participates in the conveying process of emodin-β-CD inclusion complex in CNE-1 cells. It provides a reference to improving emodin formulations.

We study the impact of laser acupuncture with different methods and parameters on type-II collagen-induced arthritis (CIA) model rat serum interleukin-1β (IL-1β), interleukin-15 (IL-15), interleukin-17 (IL-17), tumor necrosis factor α (TNF-α), vascular endothelial growth factor (VEGF) and cortisol (COR). The rats are randomly divided into model group, medication group, acupuncture group, deep laser acupuncture 1 mW group, 5 mW group, 10 mW group, the surface laser acupuncture 50 mW group, 100 mW group, 150 mW group, and normal control group is set, selecting Zusanli and Shenshu as acupuncture points. Samples are selected after 10 days of treatment. We use double-antibody enzyme-linked immunosorbent sandwich assay (ELISA) to measure serum cytokine level. Serum IL-1β, IL-15, IL-17, TNF-α and VEGF in the model group are significantly higher than those in the normal group (all P0.05); serum IL-17 level is the highest in the deep laser acupuncture 1 mW group and the lowest in the surface laser acupuncture 100 mW group, and the difference is statistical (P<0.001); serum TNF-α level is the highest in deep laser acupuncture 1 mW group and the lowest in drug group, and the difference is statistical (P<0.001); serum VEGF level is the highest in deep laser acupuncture 50 mW group and the lowest in the deep laser acupuncture 5 mW group, and the difference is statistical (P<0.05); serum COR level is the lowest in the acupuncture group, and the highest in surface laser acupuncture 150 mW group, the difference is statistical (P<0.001). Laser acupuncture can effectively reduce CIA rat serum proinflammatory cytokines levels such as IL-1β, IL-15, IL-17, TNF-α and VEGF, increase serum anti-inflammatory cytokines levels such as COR, and its effect is related with action mode of laser acupuncture and parameter settings.

Recently, laser therapy has been widely used for treating portwine stain (PWS) and other vascular lesions. However, the mechanism of the vascular injury during the treatment process is still not clear. In this paper, a hamster dorsal window chamber model is constructed to investigate the dynamic change of the vessel during pulsed laser treatment. A CCD camera and microscope are used to capture the dynamic variation of microvessels after 1064 nm laser pulse exposures. Experimental results show that the vessel continues expansion with the increasing of the radiant exposure, and vasoconstriction appears when the energy accumulates to a certain value with a single laser pulse. After multiple laser pulse irradiation, vessel expansion, blood coagulation and vasoconstriction are observed. These results may provide useful feedback for the treatment of PWS by near-infrared long wave laser.

Spinal cord injury (SCI) model is created by Allen′s method, and this study is designed to explore the effect of 810 nm low-level laser irradiation on expressions of TNF-α, IL-6 and IL-10 in acute spinal cord injury. 68 SD rats are randomly divided into normal group, SCI group and irradiation group. Light (810 nm, 150 mW) is applied transcutaneously at the lesion site of rats in irradiation group. Functional recovery is assessed by open-field test (BBB test) on 1 d, 3 d, 7 d after injury. The expressions of TNF-α, IL-6 and IL-10 in the injured spinal cords are examined by enzyme linked immuno sorbent assay (ELISA) method at the time of 1 h, 3 h, 6 h, 12 h, 1 d, 3 d, 5 d and 7 d after injury. We find that there is a statistically significant functional recovery (P<0.05) in the irradiation group compared to SCI group at 7 d. The expressions of TNF-α and IL-6 of irradiation group is significantly lower than the comparable SCI group at the time of 6 h, 12 h, 1 d (TNF-α) and 6 h, 12 h, 5 d (IL-6) (P<0.05). The expression of IL-10 of Laser group is significantly higher than the comparable SCI group at the time of 1 d, 3 d, 5 d and 7 d (P<0.05). There is no statistical difference at other time points. The results of our study show that laser irradiation can effectively inhibit the expression of pro-inflammatory cytokine TNF-α and IL-6 and significantly promote the expression of IL-10 in rats of acute spinal cord injuries, and laser irradiation can promote functional recovery of acute spinal cord injury rats.

A windowed Fourier transform (WFT) based method is proposed for extracting and compensating depth-resolved phase error in spectral domain optical coherence tomography (SDOCT) system. Firstly, by using a WFT to the interference spectrum of the light from the sample and the reference mirror, the depth-frequency distribution of A-scan of the sample is obtained. Due to the time-frequency characteristics of the WFT, the interference spectra corresponding to different interfaces at different depths are separated. The polynomial fitting for the phase variation of each complex interference spectrum is then performed and the phase errors distribution with the change of depth is obtained. Based on these phase errors, a precise numerical compensation for the phase is carried out. This method can not only be applied for extracting and compensating of depth-resolved dispersion phase error, but also can be used for depth-varied phase error compensation resulted from uneven spectrum sampling in wave-number space. A simulation for dispersion phase error extraction is conducted. Finally, the SDOCT images of the 4-layer cover glasses and fingernail of a volunteer are obtained and then used for phase error extraction with the WFT method. The results demonstrate that the proposed method has the capability of extracting the phase errors with high precision, leading to the improvement of the depth resolution and the image quality after phase error compensation.

A full-range Fourier domain Doppler optical coherence tomography (DOCT) system based on sinusoidal phase-modulating method is developed. The system combines Doppler detection with complex Fourier domain OCT. Full-range OCT and Doppler images are achieved using the complex spectral interferogram, which is retrieved based on the sinusoidal phase modulation B-M scanning and the combination of Fourier transform analysis and bandpass filter method. With the system, the depth imaging range is doubled and high velocity sensitivity is available in the whole B-scan image. Full-range OCT and full-range Doppler images of a flow phantom are achieved with the proposed system. The minimum detectable velocity of the system is investigated, which is 5.35 μm/s.

The aim of the present study is to examine whether low level Ga-Al-As laser irradiation has an effect on hedgehog signaling pathway during osteoblast proliferation in vitro. The molecular mechanism of how low level Ga-Al-As laser irradiation promotes bone formation is explored. This study provides a theoretical basis for the clinical application of low level Ga-Al-As laser irradiation in oral implant. Mouse osteoblastic cell line MC3T3-E1 is cultured in vitro. The cultures after laser irradiation are treated with recombinant N-terminals sonic hedgehog (N-Shh) or hedgehog inhibitor cyclopamine respectively. The experiment is divided into 4 groups. The proliferation activity is detected by cell counting, MTS, flow cytometry at 12, 24, 48, 72 h after laser irradiation. Proliferation activity of laser irradiation and N-Shh group is remarkably increased compared with those of laser irradiation group. Proliferation activity of laser irradiation and cyclopamine group is remarkably decreased compared with those of laser irradiation group, meanwhile proliferation activity of laser irradiation and cyclopamine group is remarkably increased compared with those of control group. These results suggest that low level Ga-Al-As laser irradiation activate hedgehog signaling pathway during osteoblast proliferation in vitro. hedgehog signaling pathway is one of the signaling pathways by which low level Ga-Al-As laser irradiation regulates osteoblast proliferation.

Mechanism of chemotherapeutics for tumor therapy is to restore infinite proliferous cancer cells to normal apoptosis, therefore, apoptosis monitoring has important guidance for clinical treatment. A novel and robust method for apoptosis monitoring of tumor cells is engineered based on dynamic laser tweezers, using SKOV3 cell line as typical sample. SKOV3 cells are cultured under four gradient concentrations of cisplatin, and trapping efficiency of four groups are measured by proposed system, which presents great advantages of celerity, low consumption, and label-free explorations for living cells without perturbing experimental conditions in combination with classical probes. The proposed technique has great potential in improving cancer treatment by monitoring the objective efficacy of tumor cell killing.

A compact optical-resolution photoacoustic microscopy system is designed with a pulsed laser diode, which has the properties of being low cost, small size, robust and high repetition frequency. Typical photoacoustic images of carbon fiber and blood vessel phantoms are reconstructed clearly. During the experiments, the pulsed laser diode excitation is droved to implement C-mode scanning excitation with three-dimensional translation stage, and the excited photoacoustic signal is captured by a 1-3 composite ultra-bandwidth ultrasonic transducer. The photoacoustic signal-to-noise ratio is recorded of approximate 11 dB, and the lateral resolution of the current system is improved up to 1.5 μm from 500 μm of the first-generation system. The experimental results demonstrate that the proposal method has the potential to be developed as a configuration of inexpensive, real-time, portable, and high-resolution photoacoustic microscopy technique.

The influence of laser irradiation on enzyme activity depends on the wavelength and energy of the light. The influence of wavelength and energy on enzyme activity is studied systematically, and whether laser and LED light sources have the same effect on enzyme activity is examined. Phospholipase C is exposed at 0~810 J/cm2 of lasers at the wavelength of 532, 808, 1064, 1342 nm and two LED sources at the wavelength of 640 nm and 810 nm respectively, and enzyme responses are evaluated by measuring ceramide concentration using high performance thin-layer chromatography (HPTLC) after irradiation of 0.5, 1, 2, 3, 4, 6, 17, 24 h. The duration of effect is evaluated from the experimental data. The enzyme activity can be increased by using either laser or LED source whose wavelength is located within a certain range, and the effect depends on the energy and wavelength of the light. The increase in enzyme activity continues for about 4 h after irradiation. The result shows that the duration of enzyme activity change should be included as one of the main laser parameters while reporting the effect of laser irradiation on enzymes. Besides, laser sources and LED sources have the same effect on enzyme activity with the same wavelength and absorbed energy.

The synthetic aperture (SA) imaging based on multi-images fusion is dynamically focused in both transinission and receiving yielding an improvement in resolution. But this imaging technique sets high demands on processing capabilities, data transport and storage. It also makes the implementation of a SA system very challenging and costly. The proposed method is specifically for this issue. The method uses the focused image lines as input data, and takes advantage of the synthetic aperture imaging based on multi-images fusion which picks out the coherent samples of the recorded echoes and sums these samples, thus obtaining a high resolution image. The proposed method is dynamically focused in both transmission and receiving, and a range independent lateral resolution is obtained. With Field II software, simulations on scatters and phantom are made and compared with broadband minimum variance (MV) beamforming and SA imaging based on multi-images fusion, the feasibility of the method named a fast synthetic aperture (FSA) imaging is verified.

A C-scanning photoacoustic imaging system is designed with a pulsed laser diode, which has the properties of low cost, small size, compact structure, and high repetition frequency. The 3D-visual reconstruction algorithm is employed to observe the 2D and 3D photoacoustic image. During the experiments, the laser diode and the ultrasonic transducer keep the fixed positions using a front side detection configuration. The experimental results show that lateral resolution of the imaging system is determined as 0.5 mm, and the speed of A-scanning is 0.16 s/div with a signal-to-noise ratio of 20.6 dB. The laser diode is only 10 cm×3 cm×3 cm with a pulse energy output as low as 14 μJ. The proposal method has the potential to be developed as a configuration of inexpensive, real-time, and portable noninvasive photoacoustic imaging system for biomedical tissue.

Q-switched Er:YAG laser and free-running Er:YAG laser are used to study the laser ablation for the fresh porcine thighbones tissue in vitro. The ablation threshold range of the Q-switched laser and the free-running laser are 1.80~2.40 J/cm2 and 3.46~5.00 J/cm2, respectively. The results indicates that the ablation threshold of the Q-switched laser is lower. The fresh porcine thighbones tissue in vitro is irradiated by the two laser modes under the conditions of repetitive rate of 3 Hz, pulse energy of 200 mJ, and pulse number of 15 times. In addition, the morphologic changes of the tissue crater are observed by a scanning electron microscope (SEM). The morphology and the microstructure of the incision surface of the tissue ablated by the two laser modes are compared. Meanwhile, in the process of laser ablation, temperature distribution of the irradiation region with the two lasers for the tissue is measured by thermal infrared imager. Results show that after laser ablation for the tissue by the Q-switched laser, the lancing is smooth and the thermal damage for the surrounding histocyte is slight. Thus, in the process of the laser ablation for the porcine thighbones tissue in vitro, the Q-switched laser has a significant advantage.

Diameter and depth of dilated blood vessels are two key parameters of port wine stain (PWS) lesions. Recently, optical coherence tomography (OCT) has demonstrated considerable promise for clinical test and the key parameters extraction of PWS. However, intensity attenuation in depth and speckle noise in OCT images constitute two primary limiting factors with respect to resolving the morphologic information of the PWS lesions. In order to enhance the visual quality of the OCT images, we develop new image speckle reduction algorithms for the OCT signal. In the study, epidermis segmentation is based on a dynamic programming scheme; according to the epidermal boundary curve as a baseline, the details in the deep are enhanced by the attenuation compensation. The visual inspection of the enhanced images is then improved by a new variation model that combines the regularization term with the statistical characteristic constraints (Rayleigh distribution) of data corrupted by OCT speckle noise to eliminate the corresponding multiplicative noise. The result shows that the proposed algorithm provides significant improvements of the edge information about the obtained PWS OCT images of dilated blood vessels, which is helpful to divide and extract the key parameters.

Full range optical coherence tomography (OCT) without additional group delay based on spatial carrier frequency is developed. A grating takes place of the mirror in the reference arm of the traditional OCT system and phase difference between adjacent A-scans without additional optical path difference is introduced by using phage modulation. Spatial interferograms is obtained from the detected OCT signal by the transverse Fourier transform and filtering. For filtering signal, an inverse Fourier transform is done. A full range OCT image can be obtained after axial Fourier transform. The theory and the system based on the spatial carrier frequency are introduced. The investigation on the image quality under different modulation frequencies is experimentally conducted. The full range OCT images of mirror and finger are presented.

A colloidal gold lateral flow (LF) strip reader based on CMOS image sensor, characterized by ultrasensitive and high repeatable, is developed. As gold nano-particles absorb green light strongly, green LEDs are used as the light source in the reader. In order to get the best illumination uniformity, gray value distribution of blank strip image is used to adjust the location and intensity of LEDs. CMOS control parameters are specified to get the most suitable image quality for image analyzing by self-defining parameters. Blank strip is used to calibrate the background signal. The quantitative result is derived from the ratio of integral reflection optical density of T line signal to C line signal. LF strips of cardiac troponin I (cTnI) with standard mass concentration gradients from 0.25 ng/ml to 64 ng/mL are detected. The 4-PL quantitative model is used to fitting standard working curve, whose correlation of coefficient (R2) is more than 0.99. The coefficient of variation (CV) of 20 times repetitive experiments of 0.25 ng/mL is 2.790%, and 64 ng/mL is 0.134%. The functional sensitivity (FS) is better than 0.25 ng/mL. The reader is sensitive, stable, simple, and suitable for field detection.

We investigate the killing effect of photodynamic therapy (PDT) induced by photocarcinorin (PsD007) on human epidermoid carcinoma Hep-2 in vitro, and explore the preliminary killing mechanism. Methyl thiazolyl tetrazolium (MTT) colorimetric assay is applied to measure the relative survival rate of PDT with different photosensitizer concentrations, light doses and antioxidants. Confocal microscope is used to observe the subcellular localization of PsD007. Annexin V/PI double staining is used to detect the apoptosis rate. DCFH-DA probe is used the to detect reactive oxygen species (ROS) production. The fatality rate of PDT on Hep-2 can be as high as 85.4%, and is positively correlated with photosensitizer concentration and energy density. Three kinds of antioxidants can all antagonize the damage effect induced by PDT in different degree, while sodium azide has the best effect. The fluorescence images of PsD007 subcellular localization demonstrate that PsD007 diffuses into the mitochondria. Two hours after PDT, the ROS production is as 2.71 times as control group. The apoptosis rate is up to 49.5% (energy density is 1.2 J/cm2) and 70.2% (energy density is 4.8 J/cm2) four hours after PDT. PsD007-PDT could significantly kill Hep-2 cells and induce apoptosis that mitochondria may be the initial target.

A graphics processing unit (GPU) accelerated Monte Carlo (MC) approach is developed for modeling photon migration in an arbitrarily complex turbid medium, where the diffusion equation (DE) might behave an ineffective modeling tool. Then an image reconstruction algorithm of time-domain fluorescence diffuse optical tomography is proposed based on the developed GPU-accelerated MC calculations, within the framework of the generalized pulse spectrum technique. Simulated results show that the MC-based approach retrieves on the position and shape of the targets in complexly structured domain that include low absorbing and high scattering, low absorbing and low scattering, high absorbing and low scattering, high absorbing and high scattering, and/or void regions, with higher accuracy than the DE-based one, demonstrating the improved generality of the proposed method.

This study investigates the toxicity of CdTe quantum dots (QDs) on mouse ovarian granulosa cells in vitro. The fluorescence stabilities of QDs in DMEM culture medium, M1640 culture medium and phosphate buffer solution (PBS) are measured by fluorometer, respectively. Apoptosis is observed by chromatin staining with Hoechst32258 and cell viability is detected by cell counting kit-8 (CCK-8) assay after the granulosa cells are treated with QDs. The results demonstrate that the fluorescence stability of QDs in DMEM culture medium is better than that in the other media, the QDs fluorescence emission spectrum in it does not shift and the intensity decreases only 9.8%. It is found that the apoptosis of granulosa cells treated with QDs is dosage-dependent by the Hochest32258 staining, which is confirmed by the CCK-8 assay. The research demonstrates that the QDs at lower concentration have not affected the morphology and function of granulosa cells in vitro. However, with the increase of accumulation of QDs inside cytoplasm, the apoptosis increases significantly. This study offers very useful information of reproductive toxicity of QDs to guide the safe application of QDs in vivo.

Taking the dentine as the research object, a method to solve the light diffusion properties of anisotropic biological tissue is proposed. The diffusion tensor is introduced into the diffusion equation to describe the light propagation inside the tissue. Through theoretical derivation and considering light diffusion results of isotropic cubic tissue models, it is proposed that the ratio of diffusion tensor component can be expressed by ratio of long and short axes of forescattering contour ellipse incident by point light source. The experiment is performed to measure the forescattering light intensity distribution of dentine slice from two different directions incident by point light source of 10 μm diameter. The experiment result reveals that the ratio of diffusion tensor component of dentine is DyyDzz:Dxx=7.491.31. The orthogonal anisotropic diffusion equation is solved by finite element analysis method using ANSYS software by setting parameters as the obtained results. The simulated results are compared with the experimental data, and the correctness is confirmed. The study can deepen the understanding of scattering properties of dental dentine and gives the reference for the early detection of dental caries based on scattering effect.

Compressive sensing (CS) theory is used in fluorescence microscopy imaging and a new microscopic imaging system is designed and implemented. A liquid crystal light valve is employed to calculate the linear projection of an image onto pseudorandom patterns. Fluorescence is collected on a point detector. Images of the samples are acquired combined with the reconstruction theory of CS. The number of samples is smaller than that imposed by the Nyquist-Shannon theorem. The system hardware is simple as scanning is unnecessary during the imaging process. Compared with the traditional spectral imaging modalities, such as using optical filter and raster scanning, this system only needs a spectrometer to acquire signal and then multispectral images are reconstructed from measurements corresponding to a set of sub-bands. As the fluorescence microscopy imaging suffers fluorescence decay during imaging process, in this experiment, data preprocessing such as intensity normalization is applied and the results indicate that the influence of fluorescence decay on reconstruction is eliminated effectively with this processing method.

Low-power laser irradiation (LPLI) can promote cell proliferation, migration and differentiation through activation of multiple signaling pathways. However, it is unclear whether LPLI can promote triglyceride biosynthesis in adipocytes via regulation of extracellular signal-regulated kinase (ERK) and protein kinase B (PKB, also named Akt). In the present study, the changes of the ERK and Akt activity in 3T3-L1 pre-adipocytes and mature adipocytes upon LPLI stimulations is investigated using western blot analysis. The findings indicate that the activity of ERK and Akt is significantly elevated in 3T3-L1 pre-adipocytes under LPLI treatment. In contrast, the activity of ERK is dramatically reduced in mature adipocytes, but the activity of Akt is significantly elevated under LPLI treatment, suggesting that LPLI can differentially regulate the activity of ERK and Akt. Furthermore, the concentration of triglyceride in insulin resistant adipocytes is increased which is induced by LPLI through inhibition of ERK and activation of Akt. These results imply that LPLI can improve lipid metabolic disorders-induced insulin resistance through regulation of ERK and Akt.

With imaging depth increasing, the local contrast in the optical coherence tomography (OCT) image of object decreases, which makes it difficult to observe the internal features of object. An adaptive multi-scale Retinex (AMSR) algorithm is proposed for OCT attenuation compensation. It automatically adjust the weights of Retinex enhanced images with different scales according to the mean values of absolute differences between Retinex enhanced image with large scale and Retinex enhanced images with other small scales. This method is verified by a human fingertip OCT image and skin OCT image that AMSR can effectively compensate the light attenuation in the original OCT image, and enhance the local contrast of structure details within object. Furthermore, comparing with the original OCT image, the visual contrast measure (VCM) of the AMSR enhanced image increases 5740. This method is useful to improve the visualization of structures inside object.

This paper describes a low noise optical coherence tomography (OCT) technology based on curvelet algorithm and a demarcating arm to decrease the speckle noise in OCT. The demarcating arm in the Michelson interferometer makes the precise positioning of A-scans possible and diminishes the displacement error caused by tissue moving. Besides, each A-scan is curvelet transformed and adaptive filtered, the curvelet coefficients are weighted, averaged and reconstructed to reduce speckle noise. Compared with traditional A-scans average method, the application of curvelet algorithm and demarcating arm in low noise OCT provides 18.35% increase in signal to noise ratio.

We synthesize CdTe quantum dots in aqueous solution and characterize the stability of quantum dots in different culture media and different pH environments. The impact of quantum dots on HeLa cellular proliferation inhibition rate is studied. The quantum dots conjugated with transferrin are used for HeLa cell labelling. Finally, the quantum dots are conjugated with dextran and applied in the transparent dorsal skin fold window chamber to observe the dynamics of the bioconjugations in blood vessels. The experimental results show that the quantum dots peaking at 660 nm are stable in cell culture media of DMEM and M1640. When the pH of the buffer solutions increases from 5 to 13, the fluorescence intensity of CdTe increases firstly and then reduces. The cell viability is higher than 80% even when the concentration of quantum dots is 13 μg/mL. The quantum dots conjugated with transferrin obviously target to the HeLa cells. What′s more, the clear dynamic flourescence images of quantum dots conjugated with dextran are observed under microscope. The study shows that such quantum dots can be used for living imaging research successfully.

Cross-polarized image can provide both polarization-sensitive information and a more clear sub-surface structure of the sample. As a result, getting the cross-polarized image by using optical coherence tomography (OCT) becomes more and more popular. A novel fiber-based cross-polarized optical coherence tomography (CP-OCT) system is implemented, which is capable of acquiring both cross-polarized signal and co-polarized signal of a sample simultaneously. Forming principles of both cross-polarized and co-polarized signals are described, and the expressions of them are derived using Jones matrix. The images of a glass slide, a λ/4 wave plate at a wavelength of 1310 nm, and vivo skin obtained with the system confirm that CP-OCT can provide both polarization-sensitive and polarization-insensitive informations of the sample.

The offline time-gated stimulated emission depletion (g-STED) microscopy, which is based on time-correlated single photon counting (TCSPC) algorithm, is proposed. As STED beam can eliminate the ratio of spontaneous fluorescent emission while reducing the fluorescence lifetime, the lifetime of fluorescent signals in the center of excitation focal spot and that in the surrounding doughnut area which are overlap by the STED focal spot are significant different. Based on this principle, in a general continuous wave STED (CW-STED), the fluorescent lifetimes of the whole imaging region are calculated by TCSPC, and the signals with shorter lifetime are discarded after all data recorded. The effective point spread function (PSF) of each fluorescent labels are shrinked in order to enhance the resolution. Compared with traditional ones, this offline g-STED not only decreases the incident intensity of laser to avoid the risk of fluorescence photobleaching and optical toxicity, but also increases the flexibility of time-gate manipulation. A spatial resolution of 80 nm is obtained in the experiment when only 45 mW STED beam is introduced. The potential influences of time-gate selection to the resolution and signal-to-noise ratio (SNR) are further discussed.

The effects of endogenous and exogenous nitric oxide on cancer cell mitochondrial membrane potential are studied by combining microplate fluorescence analyzer and special fluorescence probe rhodamine 123. Results show that the fluorescence intensity increases rapidly and keeps at a high level for a quite long period after nitric oxide donor is injected into the cells, while the fluorescence intensity of control group do not change significantly. Moreover, incubation with nitric oxide synthase inhibitor or nitric oxide donor for 24 hours prior rhodamine 123 loading can decrease or increase mitochondrial membrane potential, respectively. These results indicate that the increase of endogenous or exogenous nitric oxide can lift up the potential of mitochondrial membrane. It will be helpful to understand the role of nitric oxide in promoting cancer cell proliferation and metastasis at organelle level.

Laser ultrasonic technology, a noncontact nondestructive evaluation method, can be applied to evaluating the properties of human teeth. With a finite element method, this paper studies laser induced surface acoustic wave (LSAW) characteristics propagating in human teeth. Setting up a theory model for laser-introduced surface acoustic wave (SAW) propagating in human incisors, it discusses the temperature field induced by laser irradiate in dental surface, as well as the effects of inhomogeneous enamel and early dental caries (white spot lesion) on LSAWs. Studies in this letter can provide a theoretical basis for nondestructive evaluation of human teeth with laser ultrasonic technology.

Effects of 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) with low energy on intracranial angiogenesis and glioma growth are evaluated. Twenty seven nude mice are received low energy of ALA-PDT (ALA: 300 mg/kg, dose: 10 J/cm2) on the right side of the cerebral cortex. After 1、5、10 days, angiogenesis is evaluated by 2 and 3 dimensional vessel images, and expressions of VEGF and hypoxia-inducible factor-1α (HIF-1α) by western blot. Other 12 nude mice are divided into control and ALA-PDT (10 J/cm2) pretreated groups. Ten days after pretreatment, mice are implanted intracerebral U87 glioma; and tumor volume is calculated by H.E staining after 21 days. Results show that the vessels in the contralateral brain are as control. Both 2 and 3 dimensional vessel images shown that there is no difference in the microvessels morphology on the first and fifth days after ALA-PDT compared with control. However, there is angiogenesis on the tenth days showing as decreased length, increased diameter and the number of branch points. VEGF expression significantly increased on fifth day and becomes higher on the tenth days after ALA-PDT, although there is no change on the first day; while HIF-1α expressions increased on the first day and become higher and higher. ALA-PDT with low energy can induce VEGF expression and intracerebral angiogenesis mediated by HIF-1α, and this effect promotes glioma growth in brain.

A three-dimensional (3D) full-range complex Fourier domain optical coherence tomography (FDOCT) system based on sinusoidal phase-modulating method is developed for vivo imaging of human skin. A complex spectral interferogram is retrieved based on Fourier transform analysis and bandpass filter of phase-modulated interference spectra, which is recorded with sinusoidal phase modulation introduced during lateral beam scanning. With the system, the depth imaging range is doubled and the signal-to-noise ratio degrading with the lateral scanning is avoided. Also the system is suitable for vivo imaging. 3D vivo full-range OCT images of human skin is achieved with the proposed system. In the images, the stratum corneum, the epidermis and the upper dermis can be clearly identified. By optimizing the sampling number in one modulation period, the complex conjugate rejection ratio is improved, which is about 36 dB.

Raman spectrum and surface enhanced Raman scattering (SERS) spectrum of the nude mouse serum are measured using laser Raman confocal micro-spectrometry. The results show that the Au nanoparticles active substrate can enhance the Raman spectra dramatically. A lot of information which conventional Raman spectroscopy fails to detect emerges. This is due to the chemical adsorption and interactions between the gold nanoparticles and the substances in serum. The information is important for the analysis of the most components and structures of the serum proteins. With SERS spectrum, even micro-sample can also reflect the molecular structure information of the serum proteins, lipids, carbohydrates, ribonucleic acid and other components. Information of the serum components can reflect physiological and pathological metabolism changes of the cells and tissues in the body. So SERS spectrum of the serum would provide an effective means for the diagnosis and therapy of diseases.

Raman microspectroscopy can provide molecular-level finger-print information about the biochemical composition and structure of cells and tissues with excellent spatial resolution. Raman spectroscopy of nasopharyngeal carcinoma cell lines C666-1, CNE2 and normal nasopharyngeal cell line NP69 are presented to investigate the differences between them. The ratio of I1449/I1657(1.10) seems to very easily divide tumor and normal cell lines into two groups, and this result is coincident with the existing report about the study of normal and malignant bronchial tissue. Principal component analysis (PCA) and linear discriminant analysis (LDA) are also used to classify different cell lines and achieve an exciting result with a sensitivity and specificity of 90% and 100%, respectively. The results of the work may be helpful to the discrimination of normal and tumor cells, which show that Raman spectroscopy can be one of the diagnostic methods of nasopharyngeal carcinoma and do favor to the early diagnosis.

Flow velocity measurement based on speckle in optical coherence tomography (OCT) images is developed. Similar to traditional laser speckle signal, time-varying fluctuations in OCT speckle intensity is related to the average velocity of scattering particles within the sampling volume. Fluctuated signal of the speckle intensity is obtained from the detected OCT signal by filtering and demodulation. Then the spectrum of the speckle is deduced through Fourier transform of the fluctuated signal, and quantitative measurement of flow velocity can be conducted according to the calculated ratio of high to low (HLR) spectrum. The method of flow measurement based on speckle intensity in OCT instead of phase information is introduced. Investigation on the relationship of the calculated HLRs with the flow velocities is experimentally conducted. Flowing particles in a tube in mimic of capillary is visualized by the proposed method.

Identification and analysis of five different types of white blood cells (WBCs) have a very important application in many fields, such as clinical medicine and life science. In recent years, the digital phase microscopy techniques of red blood cells are remarkably expanded in their observing application. However, due to special optical phase structures of WBCs, the techniques of phase microscopy have difficulty in studying them. Based on this, the analysis of optical characteristics of five types of WBCs is done, and optical models of them are built in this paper. Distribution characteristics of WBCs under these phase models are obtained with numerical simulation techniques. It is found that phase distribution of WBCs is not only related to interference, but also to the scattering of nucleus by analyzing the relationship between phase distributions and classifications of them, but it has certainty to some extent.

To investigate blood vessel remodeling in the process of He-Ne laser irradition on periodontium of experimental tooth movement, a He-Ne laser with weavelength of 632.8 nm and power of 20 mW is used to irradiate the periodontium of experimental tooth movement in rats. Periodontal slice is treated by cyclooxygenase-2 (COX-2) immunohistochemistry dyeing and the results are obtained by image analysis. The results show that the COX-2 expression in periodontium with forced time of 3, 5, 7 d are significantly higher in experimental side than that of control side in the pressure region. While in the tension region, the COX-2 expression in periodontium with forced time of 1, 3, 5, 7 d are significantly higher in experimental side than that of control side. The results indicate that He-Ne laser can increase COX-2 expression in periodontium during the tooth movement in rats, thus probably enhance the vascularization of tooth movement.

In fluorescence microscope, the weak fluorescence signals are usually submerged in the strong excitation light. The fluorescence microscope image quality seriously depends on the ability to extract the faint fluorescence signal from the strong excitation light. At present, the image enhancement using frequency filtering to filter out the excitation light, is often used in the fluorescence microscope, based on the differences between fluorescence and excitation wavelength. However, while this method is used, the parameters of the filter will be required highly, and seriously depend on the wavelength of the fluorescence and the excitation light. A polarization filtering image enhancement technology to filter out the excitation light and enhance image quality, is proposed, based on the differences of the polarization characteristic between the fluorescence and the excitation light. The experimental results indicate that when the filtering method is utilized, the image quality is improved significantly, and the requirements of the optical components performance parameters, is significantly reduced. The study is not only to enrich the technological method to extract the weak fluorescence signal from the strong excitation light, but also a reference for developing a light wavelength tunable multi-spectral fluorescence microscope.

The number density of photons absorbed in semi-infinite plane, simple columnar and double columnar biological tissues is numerically studied with Monte-Carlo method, respectively. The same optical parameters are used in the simulation for the three situations. The results show that the boundary employed in the simulation has important effect on the light propagation in tissue. The effect of boundary on light propagation in tissue is investigated. Energy flow rate in biological tissue as a function of radial distance is simulated and the results agree well with experimental results.

As a new and developing medical imaging technique, the digital tomosynthesis imaging (DTS) can provide researchers with confidence to distinguish the overlapping lesion tissue and make exact lesion-localizing. DTS employs the filtered backprojection algorithm for its rapid reconstruction speed and high reconstruction quality and reconstructs a series of the coronal images. However, the digital tomosynthesis insufficient dataset causes the hat-like intensity drop in its filtered backprojection reconstructed images along the rotation axis. The cone angle impact on the digital tomosynthesis axial intensity drop is analyzed and a reciprocal-cosine weighted intensity correction is introduced. To validate the effect of the axial intensity drop correction method, a DTS system is designed and built up and the anthropomorphic breast phantom is reconstructed with the reciprocal-cosine weighted correction method under different cone angle respectively. The reconstruction results demonstrate that the correction method can effectively minimize the axial intensity drop in digital tomosynthesis reconstructed images.

Signal attenuation is highly concerned in many research fields. Imaging quality and depth in photoacoustic (PA) imaging system are often limited by the attenuation of PA signal. The PA signal attenuation is induced by many factors in PA imaging system. The factors leading to the signal attenuation and its characteristics are discussed based on tissue optics, acoustic transport and detection in a long-focal-zone PA imaging system. Considering to recover the PA signal from optical to ultrasonic attenuation, a method to compensate the detected PA signals is presented. The proposed method is evaluated by simulant sample and employed to image a thyroid tissue in vitro. The experimental results demonstrate that the method could be used to recover the PA signal and to improve the imaging depth and quality in the PA system.

Functional near infrared spectroscopy (fNIRS) technology is utilized to monitor brain tissue of rat model of traumatic brain injury (TBI). The reduced scattering coefficient of the local cortex of rats is monitored and recorded in vivo and real time by the fNIRS system. Brain water content (BWC) is measured by the wet and dry weight method. Intracranial pressure (ICP) is measured invasive ICP monitor. Imaging data of rat model is detected by small animal magnetic resonance imaging (MRI). Experimental results show that, there exists positive correlation between parameters and BWC, and ICP, the occurrence and development of cerebral edema can be detected earlier with the sensitive indicator of scattering coefficient.

Base on two cancerous samples various polarization parameter images are obtained by using three kinds of polarization imaging methods. It is analyzed that different polarization parameters′ character capabilities in different cancerous tissues and normal tissues. The results show that the polarization method can be applied to the detection of cancer. According to the physiological and optical properties of cell, the Monte-Carlo simulation using simple scattering model is carried which agrees the experiment results and shows the potential of polarization imaging in the detection of cancer.

Light is one of the precipitating factors of red tide, and the intensity of light plays a key role on the growth of red tide advantage algae. Monochromatic LEDs are used as the light source to cultivate dinoflagellate Prorocentrum lima and diatom Skeletonema costatum. When temperature and light cycle are fixed, to investigate the effect of different light intensities of green, red and blue light on the growth rates and spectrum absorption coefficient of algae is investigated. The results show that the saturated light intensity of blue light of Prorocentrum lima and Skeletonema costatum are the lowest, and the saturated light intensities of red light of Prorocentrum lima, and green light of Skeletonema costatum are the highest, respectively. Within saturated light intensity and the same light intensity, the growth rates of Prorocentrun lima and Speletonema constatum are the largest in blue light, but lowest in red and green light, separately. Besides, it is concluded that the growth rates of two algae are positive to the spectrum absorption coefficient, while saturated light intensity is negative to the spectrum absorption coefficient under different monochromatic lights.

To explore the feasibility of surface-enhanced Raman scattering (SERS) labeled immunoassay technology for clinical analysis protein expression in colon cancer tissue sections, we develop 4-mercaptobenzoic acid (4-MBA) labeled Au/Ag core-shell nanoparticles (NPs) as assay platform for the detection of carcinoembryonic antigen (CEA) in colon cancer tissue samples. Firstly, Raman active molecule 4-MBA is adsorbed on Ag shell Au core bimetallic NPs, and then the SERS-tagged nanoprobes are modified with CEA monoclonal antibody, forming CEA-SERS probes. Finally, according to the theory of specific binding of SERS-tagged antibody and the corresponding antigen, SERS spectra and imaging are performed in tissue sections after dropping the SERS-tagged immuno-nanoprobes. Data show that colon cancer epithelium appears strong SERS signals, while stroma and normal epithelium do not appear SERS signals, except a few non-specific adsorption signals. As can be clearly seen from the SERS images, the colon cancer epithelium highly expresses CEA, while stroma and normal epithelium do not. In conclusion, due to high sensitivity and high specificity of SERS-tagged immuno-nanoprobes, the SERS labeled immunoassay technology is promising for the analysis of the protein expression in colon cancer tissue sections and has the potential to be developed into a significant aiding tool for pathological diagnosis of colon cancer.

The effects of low intensity 810 nm laser irradiation (LIDL) to the tumor necrosis factor (TNF)-α induced expression suppression of circadian clock genes in cultured NIH3T3 fibroblasts are investigated. The fibroblasts shocked by horse serum for 2 h are induced with TNF-α of 10 ng/mL, and then irradiated by different doses of LIDL once. The results show that TNF-α induced inhibition effect of the circadian clock gene expression can be modulated by LIDL, which may be mediated by nicotinamide adenine dinucleotide/ reduced form of nicotinamide adenine dinucleotid (NAD+/NADH) and sirtuin 1 (SIRT1).

The seedlings of wheat (Jinmai No.8) are exposed to He-Ne laser irradiation (5 mW/mm2) and enhanced UV-B radiation [10.08 kJ/(m2·d)], the polyacrylamide gel electrophoresis (PAGE) is used to analyze the patterns of peroxidase (POD), catalase (CAT), esterase (EST), adenosine triphosphatase (ATPase), and malate dehydrogenase (MDH). The results have shown that two new bands of POD zymogram appeare under enhanced UV-B radiation, but the activities of the total POD isoenzymes decrease. However, there is no difference among isoenzyme bands of CAT, EST, ATPase, and MDH, but the activity of the isoenzymes decreases obviously. Our study find that the gene expression and activities of plant are weakened by UV-B radiation, but the ability of plant stress resistance is enhanced by He-Ne laser irradiation.

In dioptric media, due to the refraction of probe light in the sample and the mismatch of the optical distance with the actual distance, a major impediment to the use of optical coherence tomography (OCT) is its image distortions. This paper describes ray trace method of geometrical optics algorithm for numerical correction of the unavoidable image distortions in the raw image obtained by fiber based spectral domain OCT system, and theoretically deduces the mapping from the raw image of dioptric media to its actual structure. Experimentally, this method is adopted to correct the image of the glass tube and the anterior segment of human eye. The reconstructed image of the glass tube is coincident with the actual structure, and the measured physiological parameters of the human eye, such as cornea thickness, anterior chamber depth and width, pupil width, curvature radius of front and rear surface of cornea, and curvature radius of front surface of lens, are within the reference ranges given by the model one. The method enables OCT system to be applied to dioptric media containing multiple refraction interfaces, including the imaging of complicated optical system consisting of battery of lenses.

In order to explore optical transmission characteristics between meridian tissue and non-meridian tissue before and after moxibustion, a self-made device is used to detect optical transmission characteristics with high sensitivity. The optical transport characteristic of pericardium meridian before and after moxibustion neiguan acupoint is reserched, optical transport characteristic of the non-meridian tissue before and after couterizing non-acupoint point is also researched which is 1 cm far away from neiguan acupoint. The optical transmission efficiency in pericardium meridian and non-meridian tissue both decrease after moxibustion, but there is a much more significant decrease in pericardium meridian than non-meridian tissue(P<0.05). These findings suggest that the optical transmission characteristics of pericardium meridian and non-meridian tissue are different, and pericardium meridian appears more sensitive to moxibustion. The results herein can offer beneficial reference in meridian studies and clinical application of moxibustion.

Vortex optical trap is generated by projecting computer-generated phase patterns to liquid crystal spatial light modulator. Because vortex beam itself owns orbital angular momentum, it can be utilized to trap and rotate yeast cell. The angular rotation rate of yeast cell is measured by Fourier transforming of rotation time-sequencial signal. Besides, how laser power, topological charge and height of the vortex trap from bottom affect the angular rate of rotation is discussed in detail. The experimental results indicate that the rotation rate is proportional to laser power, but inversely proportional to the square of the topological charge. The rotation rate reaches maximum when the height of trap is about 14 μm. The sign of topological charge determines the direction of rotation of yeast cell. When the sign of topological charge is positive, the yeast cell rotates counter-clockwise, and it rotates clockwise when the sign is negative. The results may find their potential applications in the measurement of the torque of bacterial flagella motor.

Skin welding with a combination of 1064 nm and 980 nm diode lasers, which′s the first-time discuss in the literature, was performed in this study. The long-time effect of laser skin welding was investigated through macroscopic and microscopic examinations as well as tensile strength tests at different time after the welding, comparing with that of conventional suturing. At the same time, the temperature of rat skin tissue during laser-welding was measured in vivo with a thermo-couple temperature measurement in order to analysis the relation between the effect of tissue welding and tissue temperature. Using a power density of 15.92 W/cm2 with power of 0.5 W in continuous wave mode and exposure time of 5 seconds per spot for both 980 nm and 1064 nm lasers, it′s found that laser tissue welding yielded more effective closure and healing than conventional suturing technique that with faster recovery, better apposition of tissue, less tissue interaction and tighter closure. As a result, tissue welding with a combination of two near-infrared lasers is an effective method for wound closure, and further investigations are in progress for clinical use.

Bonding interface changes on different types of dentin after Er:YAG laser irradiation is evaluated. Normal dentin (ND) group and caries affected dentin (CAD) group samples are respectively irradiated with Er:YAG laser, and then etching with 38% phosphoric acid(phosphoric acid group), low-dose Er:YAG laser radiation (laser group) and no treatment (control group). The bonding interface changes are assessed via confocal laser scanning microscope (CLSM). There is no significant difference in thickness (p>0.05) within the same group with different etching methods or among different groups with the same etching, however, significant differences are existed in the length of resin tags (p<0.05). Maximum resin-tags are achieved in the phosphoric acid group, while control group minimum. Resin-tags in the bonding interface of ND are longer than that of CAD. The adhesive can infiltrate well into dentin bonding interface to achieve a quite ideal resin tags in the ND groups etching with 38% phosphoric acid.

It is known that artesunate (ART) induced apoptosis is due to the reactive oxygen species (ROS) generation which triggers many apoptosis. DCFH-DA and Rhodamine 123 were used to probe the level of ROS and mitochondrial membrane potential. Time-lapse confocal fluorescence microscopy was used to monitor the dynamics of ROS generation and the loss of mitochondrial membrane potential during ART-induced human lung adenocarcinoma cells (ASTC-a-1) apoptosis. The data show that the cell ability can be reduced by ART of 0~50 μg/mL. ART of 40 μg/mL which be used to generate significantly ROS can induce notablely loss of mitochondrial membrane potential. Results show that N-acetylcysteine (NAC), a scavenger of ROS, can significantly inhibits the ART-induced apoptosis and the loss of mitochondrial membrane potential and ART induces ROS-mediated apoptosis and loss of mitochondrial membrane potential.

A fast photoacoustic imaging system based on multi-channel parallel acquisition, which is composed of ultrasonic detector, multi-channel parallel acquisition system, short-pulse laser, computer hardware platform and a pack of software for the control of the data acquisition and real-time imaging, is designed. Multi-channel parallel acquisition system consists of front-end analog amplifier, anti-aliasing filter, A/D converter, data storage, field programmable gate array (FPGA) control and universal serial bus (USB) transfer and it has 64-channel full parallel acquisition and digital processing. The results of imitative sample show that multiple locations of rotating scan imaging improve the signal to noise ratio (SNR) greatly. Consequently, it is characterized by fast imaging and is expected to be a noninvasive real-time tissue imaging system with high repetition frequency laser as excitation and provide a new method for clinical noninvasive detection.

A broad-band high-speed linearized swept laser source based on grating/polygon mirror tunable filter is reported. In order to facilitate the filtering system, the tunable filter consists of polygon scanner and grating in Littrow telescope-less configuration. Parallel implementation of two semiconductor optical amplifiers with different wavelength ranges is adopted in the laser resonator for broad-band light amplification. Center wavelength of the developed swept laser source is 1312 nm with a turning range of 170 nm and 3dB bandwidth of 116 nm. A repetition frequency up to 50 kHz with an average output power of 2 mW is realized while the polygon is scanned at a speed of 695 r/s. This high-speed broad-band linearized swept laser source is especially applicable to high resolution swept source based optical coherence tomography, of which the axial resolution can reach to 6.5 μm.

Two type degeneration processes: dehydration and proteolysis are studied, and the description based on polarization sensitive optical coherence tomograph (PS-OCT) measurement is presented respectively. Birefringent changes due to dehydration or proteolysis process are different. For the former case, the average birefringence increases with dehydration, caused by the size and index changes of muscle fibers. However, the hydrolysis process shows an opposite tendency. The average birefringence decreases with proteolysis, which can be explained by the damage of fibrous microstructures and the appearance of isotropic scattering elements. The above experimental results reveal different optical and microstructural changes in these two degeneration processes, and can be used to evaluate the muscle quality.

This paper describes the application of an improved synthetic aperture technique based on phase compensation. This technique corrects the phase distortion of the echoes caused by ultrasound degradation to enhance the resolution of endoscopic ultrasonography. The degradation of the echoes in lateral and axial directions is investigated to obtain the impact of center frequency and lateral resolution caused by ultrasound degradation. Two different cross correlations are implemented to compensate the phase distortion in both lateral and axial directions. One is achieved in the form of segmented cross correlation in axial direction to evaluate the instantaneous change of phase. The other one is used to compensate the remnant phase distortion after range curve correction to enhance the performance of lateral pulse compression. The results of simulation indicate that phase compensation can improve the resolution and signal-to-noise ratio (SNR) of ultrasound images. The increases are 0.2 mm and 1.6 dB in resolution and SNR, respectively, compared with the uncompensated images. It can be concluded that phase compensation has the potential to enhance the resolution and SNR.

The histological changes of bone defect sites created surgically in rat femur treated by low level laser therapy (LLLT) are evaluated. Thirty rats are randomly divided into 3 groups according to different methods of laser irradiation: multi-irradiated group, single-irradiated group and control group with no irradiation. The total doses of both of the irradiation groups are the same. A round bone defect is created on the femur of each rat. The rats are killed on the 15th day and the 30th day after the surgery. The results show that after drawing materials and HE staining, the inflammation and bone formation of each group are analyzed under an optical microscope. The inflammation scores of irradiated groups are lower than those of control group with significant difference, meanwhile, the bone formation scores of irradiated groups are higher than those of control group with significant difference. However, there is no significant difference between the two irradiation groups. It is concluded from the study that LLLT with proper dose may alleviate inflammation and promote bone formation. There is no difference between multi-irradiated group and single-irradiated group.

Multislice computed tomography (MSCT) is noninvasive and 3D imaging compared with the traditional coronary angiography (CAG). An optimal CAG viewing angle algorithm based on MSCT vessel analysis is proposed. First, a local vessel enhancement based on optimal oriented flux and locally adaptive threshold region growing is applied to extract the 3D coronary arteries model and then 3D thinning is performed and segment of interest is selected. According to the parameters during CT and CAG data acquisition, a perspective projection is performed to simulate the CAG procedure and the optimal viewing angle is calculated with the minimum foreshortening and minimum overlapping principle. Experimental results illustrate that the foreshortening percent is less than 1% in the obtained angle,which is close but superior to the working view angle. Therefore it can be applied to coronary artery disease intervention planning.

The forming process of the photoacoustic signal excited by the intensity-modulated continuous-wave laser and the effects of modulation pulse width on photoacoustic signal are researched. It is shown that the power absorbed by the biological tissue increases with the increase of the width of the modulated rectangular pulse and the amplitude of the photoacoustic signal. The effects on the axial resolution of the photoacoustic signal excited by the modulated rectangular pulse are also researched. It is shown that the width of the photoacoustic signal increases with the increase of the width of the modulated rectangular pulse, and the axial resolution of the photoacoustic imaging becomes worse. The modulated rectangular pulse of the continuous-wave laser (laser diode) is used to induce the acoustic signal. The laser power density is raised to obtain photoacoustic imaging with higher signal-to-noise ratio (SNR) and resolution when it is hard to raise the laser power. The research on the influential factor of photoacoustic signal excited by intensity-modulated continuous-wave laser in biological tissue can be used to provide a portable and lower cost instrument.

According to the morphological structures of leukocyte, the double layer eccentric-sphere model is established for a kind of single-nuclear cell. Based on the Mie scattering theory and interface transfer theory, the expressions of amplitude functions are revised by the geometrical-optics approximation. Results of numerical calculation are consistent with the results from the VirtualLab imitation system which calculate by finite element method. Results of numerical calculation also show that three kinds of intensity modulations with different frequencies can be found in the angular distribution. The physical mechanism about these three modulations has been analyzed. The relations between the modulation characteristics and the physical and optical parameters of the cell are obtained. The modulation distortion phenomenon will appear in the case of nuclei close to the cell. These provide a useful theory foundation for improving the measuring and identification technique of single cells.

To investigate the feasibility of in vivo effect assessment monitoring by functional near infrared spectroscopy (FNIRS) during laser induced interstitial thermotherapy (LITT) in real time, the reduced scattering coefficient during LITT therapy by different laser powers and heating time on Fresh pork liver in vitro and the subcutaneous implanted rat liver cancers by FNIRS system are recorded in vivo. The reduced scattering coefficient (s）which gets through the FNIRS increases during LITT, it increases quickly at beginning, and gradually reaches the stable state. s rises faster when the laser power is greater. There is the same changing trends of s of different tissues, but there is difference between the curve shapes. The system of FNIRS can be used to assess the therapy effect during laser induced interstitial thermotherapy in vivo, and s can be used as a new effect assessment factor. By monitoring the changes of s can effectively guide clinical therapy.

The influence of an applied water film on bone hard tissue ablation by pulsed CO2 laser is evaluated. Fresh bovine shank bone in vitro used in the experiment is put on a PC-controlled motorized linear drive stage and is moved repeatedly with the speed of 12 mm/s through focused beam of laser. In each sample, two cuts are produced, one with water film and the other with not. The wavelength of pulsed CO2 laser is 10.64 μm, the pulse repetition rate is 60 Hz, the energy density is 18～84 J/cm2, the beam diameter is about 400 μm and the water film tickness is 0.4 mm. The scanning number is five. The surface morphology and microstructure of ablation grooves are examined by steroscopic microscope and scanning electron microscope (SEM) respectively. The crater depth is measured with optical coherence tomography (OCT). It shows that water film can not only reduce carbonization and thermal damage, clean the ablation groove, but also augment ablation rate at the radiant exposure of 50 and 70 J/cm2.

Linear regression theory is introduced to analyze the process of photoacoustic image and the algorithm of multi-wavelength component concentration distribution is constructed. Computer simulation and biological tissue sample experiment are carried out to prove that the algorithm can make photoacoustic image reflect more biological tissue information. During the experiment, all parameters are kept as constant except the wavelength of exciting pulsed laser. The result shows that the information reflected by photoacoustic image of single wavelength matches well with the absorption of mixture component at excited wavelength. Photoacoustic image of single length cannot fully indicate the distributions of each component when the component absorptions are quite different. Based on this, the distribution information of image components changes and matches well with real sample after being treated by the algorithm.

The objective of this study is to test whether hydrogen peroxide (H2O2) is involved in laser pretreatment induced drought tolerance in wheat seedlings due to its nature as a second messenger in stress responses. Plant is treated with 3 min CO2 laser pretreatment, laser pretreatment in combination with catalase (CAT), ascorbate (AsA) or diphenylene iodonium (DPI) and their effects on the lipid peroxidation, the activities of antioxidant enzymes and the concentration of photosynthesis pigment and seedlings growth and development were compared. The results show that 3 min laser pretreatment can enhance drought tolerance in wheat seedlings by decreasing the concentration of malondialdehyde (MDA) and increasing the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and the concentration of chlorophyll a, chlorophyll b, carotenoid and plant height, root length and root dry weight. But the promotive effect of laser pretreatment induced drought tolerance in wheat seedling is effectively reversed by the addition of CAT, AsA or DPI. The results suggest that H2O2 is involved in laser pretreatment induced drought tolerance in wheat seedlings and laser induced protective effect is likely related to NADPH oxidase-dependent H2O2 production.

The analytic solution for spatially-resolved diffuse reflectance based on the Delta-P1 approximation for the two-point-source approximation is investigated. We have derived the radiative transport equation and the expression of the effective source by using scattering phase function which contains Dirac delta function. The analytic solution RDelta-P1,2(ρ) considering two-point-source approximation to the Delta-P1 model is presented. By comparing RDelta-P1,2(ρ) with the diffusion approximation RSDA(ρ),it is demonstrated that the Delta-P1 approximation RDelta-P1,2(ρ) models the radiance in moderate albedo media or close to source (ρ about 1.5 mm) more accurately than diffusion theory with the relative errors within 15%. Furthermore,the analytic solution RDelta-P1,2(ρ) provides the prediction of the second-order parameter γ of phase function,which is important for developing the inversion algorithm to recover optical parameters from the spatially-resolved diffuse reflectance measurements with small source-detector separations.

Fe-based WC composite coatings are prepared on the surface of A3 steel by laser induction hybrid rapid cladding (LIHRC). Microstructure and microhardness characteristics of the composite coatings are investigated. The results show that WC particles are almost dissolved completely and interact with Fe-based alloy,so that M6C are precipitated in the Fe-based interdendrite matrix phase. The reason why the microhardness of Fe-based WC composite coating is relatively low is that WC particles are dissolved completely and the retained austenite is precipitated during laser induction hybrid rapid cladding.

To compare the related physiological and biochemical parameters of “Sanjiao fragrant glutinous rice from Yao’an county” and its induced variety treated by laser and electric field. To measure the content of chlorophyll a,chlorophyll b,Lys,Pro under low temperature treatment and soluble sugar;the activity of amylase,catalase and nitrate reductase;seed vigor and respiratory rate. The activity of catalase and nitrate reductase,respiratory rate,and the content of Lys did not change so much;the activity of amylase declined;but the content of chlorophyll a,chlorophyll b,soluble sugar and seed vigor increased by laser and electric field treatment. The related physiological and biochemical parameters of “Sanjiao fragrant glutinous rice from Yao’an county” and its induced variety treated by laser and electric field have changed,some of them increased,whereas some of them decreased.

The purpose of this study is to investigate a relationship between the structure of lipid and colorectal carcinogenesis at the molecular level. Colorectal cancer specimens and adjacent normal tissues were measured using confocal Raman microscopy system. The bands at 2857 cm-1 and 2891 cm-1 originate from CH2 symmetric and asymmetric stretching vibrations,respectively. The band at 2938 cm-1 arises from symmetric C-H stretching vibrations. The results show that there are prominent differences between colorectal cancer specimens and adjacent normal tissues in Raman spectroscopy:1) The intensity of the bands of the cancer tissue spectrum at 2857 cm-1 and 2891 cm-1 are reduced compared with those of the normal spectra. The relative intensity of the band at 2938 cm-1 of lipid of colorectal cancer is stronger than that in normal tissues. 2) The average ratio (I2891 / I2857) values is reduced compared with those of the normal spectra. The values for normal and cancerous tissues are 2.21 and 1.69 by the function of ‘compare means’ of SPSS16.0 software. The research results demostrated that the lateral packing of lipids is loosened which may result in the fluidity of lipid to be increased and the interactions of lipid and protein increase when normal cells are transformed into cancerous cells. Our data suggested there is the relationship between the stretch vibrations of lipids and colorectal carcinogenesis.

To observe the influences of different daily doses between 1-4 J/cm2 of low-level laser therapy (LLLT) on wound healings,the dorsal cutaneous excisional wounds of Wistar rats were irradiated with 630 nm at three daily doses of 1.2 J/cm2,2.4 J/cm2 and 3.6 J/cm2 under a constant power density of 10 mW/cm2. The analysis of variance (ANOVA) of areas of the wounds indicates that there were no statistical differences among the control group and the other three different doses groups. However,microscopic observations,both hematoxylin and eosin staining and Masson staining,could tell evidently better results of LLLT groups when compared to the control group,including the shorter period of inflammation,the greater development of granulations and collagens,and better epithelialization. The microscopic evaluations also suggest that larger dose brings better wound healing results within the 1-4 J/cm2 range.

An image reconstruction method for time-domain fluorescence diffuse optical tomography is proposed using a two-dimensional (2D) turbid medium of circular domain. The methodology based on a linear generalized pulse spectrum technique, employs analytic expressions of the Laplace-transformed time-domain photon-diffusion model to construct a Born normalized inverse model. The resultant linear inversions introducing a pair of real domain transform-factors are solved with an algebraic reconstruction technique to separate distributions of the fluorescent yield and lifetime. The effectiveness and feasibility of the proposed scheme have been validated by experiment using multi-channel time-correlated single-photon-counting system. The results show that the approach retrieves the position and shape of the targets with a reasonable accuracy.

Two near infrared fluorescence probes (i.e., folate-PEG-ICG-Der-01 and LDL-ICG-Der-02) are synthesized. Here, over-expressed folate receptors and low density lipoprotein (LDL) receptors in some specific tumors are chosen as target. The residues of folic acid and LDL, as the targeted ligand, are covalently conjugated to organic near-infrared fluorescence dye ICG-Der-0 and ICG-Der-02 respectively, where near-infrared dyes are the output of fluorescence signal. The optical properties of the two probes are characterized by ultraviolet spectrophotometer and near-infrared fluorescence spectroscopy system. The imaging process of folate-PEG-ICG-Der-01 and LDL-ICG-Der-02 probes in tumors which over expressed folate receptors and LDL receptors is further detected by near-infrared fluorescence imaging system. The results show that as-prepared folate-PEG-ICG-Der-01 and LDL-ICG-Der-02 probes present higher fluorescence intensity and better photo stability than those corresponding near-infrared fluorescence dyes. And the results of in vivo near-infrared fluorescence imaging confirme that these two probes are highly bioactive, can efficiently target tumor sites, and finally be eliminated. Compared with LDL-ICG-Der-02, the targeting capability of folate-PEG-ICG-Der-01 probe is more effective, and has great potential in non-invasive real time early tumor diagnosis.

The Kunming mice immatured oocytes in vitro maturation culture system are established to investigate the reproductive toxicity of CdSe/CdS/ZnS quantum dots (QDs). QDs stock solution is added into oocyte culture medium at a final concentration of 28.90 nmol/L. Then, QDs and oocytes are co-cultured at 37 ℃, 5% CO2 for 4, 8 and 20 h, respectively. The morphological information of oocytes are observed and analyzed under phase-contrast fluorescence microscope. The results demonstrate that QDs enter cumulus cells and accumulate with co-culture time. QDs can not penetrate oocytes zona pellucida, which is confirmed by laser scanning confocal microscope with high spatial resolution. After being treated for 20 h and being rejected by oocytes, QDs decrease the ratio of oocyte in vitro maturation dramatically.

In the spectral optical coherence tomography(OCT) system, a high depth of field can be achieved at the expense of the poorer transverse resolution. Interferometric synthetic aperture microscopy (ISAM) is an optical computed-imaging technique, which can make transverse resolutions at the different depths identical by resampling the spectrum data. The procedure of ISAM and the principle of error were analyzed and a reconstruction model of multi-scatterers is established. The multiple scatterers simulation is implemented by use of ISAM compared with the standard OCT methods. The approximate wavenumber domain algorithm is applied in ISAM, which can save much rebuilding time without the Stolt interpolation and the spectral OCT experiment system was developed. The experimental results showed that it can greatly reduce computational complexity to enhance the performance of real-time, which costs 50 s to finish one 320 pixel×265 pixel image.

The photothermal therapy which mainly uses near-infrared laser to heat tissue has become a new validated method for tumor treatment through direct surface irradiating or inserting light fibers in tumor. The near-infrared light transfer in tissue is limit and the thermal effect occurs only in a small volume during treatment. Thus the treating extent is difficult to control. Otherwise, it is difficult to distinguish the boundary of tumor and normal tissue in photothermal therapy. Improper heating will hurt the normal tissue. So it is important to guide the laser in time in thermal therapy. The results indicate that by using upconversion nanoparticles[Yb/Er (NaYF4Yb, Er)] to localize on tumor, the infrared light can be monitored in real time with the upconversion fluorescence. The light dosage, distribution, heating extent and the boundary of tumor can be detected to increase the effect of thermal therapy.

Super resolution imaging technique has become a key tool in imaging the structure and function of living cells. Localization of single fluorescent molecule is an integral part of super resolution imaging. From the point of view of super resolution imaging, a rigorous comparison of the performance of the different algorithms under experimental conditions is necessary. In this paper, five commonly used localization algorithms: centroid method, generalized centroid method, Gaussian fitting, fluoroBancroft method, and maximum likelihood method are investigated, and how well these algorithms work is clarified. The results show: firstly, Gaussian fitting, generalized centroid method and maximum likelihood method are high localization precision method and have been slightly influenced by extracting sub-window. Secondly, centroid method and fluoroBancroft method could be applied in on-time imaging, however, they have low localization precision and are influenced by extracting sub-window. Thirdly, for the five algorithms, the localization precision is abruptly decreased when there are two molecules in a diffraction spot.

Early dental caries is caused by demineralization of the teeth, which results in the increasing backscattered coefficient of the lesion area. In the paper, a method is proposed for detecting early caries by using optical coherence tomography (OCT). The two dimensional tomography images of the human teeth in vitro are obtained by using the development all fiber OCT system. Artificial caries model is made by chemical etching on the human teeth in vitro for 12, 24, 48, 72, 96 and 120 h, respectively. Using the OCT system, the level of demineralization is obtained quantitatively and the measurement data are obtained with different artificial time. The result shows that the depth of the artificial caries has the linear relationship with time. It is proved that OCT has the feasibility by detecting the level of demineralization for early caries diagnosis.

Optical coherence tomography (OCT) is used to investigate the microstructure changes of human fingernail induced by hydration. Images of nail plate are obtained to display the morphology of fingernail and to disclose the keratinization of basal cells of nail plate. Combined with digital vernier caliper, this imaging technology is used to evaluate thicknesses and changes of nail in vitro after immersion with time. OCT images of nails show that the dorsal and ventral layers of nails have similar thicknesses which are much thinner than intermediate layer. The total thickness of fingernail exponentially increases with immersion time, and the saturating phenomenon appears at about 12 min. Three layers show different contributions to the total increase of the thickness of 17.4%. Microstructure changes in vivo are similar to the results in vitro. The changes of optical path length also could be evaluated by this method. OCT is capable of reflecting precise microstructure changes, and it has the potential to provide physician with a modern and objective diagnostic standard for nail inspection (NI) and to monitor disorders in Chinese traditional medicine (CTM) clinical practice and research.

Treatment of metastatic cancer remains a great challenge and needs novel approaches. Combining a selective photothermal therapy with an active immunological stimulation, laser immunotherapy (LIT) was developed to induce systemic immune responses through local intervention. LIT consists of three major components: a near-infrared laser, a light-absorbing agent, and an immunological stimulant. Its effect relies on two major interactions: a selective photothermal interaction and an active immunological stimulation. The selective photothermal interaction can reduce the tumor burden and at the same time release the tumor antigens, which can induce specific antitumor immune response. The expression of heat shock protein and the application of immunoadjuvant further enhance the host immunity. It has been proved in pre-clinical studies that LIT could not only eradicate treated local tumors but also regress and eliminate untreated metastases at distant sites. Moreover, LIT is well tolerated and has shown to have many advantages for cancer treatment compared with other traditional modalities.

Synthetic aperture focusing, widely used in radar system, is introduced into endoscopic ultrasound imaging system in this paper. Based on the features of synthetic aperture focusing (SAF), a method of synthetic aperture imaging for ultrasonic endoscope is presented, using the rotation effect of a probe with single transducer, transmitting and receiving the echoes at different time and different locations during the rotation, synthesizing a large transmitting aperture equivalently to enhance the signal to noise ratio and the resolution of the ultrasonic images. The principle of synthetic aperture technique was analyzed, which is used for endoscopic ultrasound imaging with single transducer probe, and then the longitudinal and lateral compression were implemented according to the coded and linear frequency modulated characteristics of the echoes. Finally, an experiment was completed, using a transducer, with the center frequency of 8 MHz, to detect a pigskin sample, the target with the size of 0.8 mm×2 mm could be identified, and the signal to noise ratio had an improvement of 9.38 dB.

In order to simplify the thighbone tumor surgery and improve the accuracy of the areas to be cut, a kind of surgery orienting model for the surgery operation is designed according to the scanning data of computer tomography (CT) and the three-dimensional reconstruction image. By using the Dimetal-280 selective laser melting rapid prototyping system, the surgery orienting model of 316 L stainless steel is made through orthogonal experiment for processing parameter optimization. The technology of direct manufacturing of surgery orienting model by selective laser melting(SLM) shows obvious superiority with high speed, precise profile and good accuracy in size comparing with the traditional ones. The model has been well applied in a real surgery operation for thighbone replacement operation. The successful development of the model provides a new method for the automatic manufacture of customized implants and surgery model, and will build a foundation for more clinical applications in the future.

In order to determine the repair role of laser in the damage induced by ultraviolet-B (UV-B) radiation, the effects of He-Ne laser (5 mW·mm-2) irradiation on Ca2+-ATPase， Mg2+-ATPase and Na+/K+-ATPase activity in six days seedlings of wheat after enhanced UV-B (10.08 kJ·mm-2·d-1) radiated were studied. The results showed that the Ca2+-ATPase activity and Mg2+-ATPase activity under UV-B handling were lower than CK group(P+/K+-ATPase in contrast (P＞0.05); the Ca2+-ATPase activity, Mg2+-ATPase and Na+/K+-ATPase activity under the He-Ne laser radiation were higher than the CK group(P2+-ATPase, Mg2+-ATPase activity were higher than the one under UV-B handling, but lower than CK group, Na+/K+-ATPase activity was higher than CK group. It suggested that He-Ne laser can improve ATPase activity. It indicated that the damage of wheat seedlings induced by UV-B radiation can be repaired partly by He-Ne laser.

The thalassemias are a group of anemias result from inherited defects in the production of hemoglobin. The current techniques for screening and diagnosis of thalassemia are time consuming and complex. A laser tweezers Raman spectroscopy (LTRS) setup was used to trap single erythrocyte from patients with thalassemias and normal donors, and to collect the Raman scatting of trapped cell. Blood samples obtained from 11 patients with non-deletional HbH disease (HbH-CS), 11 patients with β-thalassemia major, and 11 normal controls, were tested. Principal component analysis (PCA) algorithm combined with back-propagation neural network predictive model was performed to distinguish abnormal erythrocyte. The PCA results reveale that the difference between normal controls and HbH-CSs is significant with the predictive accuracy of BP network as high as 97.90 %. The predictive accuracy between normal controls and β-thalassemias major is 90.72 %, and 86.28 % between HbH-CSs and β-thalassemias major. These results tally closely with the corresponding averaged Raman spectra. Under different experimental condition, the predictive accuracy showes similar results. This pilot study can serve as a useful probe for developing a rapid, simple, reagent-free method for distinguishing of thalassemia erythrocytes.

An experimental scheme was established for noninvasively measuring the characteristics of light propagation along human meridian direction. The diffuse emittance of the arm skin along the pericardium meridian and non-meridian directions for 658 nm light radiation were measured. The influence of the light chopped frequency and the meridian block on the detected signal was investigated. Our study suggest that the light attenuation along both the meridian and non-meridian directions conforms to definite law. There is a high significant difference between the propagations along the meridian direction and non-meridian direction (P<0.01). Furthermore, the chopped frequency and the meridian block can affect the detected signal. The diffuse emittance signal decreases with the chopped frequency’s increment in the range of low frequency(10-370 Hz), and the relative difference of detected signal along meridian and non-meridian directions increases with the block force’s increment. These research results are important and valuable for interpreting the human meridian phenomena and the physical-chemical characteristics of acupuncture point and meridian by biomedical optics.

Using a 3D photo-thermal model for selective photothermolysis (SP), the effects of blood vessel parameters, such as blood vessel diameters, locations and numbers, on the photo-thermal interactions during SP were numerically studied. The numerical results show that the thermal damage rate of the targeted blood vessel would be decreased if there are other blood vessels existed in the neighboring region, the dimensions of which are determined by the diameter of laser beam and laser wavelength. Generally, if the other blood vessels are outside the laser beam, or deeper than 1 mm for 585 nm laser, their effects are neglectable. The study can be used for scheming and optimizing the clinical laser treatments.

In order to measure different life-cells with more scattering information of hologram, light propagation models of red blood cell (RBC) and white blood cell (WBC) are built based on their optical characters and the digit holograph function of the VirtualLabTM imitation system. The distributions of cells, scattering phase and their intensity are achieved after using this virtual imitation experiment system according to the digit phase microscopy (DPM) method and its experimental parameters. These distribution characters are studied and it is found that the phase distributions can be used as an important criterion for testing cells, distribution because of their relationship. Comparing the 3-D building method, this cell-constructing method based on the phase analysis needs fewer confine condition and less counting. It provides a breakthrough for developing cell’s measurement in technique and method.

To evaluate the efficacy and safety of CO2 laser sclerectomy with iridectomy (CLSI)as an main initial treatment for diagnosed primary glaucoma, after intraocular hypertension rabbit model is created, right eyes are treated with an improved CO2 laser glaucoma treatment system with self-feedback and left eyes are treated with traditional trabeculectomy. Postoperative anterior chamber reaction, filtering bleb, mean intraocular pressure (IOP), and pathology examination are observed. Anterior chamber reaction of laser group is lower than that of traditional surgery group. On the 14th and 21th days postoperatively, obvious decrease of functional filtering bleb number and increase of mean IOP are found in traditional surgery group . There is statistical significance between these two groups (P<0.05). Compared with laser group, more serious hemorrhage and fiber proliferation, and much shorter lifespan of filtering route are observed in traditional surgery group. CLSI is a safer and simpler operation procedure that effectively reduces IOP with less complications.

The experimental investigation of the fiber Bragg grating (FBG) sensor in monitoring action for the laser thrombolysis is introduced. In laser thrombolysis, the pulsed laser is absorbed by blood, leading to cavitating bubbles. The shock wave is generated during bubble expansion and collapse. With a tunable distributed feed back (DFB) LD laser as the light source and an edge filtering demodulation, the shock wave was measured by FBG based sensing system. In experiment, the peak power of the shock wave response increases with the laser power, and the FBG responsibility for the shock wave in the blood after ablation of clot is similar to that in blood without clot. According to this similarity, whether the clot is ablated or not can be distinguished. In the in vitro experiment, the measured ablation time is 23 s.

By using two-photon excited fluorescence (TPEF) and second harmonics generation (SHG), we imaged fresh ex vivo thyroid tissues, including normal thyroid tissue,nodular thyroid tissue and papillary thyroid carcinoma tissue. As can be seen, the follicles in normal thyroid tissue are in uniform size and shape, while in nodular thyroid tissue the follicles are in different size, and there are abundant substantial cancer cells in papillary thyroid carcinoma. These results are consistent with the corresponding standard H&E histology imagings. Furthermore, the collagen distributions in normal thyroid tissue and nodular thyroid tissue are observed to be different. These results suggest that the two-photon fluorescence microscopy imaging can distinguish, the morphologic differences between normal thyroid tissue,nodular thyroid tissue and papillary thyroid carcinoma tissue in microstructure, and it has the potential to be used for minimal invasive and rapid diagnosis of thyroid cancer.

The seedling of wheat (jinmai 8) was exposed to He-Ne laser (5 mW·mm-2), enhanced UV-B radiation (10.08 kJ·m-2·d-1) and the combined treatment of He-Ne laser irradiation and enhanced UV-B radiation.The research discovers, light absorbability of thylakoid membrane of wheat seedling leaves is decreased by enhanced UV-B radiation, Mg2+-ATPase and Ca2+-ATPase activity are also depressed. Activity of photophosphorylation(PSP), cyclic PSP and non-cyclic PSP, is restrained by enhanced UV-B radiation.The enhanced UV-B radiation causes damage on thylakoid membrane of wheat seedling. But certain amounts of He-Ne laser can partially repair UV-B damage on thylakoid membrane wheat seedling leaves, and reconstruct light absorbability of thylakoid membrane of wheat seedling. Mg2+-ATPase and Ca2+-ATPase activity are also raised. Cyclic PSP and non-cyclic PSP activity is increased by He-Ne laser.The SDS-PAGE result shows that different treatment groups can not induce obvious differences on the polypeptide compositions of thylakoid membrane, which will be reduced by enhanced UV-B radiation,but increased after He-Ne laser radiation.

The radiation damage in EC9706 cells by X-rays was studied. Laser Raman spectrum was used to analyze the change of structure and content of protein, nucleic acid and fat, while EC9706 cells irradiated by X-rays was cultivated for 24 h. The results show that the peak and frequency shifting are different from spectra of the controlled dose and reference groups. The peak in the controlled group spectrum vanishes in some dose groups'. The peak at 1114 cm-1 of ν(C-N) in the main chain of protein disappears in all dose group′s, the peak at 895 cm-1 of ν(Dr) only exists in 8Gy group′s, and the peak at 937 cm-1 only exists in 12Gy group’s. In addition, the C=C vibration peak at 1523 cm-1 β-carotenoid combining cell film only exists in 6Gy group′s. The preferable dose of X-rays can be found by analyzing the variety of the above-mentioned peaks in some dose groups'.

The self-developed swept source optical coherence tomography (SS-OCT) system is reported. Based on a high speed scanning laser source, the system realizes high speed A-scan rate of 20 kHz from 500 Hz A-scan rate of time-domain OCT. To realize linear calibration of wave number space, a pre-calibration method based on the SS-OCT system is used. Because of the non-Gaussian spectrum output of the swept source, a method based on window function is used for spectrum reshaping in the spectrum domain. To eliminate the direct current（DC） and auto-correlation term in the interference spectrum, the common-rejection of balanced detection, and a software method of subtract the mean value were used. The axial and lateral resolution of the SS-OCT system achieves 14 μm and 12 μm, respectively. The ranging depth of the SS-OCT achieves 3.9 mm. High speed optical coherence tomography images of finger-pad organism using the SS-OCT system wera obtained.

This study designed to establish a complete transaction of dorsal corticospinal tract SD rat model and discuss about the effect of low power laser irradiation on neuron regeneration after acute spinal cord jury. 30 SD rats were equally and randomly divided into two groups. Complete transaction of dorsal corticospinal tract was done to each rat. Then,irradiation group was undertaken local consecutive low power laser irradiation 15min after surgery and lasted for 14 days. Compared to irradiation group,there was no postoperative irradiation after surgery in control group. After infusion,1 cm length of spinal cord,which was above and below T8 level,were extracted on the 3rd,7th and 14th day after surgery. Hematoxylin and eosin stain and immunofluorescence stain were use for evaluation. At two weeks after surgery,the value of gial scar area was less than that of control group with statistically significant differences. There was intensive expression of glial fibrillary acidic protein (GFAP) and Chondroitin Sulfate (CS56) around the injury area in control while sparsate distribution of GFAP and CS56 was found in irradiation group. An amount of fibriform Neurofilament (NF) expression associated with regularly Growth Associated Protein 43 (GAP43) expression were located around the injury area,However,scrambled and slight GAP43 and NF expression were found in control. The result of our study showed that low power laser irradiation can improve regenerate of axon and decrease formation of gial scar area during the acute stage of spinal cord injury.

This paper reports the mechanism of two-photon absorption photopolymerization and the femtosecond laser technology used for biocompatible materials ORMOCER three-dimensional micro-nano processing.Two-photon absorption photopolymerization was achieved in ORMOCER resin, the resolution reached 0.5 μm less than the diffraction limitation. The mathematical expression of two photon photopolymerization threshold is derived, the effect of the scanning speed V and the laser power P on the transverse size is studied. Using two-photon femtosecond laser micro-processing technology fabricates a typical microbial devices such as micro-well array,micro-pole-array, and photonic crystal micro-biological scaffold.

Speckle noise significantly limits the information content extraction provided by optical coherence tomography (OCT). Therefore speckle reduction is an important issue in OCT imaging. Using a method of regularization by minimizing Csiszar’s I-divergence, we derive a method of speckle minimization. This method can not only produce an image data that is consistent with the known data but also extrapolate additional detail. This algorithm is used to process the OCT image of the human finger. The results show that this method of speckle minimization can significantly reduce speckle and increase the signal-to-noise ratio, while preserve edge sharpness.

To explore a new method to dignose methemoglobin, micro-Raman spectroscopy was used to investigate the interaction of sodium nitrite and oxyhemoglobin in aqueous solution, with 514.5 nm exitation. Hemoglobin was obtained from the healthy adult. The results show that the inensity ratio of the oxyhemoglobin marker band 570 cm-1 to the aquomethemoglobin marker band 495 cm-1, and that of low spin state marker band 1586 cm-1 to the high spin state marker band 1555 cm-1 decrease during the interaction. The bands sensitive to the oxidation state shift to higher frequency. This work indicates that micro-Raman spectroscopy could monitor the bioeffects of sodium nitrite on the oxyhemoglobin, and distinguish hemoglobin and aquomethemoglobin. As a new method to detect methemoglobin, micro-Raman spectroscopy may have great potential applications in the diagnosis of methemoglobinemia.

Single-mode fiber-designed optical coherence tomography (OCT) system is developed and applied in ophthalmic imaging. Images with high signal-to-noise ratio, high resolution and large image depth, are achieved by the developed system. The calibrated axial resolution and transversal resolution are 9 μm and 10 μm, respectively, and the maximum depth range is 3.4 mm. Comparison between experimental results and Zeiss OCT Ⅲ are presented. The results show that the proposes OCT system can image not only the layers of retina , but also the layers and vas of choroid which cannot be obtained by Zeiss OCT Ⅲ.

This paper evaluates the influence of different defocus irradiation conditions on bone hard tissue ablation by pulsed CO2 laser. Bovine shank bones in vitro were used in this experiment which were put on a PC-controlled motorized linear drive stage and moved repeatedly through the focused beam. Work distance was adjusted to obtain a beam spot size of about 510 μm on tissue sample before and after focus plane respectively. The wavelength of pulse CO2 laser was 10.64 μm, pulse repetition rate was 60 Hz, and the energy density is 5～45 J/cm2. The moving speed of the stage was 20 mm/s, scanning times was 6. After irradiation, the incision morphology was observed by naked eye and confocal microscopy. The geometry measurement of the incision was also taken. It was showed that pulsed CO2 laser can be used to cut hard bone tissue, and the defocus irradiation condition has an important influence on ablation effect. In order to obtain a narrow-and-deep incision and high ablation rate, one can locate the beam focus slightly under the bone surface.

The wheat seeds are irridated by CO2 laser with power of 20.1 mW/mm2 for 3 min. When the wheat seeds grow about 12 days, the seedlings are treated with the 10% polyethyleneglycol 6000 (PEG6000) stress. And the effects of NO on the CO2 laser pretreatment inducing drought tolerance are studied through sodium nitroprusside and hemoglobin added with NO. The results show that laser pretreatment and NO donor sodium nitroprusside (SNP) could decrease the concentration of malondialdehyde (MDA) and increase the activities of superoxide dismutase (SOD), peroxidase(POD), catalase (CAT) and the concentration of chlorophyll a, chlorophyll b and root dry weight in the wheat seedlings with drought tolerance. But the promotive effect of laser pretreatment induced drought tolerance in wheat seedlings was not effectively reversed by the addition of hemoglobin (NO scavenger).

Medical laser has been applied more and more broadly in bio-tissue cutting, but the efficacy and the side effect have never been standardized at parameters level, depending highly on the experiences of the operator, which causes disadvantage for the spread of this technology; while the choice of the technical parameters of the laser form a crucial factor in the developing of the product. To seek for the optimized parameters, we studied the interaction between the tissue such as the parenchyma of the dog′s kidney and Ho∶YAG laser at different energy densities (50～400 J/cm2), in a circumstance of operation simulated via some extra corporeal animal experiments. We got the statistical results of the interaction, the optical micrograph of the slice and the record of the remained thermal effects. We analyzed the influencing factors of the interaction and the evolution of the remained thermal effects. A peak-value exists at about 290 J/cm2 on the unified curve of the efficacy, which can be used as the recommended value in standardizing. The analysis of the influencing factors and the remained thermal effects brings reference to the improving on the medical laser devices.

Based on the eye model of Kooijman, the effects of the reflection losses and nonnormal incidence of laser on the human eye’s visual quality after refractive procedure on a cornea were analyzed by comparing the J. R. Jimenez’s theory and Munnerlyn’s. The reflection losses and nonormal incidence on the anterior cornea lead to the under-correction of the post-surgery eye. With the 6 mm diameter of the optical zone, when the refractive error of the eye before surgery is -9D, the under-correction is only -0.6D. The corneal asphericity after refractive surgery increases for myopia. With the increase of the refractive error before refractive surgery, the asphericity of the anterior cornea changes from negative to positive, which leads to the increase of the spherical aberration. There is no large difference between the asphericities obtained by Munnerlyn’s theory and Jimenez’s. The diameter of the optical zone has little effect on the post-surgery p-value.

This paper studied the biophysics’ index of low power laser irradiation on human’s red blood cell (RBC) to find the primary factor that affects biophysics of RBC. The blood cells of the deformability health human deposited in 4 ℃ for 48 h are used as samples, and the effects of low power laser irradiation on these samples are investigated. These samples are divided into two groups. One group is irradiated for 30 min under the laser with the powers of 2 mW, 4 mW, and 8 mW. The RBCs in the other group are doped with PBS with the same concentration. After centrifugating, they are processed in the same way. The results show that the characteristics of the blood cell irradiated by laser are less than the whole blood. Our study indicates that the magnify effects of the human’s red cells’ membrane are important to the rheology characteristic of the blood.

Cryogen spray cooling (CSC) is an effective cooling technique used for laser treatment of port wine stain (PWS). The cooling process involves complex droplet evaporation, strong convective heat and mass transfer, therefore a deep understanding of spray characteristics is essential to optimize the nozzle design and improve the cooling efficiency of the spray. This paper presents a theoretical model to describe the equilibrium evaporation process of a single droplet in cryogen spray. The model considers mass transfer through mass transfer number method, the momentum transfer by selecting the suitable empirical correlation of drag coefficient, and heat transfer by taking into account the droplet evaporation and convective effect with ambient air. Through simulating the cooling stage of a hanging water droplet and the temperature variation of cryogen droplets in cryogen spray, the model is validated by the reasonable agreement with the experimental measurements. Then a parametric study of the influences of initial diameter and velocity on the droplet evaporation is carried out, which states that an effective analysis method can be provided by the proposed model to guide the CSC of laser therapy.

The low luminescence of serum is tested with the low luminescences detection system. In the experiment the low luminescence of serum of the hyperglycemia, hyperlipoidemia, and normal man are tested respectively, and the laws of serum radiation intensity with variation of blood sugar and triglyceride concentration are studied. And the image of the low luminescence of serum is analyzed quantitatively with self-programmed software. The experimental result shows that the serum radiation intensity increase synchronously with blood sugar concentration linearly. The gray threshold of triglyceride luminescence image also increases with triglyceride concentration, but it is not obviously as the former one. So the blood sugar concentration can be estimated by the serum luminescence intensity, and it is effective. It provides experimental foundation for the medical diagnose.

The effects of optical properties of myocardium tissue due to heating in the visible and near-infrared spectral range were investigated. A spectrophotometer was used to measure the diffuse reflectance and total transmittance of the tissue samples, and the inverse adding-doubling (IAD) method was applied to assess the absorption coefficients, the reduced scattering coefficients and the optical penetration depth of tissue from the measurements. The results of measurement show that the absorption and reduced scattering coefficients and optical penetration depths of myocardium tissues vary with the change of irradiation wavelength. There are a positive peaks at 550 nm for the absorption coefficients of both native and thermocoagulated (treated with 80 ℃) myocardium, and the peak values for native and thermocoagulated myocardium are 0.74 mm-1 and 1.16 mm-1, respectively. There is a positive peak at 550 nm for the reduced scattering coefficients of native myocardium and the peak value is 0.25 mm-1, whereas the peak disappears after myocardium tissue treated with high temperature. Further more a new increase appears at the wavelength range of 590～625 nm. The absorption coefficient of myocardium tissue is not significantly changed by treating with lower temperature but increases slightly with higher temperature. The reduced scattering coefficient of myocardium tissue is significantly increasing with the increase of treating temperature. And the optical penetration depth of myocardium tissue is significantly decreasing with the descrease of treating temperature.

In order to increase the signal-to-noise ratio (SNR) and improve the detection sensitivity of the optical coherence tomographic (OCT) system, the main noise sources in the OCT system are analyzed in detail. A theoretical noise model is then proposed which may be used to analyze the effect of different parts of OCT system. Based on the theoretical results, the performance of an OCT imaging system is analyzed. Through measuring the noise level of the system, the experimental model of the system noise is obtained, and then it is used to correct the theoretical analysis results. Based on the above analysis, the imaging performance of the OCT device is optimized. The axial resolution of 16 μm, and the detection sensitivity of -90 dB have been obtained.

To test the contribution of the direct effects of photodynamic therapy (PDT) on tumor cells, we examined the immunogenicity of PDT-generated murine tumor cell lysates in a preclinical vaccine model. Sixty Kunming mice (H22 tumor host) were divided into two groups randomly and equally. Six to twelve-week-old Kunming mice were vaccinated intradermally on the right shoulder with 50 μL lysates (3×105 cell equivalents) for experimental group or medium control for control group every three days during two weeks. The mice rested a week and then inoculated on the flank with 1×106 tumor cells harvested from exponentially growing cultures. And then we compared antitumor rate, survial rate and relevant indicators of immunology between two groups. PDT vaccines could inhibit the tumor growth rate compared to the contrast group. The tumor inhibition rate of PDT vaccines group was 60% and long-term available. The survival rate of PDT vaccines group at 100 day was 56% which was significantly higher than contrast group. Our studies suggest that PDT-generated vaccines could effectively inhibit tumor growth, improve survival rate of mice in experimental group, and enhance antitumor immune response significantly. PDT-generated vaccines may have well clinical potential as an adjuvant therapy.

A newly developed single-mode fiber-designed optical coherence tomography (OCT) system is built based on low coherence interferometry and optical heterodyne detection. A broadband infrared optical source centered at 840 nm with a bandwidth of 50 nm is used as the system source. A stable high carrier is generated by Fourier-domain rapid scanning optical delay line (RSOD) as phase modulator. With this developed system, two-dimensional (2D) cross sectional images of tissues in vivo are reconstructed. The experiment results indicate that the system has an axial resolution of 6.7 μm, approaching the ideal resolution, and transversal resolution of 4.7 μm in air. The depth imaging range is above 3 mm in air. Although less than 300 μW optical power is incident on the sample, the system sensitivity is above 88 dB. With the same incident power on the sample, an image of the same sample (fresh orange) with a 1310 nm OCT system is also provided. The qualitative comparisons between the two system at different central wavelengths demonstrate the impressive potential of 840 nm OCT system to perform eye posterior structure imaging. The image of the animal retina in vivo is presented.

The process of thermal denaturation of the albumin was studied using dynamic speckle method based on wavelet entropy. At first, the dynamic speckle pattern sequences generated by albumin colloid during denaturing were acquired using charge-compled device (CCD) camera. Using the speckle sequences, the time history of speckle patterns (THSP) were generated. And then, with the wavelet entropy as a parameter, each row of THSP was separated into eight time windows which were decomposed by db4 orthogonal wavelet family into three levels . Thus a three-dimensional matrix of 256×256×8 of wavelet entropy was generated. Finally, this matrix was grayed into eight 256×256 patterns, which made the change of dynamic speckle signals visulized. According to the patterns, the movement properties of the protein molecule ensemble were analyzed during thermal denaturation of the albumin. The results show that this method is effective to analyze the process of movement and aggregation of protein molecules quantitatively. Experimental results prove that this method is a useful tool to investigate the motion of particles in solution.

In order to discriminate and identify phytoplankton of different divisions and genuses, coiflet2 (coif2) wavelet function was utilized to extract the characteristics of the three-dimensional (3D) fluorescence spectra of 12 phytoplankton species belonging to 9 genuses of 4 divisions. The third scale vectors selected as the discriminating characteristic spectra, obviously express the distinguish characteristics of different genuses and divisions. The results of Bayes discriminant analysis showed that these characteristic spectra had average discriminating rates of 99.0% and 97.4% at the division and the genus level, respectively. Reference spectra were obtained from these characteristic spectra by cluster analysis. A fluormetric method was established by multiple linear regression resolved by the nonnegative least squares. These reference spectra identified the single species added with 10% and 20% ratios of random noise with the rates of more than 98.0% and 85.0%, respectively, at the division and the genus level. All the dominant species of the phytoplankton mixtures could be identified 100% at both the division and the genus level.

To explore the feasibility of fabricating nasal prosthesis with selective laser sintering method, a digital model of nasal prostheses for patients was produced through the integration of structural light scanning and CAD technique. A wax model of nasal prostheses was fabricated with selected sintering method under special manufacturing parameters. The result of accuracy evaluation and clinical try-in showed a satisfying shape of wax model and a comparatively high precision. Then the wax pattern was processed into the definitive nasal prosthesis and a clinically satisfying effect was achieved. Comparing with conventional manual methods, the new fabricating method shortens time and simplifies manufacturing steps. This digital and model-free manufacture provides a new method for the automatic manufacture of maxillofacial prostheses, and has potential for the clinical application in the future.

To study the mechanism of helium neon laser promoting blood vessel rebuilds in periodontium of rabbits experimental tooth movement in rabbits, He-Ne laser with the wavelength of 632.8 nm and power of 20 mW was used to irradiate periodontium of experimental tooth movement of rabbits. The result was analysised by immunohistochemistry dyeing and image analysis. The experiment show that the vascular endothelial cell growth factor (VEGF) R-2 expression where the low level laser irradiation, regardless of comparison in the pressure zone or the tension area, appears earlier, have higher peak power and longer time than it does in side irradiating. After stopping the irradiation, the expression level of the irradiation side of the VEGFR-2 is still higher than the comparison side. It shows that the biologic effect still continue after stopping the low level laser irradiation. The result indicates that the low level laser irradiation can promote the VEGFR-2 expression effectively, thus promotes the vascularization of orthodontic dental capsule and the rebuilding of bone.

The optical effect of laser on protecting wheat from ultraviolet-B (UV-B) damage was tested. A patented instrument, coherent-to-incoherent optical converter, was employed to transform semiconductor laser into incoherent red light. The wavelength, power and spot diameter of incoherent red light are the same as that of semiconductor laser. A semiconductor laser and incoherent red light with wavelength of 650 nm and power density of 3.97 mW/mm2 directly irradiated the embryo of wheat seed for 3 min respectively, and when the seedlings were 12 days old they were irradiated by 10.08 kJ/m2 UV-B radiation for 12 h in darkness. Changes in the concentration of malondialdehyde (MDA), UV-B absorbance compounds, soluble protein, chla, chlb, the activities of peroxidase (POD), catalase (CAT), superoxide dismutase (SOD), and the growth parameters of seedlings (root length, root dry weight) were measured to test the optical effect of laser. The results showed that semiconductor laser pretreatment could enhance the SOD, POD and CAT activity, UV-B absorbance compounds, soluble protein, chla and chlb concentration, and root length, while incoherent red light pretreatment could not. When the cells of plant were irradiated by UV-B, concentration of cyclobutane pyrimidine dimers (CPDs) in wheats leaves was detected by enzyme-linked immunosorbent assay (ELISA) method, incoherent red light treatment could not eliminate active oxygen and prevent lipid peroxidation in wheat. The results also demonstrate that the plant DNA was injured by UV-B radiation and the semiconductor laser irradiance has the capability to protect plant from UV-B-induced DNA damage, while the incoherent red light could not. It is suggested that the potential mechanism is not the optical effect of laser treatment.

Coronary artery stent is an important mechanical device designed to open arteries that have been occluded. In this paper, the processing techniques including output power, frequency, cutting speed, pulse width and assistant air pressure, which influence the quality of the coronary artery stent, have been studied with the fiber laser precision cutting system. The best processing techniques have been gained with the analysis and experiments. The high quality coronary artery stents have been cut with the output power of 7 W, pulse length of 0.15 ms, repeat frequency of 1500 Hz, scanning speed of 8 mm/s and oxygen gas pressure of 0.3 MPa.

In the present experiments,pure titanium specimens fabricated by laser rapid forming (LRF) have been investigated, and based on the national standards (GB/T 13810-1997, GB/T 16886.5-2002), the mechanics properties, microstructure and cytotoxicity experiments were tested. The results show that tensile strength is 475 MPa, yield strength is 383 MPa, elongation is 27%, Vickers hardness is 188.4～206.3, and Young′s modulus is 97.54 GPa. In vitro experiment, the cytotoxicity of LRF titanium specimens is grade 0. These data confirm that the LRF pure titanium can be efficient for surgical implants.

The optical properties and differences for normal human stomach mucosa/submucosa tissues in vitro at 488 nm, 514.5 nm, 532 nm, 630 nm and 632.8 nm wavelengths of laser were determined in this paper. Measurements were performed using a charge coupled device (CCD) detector, and optical properties were assessed from the measurements using the spatially resolved reflectance, and nonlinear fitting of diffusion equation. The results of measurement showed that absorption coefficients, reduced scattering coefficients, optical penetration depths, diffusion constants, diffuse reflectance and shifts of the diffuse reflectance of the tissue samples at five different laser wavelengths vary with a change of laser wavelength. The maximum absorption coefficient for tissue samples is 0.482 mm-1 at 532 nm, and the minimum absorption coefficient is 0.224 mm-1 at 632.8 nm; the maximum difference in the absorption coefficients is 115% between 532 nm and 632.8 nm, and the minimum difference is 1.90% between 488 nm and 532 nm. The maximum reduced scattering coefficient for tissue samples is 5.93 mm-1 at 488 nm, and the minimum reduced scattering coefficient is 3.87 mm-1 at 632.8 nm; the maximum difference in the reduced scattering coefficients is 53.2% between 488 nm and 632.8 nm, and the minimum difference is 3.25% between 514.5 nm and 532 nm. The maximum optical penetration depth for tissue samples is 0.612 mm at 632.8 nm, and the minimum optical penetration depth is 0.341 mm at 488 nm. The maximum diffusion constant for tissue samples is 0.084 mm at 632.8 nm, and the minimum diffusion constant is 0.055 mm at 488 nm. The maximum diffuse reflectance for tissue samples is 0.356 at 630 nm, and the minimum diffuse reflectance is 0.271 at 532 nm. The maximum shift of the diffuse reflectance of the oblique incidence for tissue samples is 0.153 mm at 632.8 nm, and the minimum shift of the diffuse reflectance of the oblique incidence is 0.100 mm at 488 nm. It is obvious that there were distinct differences in the optical parameters for normal human stomach mucosa/submucosa tissues at five different laser wavelengths.

A laser power/energy meter which is designed based on laser induced thermoelectric voltage (LITV) effect was reported. The laser power/energy meter can not only measure and record the energy of every input laser pulse and the total real-time energy, but also can record the response waveform of every input laser pulse. It realize the real-time controlling for laser energy. It was used to simulating experiment for 248 nm excimer laser. The result show that the relative standard deviation (RSD) of the laser output energy is 8.6%～10.7% with repetition frequency. And under the simulating setup parameters of refractive surgery, 193 nm excimer laser was measured, and its RSD is 8.3%. This kind of laser power/energy meter would be very significant in cornea refraction operation.

The seedlings of wheat (Jinmai 8) were exposed to He-Ne laser with 5 mW·mm-2 power density, enhanced ultraviolet-B radiation (UV-B) (10.08 kJ·m-2·d-1) and the combination of He-Ne laser and enhanced UV-B radiation respectively for 5 days. Changes about production rate of superoxide anion, malondialdehyde (MDA) content, ultraviolet absorption value and conductance of exosmic fluid of wheat seedlings, content of soluble protein and chlorophyll were measured to analyze the repair role of He-Ne laser irradiation. The results showed that He-Ne laser irradiation on the wheat seedlings led to the decrease of the production rate of superoxide anion, MDA content and ultraviolet absorption value and conductance of exosmic fluid of wheat seedlings. The content of soluble protein and chlorophyll increased to 76.66% and 1.79 mg/g respectively. It suggested that those changes about production rate of superoxide anion, MDA, ultraviolet absorbing value and conductance, soluble protein and chlorophyll were related to the repair capacity of the wheat seedings. Therefore, the damage of wheat seedlings induced by enhanced UV-B radiation can be repaired partly by He-Ne laser.

Acutely isolated rat hippocampal CA3 pyramidal neurons were irradiated with a semiconductor laser of 650 nm wavelengh and 5 mW power, and properties of delayed rectifier potassium (K+) channel were studied using the whole-cell patch clamp technique. The experiment indicated that low level laser reversibly reduced the amplitudes of IK in a time-dependent and voltage-dependent manner. The percentage of inhibition was up to 34.54%±3.22% (n=15) in irradiating 5 min. The maximum activated current densities of control group, irradiation group and restoration group respectively were 429.78±41.40 pA/pF, 283.26±39.62 pA/pF (n=10, P0.05). Laser irradiation significantly affected the activation process of IK. The half-activation voltage and the slope factor of the activation curves were also changed by the laser′s exposure. The half-activation voltages of control group and irradiation group were 5.74±1.56 mV and 20.98±8.85 mV (n=10, P0.05) respectively. The results show that low level laser can change the properties of delayed rectifier K+ channel. Therefore, repolarization process of action potential is affected. Further, physiological functions of neurons are adjusted, which might contribute to the restoration and regeneration of injured neurons.

The control effects of the main insect of fruits—drosophila melanogaster were studied with the semiconductor laser in this paper. The experiment was designed with response surface method to investigate the biological effects on drosophila melanogaster with different laser power and irradiation time. The results showed that the death rate was above 99% to the larva of drosophila melanogaster under the conditions of laser power of 60 mW and irradiation time of 1282 s, with semiconductor laser at wavelength of 650 nm. At the same time, the weight of drosophila melanogaster was reduced, and the required eclosion time was decreased. Therefore, the semiconductor laser has strong biological effects to larva of drosophila melanogaster. However, when the power was below 40 mW, the laser light has the effect of promoting the growth of drosophila melanogaster. The experiment demonstrated that drosophila melanogaster did not show anti-laser effects in the third generation under the same experimental conditions compared with the control groups, it is suggesting the possibility of the semiconductor laser application on pest control of fruits.

The technology of fingerprint identification is a convenient, reliable, noninvasive and cheap scheme for biometrics. A method that adopts surface plasmon resonance imaging (SPRI) to collect fingerprints utilizing surface plasmon resonance (SPR) phenomenon is put forward to improve the quality of images in this paper. The principles and the structure of SPRI system are introduced. SPR is stimulated by a Kretschmann prism couple configuration. The cover glass coated with a 50 nm gold film serves as a sensor chip. The fingerprint is then imprinted on the gold film. Polarized monochromatic light is projected on the sensor through the prism, where the SPR phenomenon occurs. The reflected fingerprint image is collected by CCD. The images are collected by SPRI and conventional optic method for the same fingerprint, two different contrast gradients in which the fingerprint ridges are compared with the valleys of the main parts of the two images are 0.2014 and 0.0516 respectively. The contrast and clarity of the image collected by SPRI are much improved.

Based on the computer aided design (CAD) digital base of complete denture model, a titanium base was made with the RS-850 laser rapid forming system, which processing parameters were suitable. The method made the Ti-base faster comparing with the traditional one, and the shape of the complete denture base was very well. The success development of the titanium base provided a new method for the automatic manufacture of titanium prosthetic replacement, and would make the foundation for the clinical application in the future.

The dependence of optical clearing on properties of the different tissue structures is investigated in order to better know the clearing mechanisms and effective clearing approach. Two typical tissues, muscle and epithelial, have been chosen as the targets and the effect of optical clearing has been comparatively studied by optical coherence tomography (OCT) and near infrared spectroscopy (NIR) with the clearing agent glycerol used. The results show that the improved imaging depth and contrast among different layers in the porcine skeletal muscle and stomach mucosa are visualised with the OCT assessment. The overall increases in light transmittance in the muscle tissue and the stomach mucosal tissue after 30 min treatment are observed to be approximate 21% and 16%, decreases in diffuse reflectance are 33% and 21%, respectively, with the quantitative measurement of NIR. The clearing progress of each tissue type as a function of time corresponds very well with the respective loss in water dynamics shown by the near infrared spectra: early rapid transport, mid-linear and slow exponential diffusion for muscle tissue, and contrarily for stomach mucosa with an early very slow transport and later linear increasing efflux. The different permeabilities of muscle tissue and mucosal tissue are thought to be accountable for the difference in clearing effect between the two tissues. These observations confirm expectation that optical clearing is dependent on tissue structure in an explainable manner.

A measurement system is introduced using the technologies of fiber-optic sensing, dispersion of grating and multi-channel image sensing based on fluorescence mechanism of pesticides. The system adopts a pulsed xenon lamp as an excitation light source, chooses optical fibers to transmit and detect fluorescence, implements dispersion of fluorescence with a small-sized flat field grating spectrometer and conducts data gathering and conversion with a high speed signal processing module. A full fluorescence spectrum of pesticides within a single exposure can be gotten. Moreover, it is used to conduct the measurement of fluorescence characteristics of carbaryl and carbofuran. The results show that the pesticides can emit fluorescence of 340～750 nm as excited by ultraviolet (UV) light of 319 nm,and the system has a good linear relationship in the range of 0.003～0.1 mg/L and the minimum detecting limit is 0.003 mg/L. At the same time, the instrument is also be applied to detect concentration of the trace pesticides in Chinese cabbages,the recovery may be closed to 100%.

Treatment of port wine stain (PWS) by photodynamic therapy (PDT) has been under development over last years. To study the acting factors on vascular selectivity of photodynamic and help the doctor confirm therapy plan in clinic, the mathematics modeling of photodynamic therapy treating port wine stain is built. The modeling include light distribution in tissue, production of singlet oxygen, diffusion of photosensitizers and photobleaching. Using the model, a problem of therapeutic effect in clinic is analyzed and a new therapy scheme is recommended. The scheme is proved to be effective in the clinic experiment.

Pathological changes and thermal coagulation of human liver tissue induced changes of the optical properties of liver tissue at 532 and 1064 nm wavelengths of laser in vitro. The measurements were performed using a double-integrating-sphere setup, and the optical parameters were assessed from these measurements using the inverse adding-doubling method (IAD). The results of measurement showed that the absorption coefficients of normal liver tissues at 532 and 1064 nm are significantly bigger than those of liver tumors at the same wavelength respectively. When liver tissues were coagulated by heat, the absorption coefficients of normal and tumorous liver tissues of thermal coagulation at 532 nm significantly increase, the absorption coefficient of normal liver tissues of thermal coagulation at 1064 nm significantly decreases, and the absorption coefficient of liver tumors of thermal coagulation at 1064 nm significantly increases. The scattering coefficients of normal liver tissue at 532 and 1064 nm are significantly smaller than those of liver tumors at the same wavelength. When liver tissues were coagulated by heat, the scattering coefficients of normal and tumorous liver tissue of thermal coagulation significantly increase. The anisotropy factors of normal liver tissue at 532 and 1064 nm are obviously bigger than those of liver tumors at the same wavelength respectively. When liver tissues were coagulated by heat, the anisotropy factors of normal and tumorous liver tissue of thermal coagulation at 532 and 1064 nm obviously decrease.

To analyze the effects of applicator types and emitting characters on laser-induced interstitial thermotherapy (LITT), based on an optical-thermal mathematical model considering the dynamic changes of physical properties during laser heating, the sizes and shapes of thermal damage regions for bare fiber tips and diffuse applicators were numerically calculated and compared. The effect of the un-uniform emitting radiation of practical diffuse applicator on the thermal damage region was also analyzed numerically. The numerical results showed that the thermal damage region with diffuse applicator was much larger than that with bare fiber for long time heating. The thermal damage region was not spherical symmetry about the fiber tip for bare fibers while approximately ellipsoidal for diffuse applicators. The numerical results also showed that the thermal damage region was not sensitive to the un-uniform emitting radiation of practical diffuse applicators. Applicator types and emitting characters significantly affected the thermal damage regions during laser-induced interstitial thermotherapy.

In order to explore the possibility of photodisruption in rabbit sclera by femtosecond laser and to seek the appropriate ways of incision and relevant parameters, femtosecond laser (800 nm/50 fs) with different pulse energies was applied to irritate rabbit sclera in vitro. By moving a three-axis, computer-controlled translation stage to which the sample was attached, femtosecond laser could achieve three types of incisions, including transscleral channel, snake pattern and linear cutting. The irritated sclera was observed by light microscopy and scanning electron microscopy (SEM). In comparison with femtosecond laser, Nd:YAG laser was used as control. It was shown that through a 0.2 numerical aperture (NA) objective lens, femtosecond laser with the power intensity larger than 9.55×1014 W/cm2 and the pulse energies ranging from 37.5 to 125 μJ could achieve cuttings with the depth from 30 to 70 μm after linearly scanning on the sclera at the speed of 0.1 mm/s. Whereas, it failed to make any photodisruption if laser power intensity was below 7.96×1014 W/cm2 or the pulse energy was less than 31.25 μJ under the same condition. Comparing with Nd:YAG laser, the inner wall of channel was smoother and the damage to surrounding tissues was slighter by femtosecond laser. The high precision and minimal damage to surrounding tissues with femtosecond laser predicted its potential use in the treatment of glaucoma.

There have been controversial reports on photobiomodulation on cartilage healing so that the research on the potential effect of low intensity He-Ne laser irradiation (HNI) on the proliferation and variation of rabbit cartilage cells in vitro was systematically done in this paper. The chondrocytes isolated from the cartilage sample of 3-week-old New Zealand white rabbits were cultured with newborn calf serum (NCS) at 0%, 2.5%, 5%, and 10%, irradiated by HNI at 5.74 mW/cm2 for 2, 8, 16, 30 and 45 min per day for 6 days, and then incubated till the 13th day. The proliferation and collagen synthesis were assessed by XTT assay and hydroxyproline (Hrp) content measurement, respectively. The DNA expression was observed by acridine orange stain and confocal laser scanning microscope. The chondrocyte morphology and ultrastructure have been observed on the 9th and 13th day after the first HNI by scan electron microscope. There is no significant photobiomodulation (PBM) on the proliferation of the chondrocytes (PPC) cultured with NCS at 10%. There is PPC cultured with NCS at 2.5% or 5%, and the effects are significant when the cells were irradiated by HNI for 16, 30 and 45 min, respectively, among which the radiation time 30 min corresponds the optimum dose 9.42 J/cm2. Hrp secretion increased steadily with days in NHI group. When the photobiomodulation is significant, the chondrocyte DNA expression was significant, and its morphological characteristics have no significant differences from the one cultured with NCS at 10%. There might be photobiomodulation on the proliferation of the chondrocytes cultured in nutritional deficit condition and irradiated by HNI at limited dosage, which is of clinic importance.

For the development of novel tetra-substituted aluminum phthalocyanine used as photodynamic therapy (PDT) photosensitizer with good photodynamic anticancer activity, tetraamino-, tetraacetamido-, tetrapropanamido- and tetrabutanamido-aluminum phthalocyanines are synthesized by phthalic anhydride-urea method with 4-nitro phthalic acid as preactant. The structures of these aluminum phthalocyanines are characterized. Their fluorescent spectra and acute toxicity are also measured. Meanwhile, their photodynamic anticancer activities are determined. As a result,the aluminum phthalocyanines are innoxious to mice. When 20 mg/kg aluminum phthalocyanines are injected to S180 sarcoma-bearing mice, the sensitizers show that the rates of inhibitory to S180 sarcoma are 44.96%, 45.87%, 45.62% and 48.65% respectively,which are in little difference according to the order of tetraamino-, tetraacetamido-, tetrapropanamido- and tetrabutanamido-phthalocyanine aluminum, respectively. While the concentration of injecton is raised to 40 mg/kg, the rates of inhibitory are 39.16%, 42.81%, 40.56% and 51.82% respectively for the same order. In this condition, tetrabutanamidophthalocyanine aluminum shows the highst PDT anticancer activitiy.

Laser speckle contrast imaging (LSCI) technique is a new modality to monitoring blood flow dynamics with high spatio-temporal resolution. It records the full-field spatio-temporal characteristics of microcirculation without the need of scanning in real time. In this study, an in vivo model of chick chorioallantoic membrane (CAM) at embryo age (EA) of 10 days, was observed following photodynamic therapy (PDT) irradiated by semiconductor laser (λ=656.5 nm) whose light intensity incident on the treatment site was maintained 40 mW/cm2 using the photosensitizer of pyropheophorbide acid (Pyro-acid). The changes of vessel structure and blood flow velocity were recorded respectively. This study shows that LSCI can assess the efficacy of peripheral vessel damage of tumor in PDT by monitoring changes of vessels structure and blood flow velocity.

Photodynamic therapy (PDT) based on topical application of photosensitizers has been under development over last years. Typical application of photodynamic therapy is treatment of port wine stain (PWS). The dosimetry for topically administered photosensitizers must take an inhomogeneous drug distribution into account together with the conventional parameters such as optical scattering, absorption, and photobleaching. To study the acting factors on vascular selectivity of photodynamic therapy, the mathematic modeling of vascular selectivity of photodynamic therapy was achieved. The singlet oxygen distributions in tissue were simulated with Monte Carlo simulated light distribution. Effect of different photobleaching velocity was discussed. The simulated results indicated that faster photobleaching velocity was helpful to protect the epidermis and dermis. These results were useful for the application of photodynamic therapy in treatment of port wine stain.

With an effort to understand the influence of permeation characteristics of hyperosmotic agents on tissue clearing progress and to look for effective concentrations that minimise the side effect for clinical applications, porcine stomach tissues (mucosa) applied with a mixed solution of glycerol and dimethyl sulfoxide (DMSO) are investigated with near-infrared reflectance spectroscopy and optical coherence tomography. Four solutions of 80% glycerol, 50% DMSO, 50% glycerol with 20% DMSO (GD1) and 30% DMSO (GD2) are studied, respectively. The significant improvement in light transmittance and thus enhancement of light penetration through tissue are demonstrated for all solutions. The development and effect of optical clearing accomplished by the four solutions in an increasing order for 50% DMSO, 80% glycerol, GD1, and GD2 are corresponding well to the rate and degree of water loss induced by the four solutions, which are in the same increasing order.

A Monte Carlo model was developed to simulate laser energy transport in biological tissues photon-number-independently and mesh-independently for laser-induced interstitial thermotherapy (LITT). In addition, laser transport characters in human liver tissue and prostate tissue at 1064 nm and 850 nm as well as its main influential factors were analyzed based on the present model. The numerical results showed that the energy deposition depended paramountly on penetration depth in radial direction and on both penetration depth and active emission length in axial direction.

Based on the experiment of fluorescence spectra of thioredoxin reductase (TrxR) from human brain by the excitation of ultraviolet light (UV-light), this paper studies the spectral characteristics and their origins. The experimental results show that, under the excitation of UV-light, TrxR solution emits spectra of region from 280 nm to 720 nm, including two wider bands and many sharper peaks. The wider bands and the sharper peaks represent different tendency along with the change of solution concentration. According to the theory of conversion of internal energy and resonant Raman scattering, the theoretical analyses of TrxR fluorescence spectra are educed. The results indicate that the wide band with the peak locating at 336 nm is the fluorescence from tryptophan in TrxR and the sharper peaks mostly come from the resonant Raman scattering of TrxR. These researches on the emission spectra of TrxR solution may represent an effort to better understand the conformation, structure and vibration of TrxR molecule.

Diffuse reflectance of tissue close to source about 1 transport mean free path (MFP) can be analyzed by P3 approximation theory, the light distribution of this area is dependent on scattering phase function of tissue. The influence of the structure factor (α) of the combined phase function on the diffuse reflectance light distribution close to source is studied in this paper. The research shows that when the transport MFP is kept constant, the light distribution close to source changes with the anisotropy factor g, but almost does not change in the region of the diffusion approximation; the influence of α on the diffuse reflectance is much more than the influence of the high-order moments of phase function on it. The research is very valuable for the in vivo measurement in endoscopic mode or in superficial tissue based on the spatial-resolved diffuse reflectance.

Various phase-changing thermal effects, i.e. evaporization, carbonization and melting, occur sequentially in the biological tissue irradiated by high-intensity laser. According to this practical thermal effect, a new heat transfer model for laser-tissue thermal interaction is proposed. In the model two heterogeneous tissues, i.e. carbonization layer and bio-tissue layer, are considered and two different phase-changing interfaces are introduced. Some parameters such as the temperature and moving velocity on the interfaces as well as the carbonization depth are obtained by numerical solution. The relationship between these parameters and the laser power density is studied. Numerical simulation shows that the laser-tissue thermal interaction model has two stages

Based on argon laser of different wavelengths in visible light excited hemoglobin fluorescence spectra, it shows that there is one prominent fluorescence peak near 628 nm and the intensity increases with excitation light red shifting. The theoretical analysis indicates the hemoglobin fluorescence is mainly due to porphyrin fluorophores in it. In addition, it is found that the peak locations of 476.5 nm laser induced the fluorescence spectra hardly change with the sample concentration from 1% to 7%. The research indicated that the effects of laser are markedly different from that of normal light in the characteristics of low lever light-biotissue interaction.

Using the blood samples of animal, the in vitro effects of low power laser irradiation on erythrocyte rheology were investigated. After the deposited pig′s erythrocytes (the deformation of erythrocytes have already turned to worse) were irradiated with laser, the effects of laser irradiation on erythrocyte′s deformation were measured. When 650 nm laser was used for irradiation, the deformability of erythrocytes was improved obviously. The changing tendency is that, the erythrocyte′s deformation was enhanced with the increasing of irradiation power and then saturated around 4～5 mW. When the blood samples were irradiated by 650 nm and 632.8 nm lasers respectively with the same power (10 mW), the erythrocyte deformability in two cases were all obviously increased to the similar level. These phenomena can be explained by that, the hemoglobin in erythrocytes has the similar absorption to both lasers. Taking the mouse blood as the samples, the effects of laser irradiation on erthrocyte′s electrophoretic mobility was studied further. When irradiated by 632.8 nm laser, the electrophoretic mobility of erythrocytes was speeded also, reflecting the electric charges on the surface of erythrocytes were increased which will help to decrease the aggregation of erythrocytes. Under such low power irradiation (less than 20 mW), no morphological change was detected by the microscopy and no hemolysis was found also.

Thermal interaction of bio-tissues laser heated presents sorts of thermal effects such as coagulation, vaporization, carbonization. Both the thermal effects and thermal damage produce due to the continuously accumulation and diffusion of the laser energy in tissue. Based on the analysis of the mechanism of the thermal propagation and equilibrium, the relationship among temperature rise, thermal damage and exposure duration was deeply discussed. With increasing of the laser energy and thermal source diffuse to the ambient tissue, the distribution of temperature rise changes from a shape δ function to normal function, the higher temperature makes the thermal damage to some extent. It is theoretically proved temperature rise is one of the most important factors in laser surgery. Clinically, with the shortage of the setup to trace the actual temperature of the target tissue, one is only to adjust the laser output or the duration time in order to get better curative effect, which could tend to bring excessive thermal damage or insufficient irradiation.

Based on the photobiomodulation on wound healing of animal models, the stimulative effects of He-Ne laser irradiation on proliferation of human normal skin fibroblasts were used as the cell model to investigate the role of ketamine as an anesthetics in animal model experiments in this paper. The cell proliferation was measured using MTT-based colorimetric assay. The effects of 1.56 mW/cm2 He-Ne laser irradiation on human normal skin fibroblasts for 0, 10, 30, 100, 300 s, and on the cells preincubated with different concentrations of ketamine (0, 0.6, 1.2, 2.0 μg/mL) for 300 s were investigated, respectively. The results show that human normal skin fibroblast proliferation induced by He-Ne laser irradiation (468.7 mJ/cm2) was inhibited when the cells were preincubated with different concentrations of ketamine (0.6, 1.2, 2.0 μg/mL). These results suggest that anesthetics may affect photobiomodulation on wound healing.

Applying the antibody of CD34 stained the vascular endothelial cell of periodontal tissue and investigated the effects of He-Ne laser irradiation on the blood vessel remodeling (BVR) of orthodontic periodontal tissue in rabbit. 35 rabbits were divided into normal group and experimental group randomly. All of the tissue sections proceeded with CD34 immunohistochemical staining, measured the microvessel density (MVD) the microvessel area (MVA) of periodontal tissue by computer image analyzing system using SPSS software to proceed with statistic test. MVD and MVA received He-Ne laser irradiation were higher than those of the control side. The differences of MVD, MVA between the irradiated and control side in every experimental group were all significant (P<0.05, P<0.01), except for the 1st day group.

In order to get photodisruption threshold of porcine nasopharynx tissue in nasopharynged carcinoma optical biopsy, temperature distributions in the porcine nasopharynx tissue were measured under irradiation of argon ion laser at the wavelength of 488 nm and 514.5 nm, respectively. The dependence of the temperature distribution on the measuring position and irradiation power density, as well as wavelength was studied in detail. Experimental results show that the temperature distributions in the porcine nasopharynx tissue were significantly affected by measuring position and the power density, as well as wavelength of irradiation laser. The temperature in the porcine nasopharynx tissue is increased with the increasing of the power density of irradiation laser, and the maximal temperature can be higher than 41.5℃ when the power density reaches 1.85 W/cm2. The optical-thermal effect at the wavelength of 514.5 nm is more remarkable than that of 488 nm under the irradiation of same power density.

A study of using the laser speckle interference technique and spectroscope method to monitor the dynamic lymph flow. In present paper, laser speckle interference technique and spectroscope method were utilized to measure the lymph flow in the rat mesentery. The combination results obtained by these two methods demonstrated that the spectroscope method had promising to be used as a new approach in monitoring the lymph flow.

Digital photorefractor is an objective measuring system to measure the refractive error of eyes automatically by taking a photo of the pupil. The working principle of the system is described. The formation of pupil crescent image based on the light intensity is analyzed, which can give an outline of the intensity distribution of the pupil. The crescent image is then processed by computer according to the light distribution, which can increase the precision of the measuring system.

According the "black-box" theory, the study system of Turbid Media 180° Back Scattering Characteristic was designed. In this paper, two important Mueller matrixes-the back scattering of turbid media and reflection of beam splitter were deduced. So it was possible to study turbid media 1800 back scattered characteristic using matrix optics way.

Monte Carlo method is enhanced to simulate single-, two-photon excitation fluorescence microscopic imaging through turbid media Furthermore, a rapid modeling method, which is based on point spread function, is developed to study lateral resolution. Since simulation of scanning process in imaging is avoided, high efficiency is obtained. With this model, effects of numerical aperture (NA) on single- and two-photon microscopic imaging through turbid media are researched. Results show that higher NA brings lower lateral resolution but higher axial sectioning ability.

This paper describes the principle about the imaging system of the stereo endoscope. The system adopts two optica] channels stereo imaging technique to replicate human binocular vision. It employs time multiplexing art accomplished by images processor. By an active matrix liquid crystal screen and a circular polarized eyewear the synchronous separation of the left and right images will be shown. So this system can present strong stereo-inspection. This paper analyses and compares three methods of optical system. This paper also briefly introduces the application of this system in mini-invasive surgery (MIS) and measuring field.

In this paper, it is introduced the proximity focusing X-ray intensifier and Lixiscope system at home and abroad. Their quantification and feature are pointed out. The technological way and application prospect of improved Lixiscope were given.

Photon traditional Chinese medicine (PTCM), an inter-discipline of photonics and TCM, studies TCM, such as the diagnostics, therapeutics, indistinct disease theory, rehabilitation, health care and so forth, by using photonics. This report gives a brief review of some progress in the fields of basic theories, clinic basic research, diagnostics and clinic applications.

A full dynamic theoretical model was developed to simulate the dynamic evolution of coagulation in tissue, which accounted for the dynamics of the temperature and damage dependence of optical properties, thermal properties and blood perfusion rate. The simulations of the temperature distribution, coagulation depth during laser thermotherapy for full dynamic model are compared with the calculations from other models. The results showed that there are differences in temperature and thermal damage among these models. Therefore, mathematical modeling techniques that simulate laser coagulation may not provide reliable information unless they take into account these dynamic parameters.

A technique of monitoring the change of blood perfusion utilizing the principle of laser speckle technique combined with CCD imaging method was studied. A laser speckle measurement system of measuring the velocities of blood flow in rat's mesentery was designed in present paper. The parameter and precision of the system was testified by a model experiment. On this basis, the dynamic changes of the velocities of the blood flow in rat's mesentery under different temperatures were measured. Meanwhile, the diameter of blood vessels was measured with CCD camera. With these measurements, changes of blood perfusion by heat were studied. The results indicated that this system and method could be used to monitor the change of blood perfusion effectively. This work provides a new method to measure thermal induced change in blood perfusion of tissue.

Instead of cumbersome standard calibration chart method , this paper applied ray tracing method to analyze the formation of angioscope image distortion, developed a polynomial correction formula, and successfully realized the correction of angioscope image distortion.

Measurements of total reflectance and transmittance for porcine nasopharyngeal tissue using single integrating sphere technique were carried out under the irradiation of He Ne laser at the wavelength of 632 8 nm, which has the advantage over conventional double sphere techniques in that no corrections are required for sphere properties. Furthermore, with the measurement of collimated transmission for optically thin slabs, the optical properties of porcine nasopharyngeal tissue in vitro were indirectly obtained by applying inverse adding doubling theoretical model. The optical properties of porcine nasopharyngeal tissue are characterized by low absorption and high scatter, and the value for absorption coefficient and scattering coefficient are 0 96 cm -1 and 62 7 cm -1 , respectively. The scattered light is highly forward as demonstrated by the mean cosine of the scattering angle, and the optical penetration depth for porcine nasopharyngeal tissue is about 0 241 cm.

The physical mechanism of green laser inducing erythrocyte fluorescence spectra in vitro is analyzed by a model of non syntonic dipole in this paper. The theoretical investigation shows that while the erythrocyte from blood is radiated by a low lever frequency doubled Nd∶YAG laser with wavelength 532 nm, anisomerous C-C bonds or C-N bonds on membrane of the erythrocyte would absorb the energy by non resonance and be parted to produce lone pairs of electrons. The new fluorophores from the lone pairs of electrons under the laser excitation would emit fluorescence. It may supply some references to the explanation the mechanism of low level laser irradiating blood therapy in vivo.

The blood taken from a healthy human vein is irradiated by different wavelength lights at 502 nm, 530 nm and 632.8 nm. The fluorescent spectra are tested by the grating spectrograph. The result indicates that the fluorescent intensity of the blood induced by the light at 530 nm is the strongest. The fluorescence of the blood induced by the light at 502 nm is very weak. The emitting spectrum of the blood induced by the light of 632.8 nm appears in both side of 632.8 nm. This result shows that the processes of interaction between laser and blood may be different when wavelengths of the exciting lights are different. So the biological effects of the lights on the blood may be different.

The result shows that the wheat seedling has partly ability of excision repair, and the time of repair peak is about from four to six hours after the UV-B radiation. By excision repair pathway, the repair for the removal of damage induced by UV-B radiation from cellular DNA of the wheat can be influenced by He-Ne laser irradiation. The ability of excision repair of the wheat can be enhanced by He-Ne laser irradiation, and the excision effect of the He-Ne laser irradiation is obviously at the excision peak (at five hours) . The peak of DNA repair synthesis was from six to seven hours after treated by He-Ne laser and UV-B irradiation.

The killing experiment via photodynamic therapy (PDT) was carried on 30 Kunming mice inoculated with Louis lung cancer. The tumor suppressing rates and curves were observed between the experimental group and control group. Significant differences in the tumor growth curve (P<0.05), tumor mass and tumor volume existed between the two groups (P<0.01). The tumor suppressing rates of tumor volume and mass were 52.94% and 37.24%, respectively, in the experimental group. The results revealed selective injurious effect and growth suppressing effect of photodynamic therapy (PDT) on tumor cells, it is suggested that PDT can regulate the immune function for the mice inoculated with Louis lung cancer. Photodynamic therapy (PDT) will be a available therapy for malignant tumors.

Kinetics of thermally induced damage of rat liver at different constant temperature (55～95℃) were studied with continuous wave transillumination technique. It showed that thermal damage could be described by scattering coefficient. According to the relation of change in scattering coefficient and time at different temperature, the activation energy (E=135 2 (kJ/mol)) and entropy of activation  (Δ S=116 7 (J/K·mol)) were calculated. The thermal damage of rat liver was analyzed. This work provides a new method to measure thermal damage properties.

One dimensional analytical expression of the instantaneous temperature in biological tissue under laser irradiation without considering the bloodstream cooling is derived. The temperature in biological tissue increases in exponent with time and decreases in exponent with the distance from laser irradiating area.

Considering the heterogeneous thermal properties of living tissues, a multilayer heat transfer model for laser tissue thermal interaction is presented in this paper. A closed form analytical solution to the temperature transients within two tissue layers is obtained using the Laplace integral transform method. Heat transfer behaviors inside the tissues before evaporation were investigated. The critical time required to vaporize the surface tissue and the thermal damage depth are numerically predicted. Study shows that there is evident difference in temperature predictions between the uniform model and the heterogeneous one.

Using MTT to study the influence of He-Ne laser irradiation on proliferation of spleen cell and thymus cell with SP2/O marrow tumour mice. The result shows that the laser can enhance the activation of immune cell, as compared with the control group (P<0.01). This demonstrates that laser irradiating immune organ region has enhanced lymphocyte activation, promoted DNA duplication and increased immune function.

Using the fractal theory, this paper studies the ILLLIT's effects on the deformity of erythrocyte. The results of theoretical analysis indicate that ILLLIT surely can decrease the elastic modulus of protein, which is advantageous to improve the deformity of erythrocyte.

Considering the laser applications in biology and medicine as background, this paper presented a theoretical research on the hyperbolic heat conduction in laser irradiated tissue. A numerical model was established by combining the seven-flux model of light propagation with the two-dimensional hyperbolic heat conduction model in cylindrical coordinates. It showed that there exists a great discrepancy between the results obtained by treating the laser irradiation as volumetric absorption (i.e. taking laser scattering and absorption into consideration) and those obtained by treating the laser irradiation as the second boundary condition. The effects of the scattering and absorption coefficients of tissue on the hyperbolic heat conduction in laser irradiated tissue were discussed.

The paper reports the experimental results of CO2 laser and Er: YAG laser making holes in myocardium. It gives three experimental curves: h-t curve of CO2 laser's making hole in myocardium when power is 100 W, h-W curve of CO2 laser's making hole in myocardium when irradiating time is 0. 3 s, h-n curve of Er: YAG laser's making holes in myocardium when pulse energy is 500 mJ. It analyses the experimental results and provides a reference for clinical application of laser transmyocardial revascularization.

The broad bean (Vicia faba L.) seeds were irradiated by He-Ne laser and CO 2 laser, then both of MDA and AsA were tested in the stage of their seedlings. The results showed that He-Ne laser was better that CO 2 laser. The best dose of He-Ne laser was 5.43 mW·mm -2 . He-Ne laser pretreated seeds and 3.03 kJ·m -2 UV-B irradiated seedlings in the condition of PAR 70 μmol·m -2 ·s -1 . SOD, POD, CAT enzyme activity, SOD, POD, CAT isoenzymes were measured. The results showed that He-Ne laser could enhance SOD, POD, CAT enzyme activity, changed SOD, CAT isoenzyme bands. It was concluded that laser pretreatment could protect broad bean seedling from UV-B irradiation damage.

The microscopic fluorescence spectra and imaging of excised lung tissue sections were studied under a novel microspectrophotometer system using a He Cd laser light at 442 nm. Differences of the intrinsic autofluorescence distributions in different tissue layers, i.e., epithelium, mucosa and cartilage, were observed in normal and malignant lung tissues. The results show that the study of microscopic fluorescence on various tissue layers can be used to explore the origin of spectral differences between normal and abnormal lung tissues, which is very useful for the better understanding of the mechanism of the early cancer diagnosis using the laser induced autofluorescence technique.

Based on the principle of geometry optics, the confined equations of light propagation in contact laser scalpels are developed in this paper. By use of the Monte Carlo method, the emergent power distribution of the laser scalpels is simulated, the simulation results are consistent with that of the experimental measurements. Different design parameters that effect the emergent power distribution are discussed comprehensively. The simulation results will be benefit for the design of such scalpels and the determination of treatment schemes.

The diffuse reflectance and transmittance of human arteries and veins were studied with 632.8 nm of He-Ne laser. The measurements were performed with two standard integrating sphere systems. The absorption coefficient, scattering coefficient and the changes of total optical intensities I(x), forward scattering flux i(x), backward scattering flux j(x) as a function of thickness of human arteries and veins were evaluated and analyzed from the experimented data by Kubelka-Munk model. The results of measurement showed significant difference of diffuse reflectance and transmittance between arteries and veins at 632.8 nm wavelength of He-Ne laser. Furthermore, the absorption coefficient and the scattering coefficient of arteries were obviously bigger than that of veins at He-Ne laser wavelength. The changes of I(x), i(x) and j(x) as a function of thickness of human arteries and veins were also significant difference.

The quantitative relation between visual velocity and the moving velocity of laser speckle on retina is studied. By using laser speckle a prompt and precise method to examine the focal powers of abnormal eyes is given.

An experiment of Ar + laser coagulation of vas deferens which made on animals is reported. The experiment proved that Ar + laser coagulation technique can be apllied to clinic. It can reduce the postoperative complication and the patient′s moral pressure and pain.

The laser of Nd:YAP at 1341.4 nm transferred by fiber has not only coagulation and vaporization in tissue, but also weaker penetrability than that of the laser at 1064 nm, so it has high safety. By using the Nd:YAP laser with endoscope to treat 45 patients with gastroenteric hyper plasic diseases, the results showed that the laser of Nd:YAP at 1341.4 nm is a suitable laser for cavum organs by endoscope.

The introduction ofinsect-resistant δ-endotoxingene from Bacillus thuringiensis into Brassica napus was carried out by laser microbeampuncture. The acquisition of transgenic plants and the inheritance of transgene in T1generation were confirmed by PCR and PCR Southern blot hybridization. The bioassay oftransgenic plants showed that some of the plants exhibited tolerant to pest insects andinsect-resistance was maintained in the T1 generation. These results showed that theinsect-resistance gene was integrated into the genome of Brassica napus and was stablyinherited.

The effective trappingforce is defined and the effective force of a ring beam trap is calculated in the rayoptics regime. A comparison of the effective trapping forces is also given using solidbeam and ring beam. It is shown that the ring-beam gradient laser trap has a highereffective trapping force than the solid-beam laser trap and the stability of the ring-beamlaser trap is improved greatly too. Also the thermal damage of the ring-beam laser trap isreduced.

The resonant absorption effects and chaotic characters of the laser DNA molecule interaction are studied by quantum mechanics and nonlinear theory. The results may explain the effect of genetic mutagenesis of laser.

By the electron conformation theory, the influence of laser field on enzyme activity is studied. The results show that laser field is advantageous to activation of enzymes.

Effect of He Ne laser irradiation of the cervicales anteriores region and of acupoint irradiation on rabbits is studied. The nodi lymphatici cervicales anteriores were observed by optical microscopy and transmission electron microscopy. The serum IgG was measured with a simple immunodiffusion method. The results showed that the ultrastructures of many kinds of cells in the lymph nodes both region irradiated and acupoint irradiated were changed. The function of the cells appeared activized. The serum IgG of the acupoint irradiation groups was much more than the control group. It was suggested that He Ne laser enhancing of cellular and humoral immunities of the organism was on the basis of changes of the cell ultrastructures. In conclusion, the immunity of the entire organism was enhanced by the laser acupoint irradiation, but the region irradiation only improved the immuniactivities of the irradiated region.

This paper reports the establishment of a microvessels′ thrombotic model of Wistar rats and studies of the different doses of aspirin in the action on thrombosis using an argon laser. We found that the anti thrombotic action of aspirin was closely related to the doses which were used. However, the prothrombotic action of aspirin was observed in the ultra low dose.

In several ways of introduction of foreign gene into plants, laser microbeam puncture is a potential and available method for transformation of foreign genes directly into plant tissue. The purpose of this research is uptaking the laser microbeam puncture technique to introduce pBI121 plasmid DNA containing GUS gene into Lotus. The laser microbeam irradiation source was a third harmonic Nd∶YAG laser. Before irradiation, the cells of cotyledon must be pretreated in high osmotic buffer. Then cultured the punctured tissues on screening media containing kanamycin to select green transgenic plantlets. After the seedings were selected on screening medium (km 100 mg/l) for three generations, we got four transgenic plants. Two of them were tested by PCR with GUS special primer. The results were positive, and proved that the GUS gene had been introduced into Lotus. We have established a laser microbeam puncture transformation system of Lotus, and proved that this system was easy to operate and replicate with relative high transformation frequency, thus providing a new way for high plant genetic transformation.

The effect of a domestically manufactured excimer laser performed operation together with adujunctive balloon angioplasty in achieving revascularization and reduction of residual stenosis was assessed. 20 femoral arteries with thrombosis and occlusion from 10 dogs were subjected to angiography. At first an excimer laser angioplasty was done followed by the balloon angioplasty. The diameters and residual stenosis of revascularized vessels were measured. The result showed that 17 out of 20 vessels (85%) were revascularized. The typical diameter of the revascularized vessels after excimer laser treatment was 1.20±0.14 mm, while residual stenoses were 54%±5%. After an adjunctive balloon angioplasty the diameter and residual stenoses were 2.04±0.16 mm and 20%±7% respectively (P<0.05 and P<0.01). Complication in a form of vasoperforation occurred in 3/20 vessels (15%). It is concluded that China-manufactured excimer laser angioplasty is effective when used for revascularization. The reduction of narrowing and residual stenoses was enhanced after adjunction of the balloon angioplasty. It would be expected that this method can be employed in treating peripheral occlusive disease effectively and safely.

A new way for detecting medical X-ray image is presented. Instead of the traditional medical X-ray photo taken with a common medical X-ray machine, the method uses an image record plate emboarded in a novel detector to capture the image stimulated by a laser beam. The image is picked up and converted into digital singnal via an A/D converter, then the digital “image” can be displayed on CRT or stored in computer. Compared with the traditional method, the experimental result shows much higher resolution and lesser harm to human being's body. With the great practical value and bright application prospercts, this new method manifests a breaking through in the field of medical application by means of laser and computer technology.

In this paper, the dynamic equation of laser DNA intenaction turns into Duffing equation (DE), then the solution of DE is obtained by the analysis of primary resonance, superharmonic resonance and combination resonance of two frequency excitation. And therefore some incomprehensible phenomena in the laser breeding are successfully explained.

Thirty six guinea pigs underwent resection of the right facial nerve in the Patotidfossa. For twelve of them;the semiconductor laser with 500 mW output POwer was used toanaStomose the facial nerve. We observed the lantency of evoked compound muscle actionPOtentials (CMAP) and morphology of the repaired facial nerve preoperatively in 4, 6 and 8 weeks postoperatively and compared with the other animalSI facial nerves which wereanaStomosed with conventional monofilament and multifilarnent suture. We found the laser-using method of anastomasis was better than that of anastomasis used with conventional multifilament but had neither beneficial nor detrimental effects than that of monofilament. It is concluded that using semiconductor laser to repair facial nerve may be efficient.

It is reported for the first times that prostate samples of rabbits are irradiated by a Xecl excimer laser (308nm).The ablation effects of the prostates of the rabbits are observed with different laser pulse repetition rates and two lasing media. The damase threshold of 400 mJ/ cm2 is measured. It is shown that the excimer laser has the characteristics of good ablation effect, light damage for surrounding tissues and easy control,thus presenting a practical clinical value.

Seventy patients with 316 tumors of urinary bladder have been treated by photodynamic therapy (PDT) with a gold vapour laser. All cases were histopathologically diagnosed as transitional cell carcinoma. The power output from the tip of an optic fibre was 2.0～2.5 W and the power density used was 70.8～509.6 mW/cm2. The pulse duration was 20～50 μs, the pulse energy was 0.5 mJ per pulse and the repetition rate was of 6000～9000 Hz. Both the tumors and whole bladder were irradiated. Hematoporphyrin derivative (HpD, Yanzhou Biochemical Pharmaceutics, China was given IV in a dose of 5 mg/kg in 250 ml of 5% glucose, 48 hours prior to irradiation. The results of a follow-up of 4～46 months are as follows: cured, 54 case (77.14%); good effect, 12 (17.14%); and improved, 4(5.7%). Tumor regrowth occurred only in 8 cases (11.43%) within 3～9 months after PDT. The results suggest an increase of cured ratio and a decrease of regrowth ratio and the reoccurrence ratio of tumors has compared with results obtained by other treatment modalities.

This paper presents experimental studies in which the drying corn seeds are irradiatedby He-Ne laser at power densities of 2.8 mW/mm2,3.8 mW/mm2 and 5.4 mW/mm2, respectively, and the corresponding irradiating times last 5 s, 50 s and 500 s. As a result, the POD and CAT activities of corn seedling are enhenced while their AsAPOD activity is reduced and their GSH contents are increased. Consequently, the improvement of the active oxygen metabolism for plants the seeds of which have been irradiated can be expected.

Influence of He-Ne laser analgesia on physiological function of horses was estimated by analysing the parameters such as cardiac function, blood gas and electroencephalogram. The results provided new basis for choosing analgesic method in veterinary practice and studying the mechanism of He-Ne laser analgesia.

Request for laser characteristics of keratoplastic surgery is described. It is reported that RK and PRK experimental studies of animals eyes using an ArF excimer laser manufactured on our own are performed.

This experiment studies the light absorption laws of the blood componentS between 240 to 800 nm. The results show: 1) The absorbance and transmittance laws resemble each other in blood of Group A, B, AB and O. 2) Between 600 to 800 nm, absorbances of the whole blood, erythrocyte, leukocyte, plasma and serum are less than 5 percent, while the transmittances of them are more than 95 percent. 3) To erythrocyte and lymphocyte, typical absorption peaks appear at (416.57±1.90) nm, (542.71±1.80) nm, (578.57±1.81) nm.

The research results about fish breed using laser irradiation was reported. A new breed, two tails brocaded carp-China colour carp was cultivated successfully. New it aready inherite to third generation, but its form was not change.

The effect of coloured egg by race, dosage and temperatur on the survival rate was studied. The results showed the laser-induced-colored egg rate reaches 55%. This experiment showed that the newly hatched larvae were all female from the eggs of parthenogensis of silkworm by laser Irradiation. Compared with their parents, the offsprings exhited sluggish larva grow-up, the cocoon quality improved and the deformed silkworms were faw in the rearing tests.

In order to prove the feasibility, advantages and welding mechanism of vascular anastomosis using low power laser, we performed a comparative experiment in 125 rats with the carotid arteries and veins anastomosed by CO2 lasers and hand suture.

After irradiating by CO2 laser (power density : 825mW/cm2for 10,13,15 seconds respectively), the seed vigor are greatly promote'd.

High yield strains in laser breeding of S. rimosus were obtained by irradiation with He-Ne laser or copper vapor laser. It increased yield by about 6. 79% higher than that of the controlled ones. The highest unit of fermentation arrived at best level. It was already applied in China.

Fluorescence spectrum of transplanted tumour (mammary cancer), normal skin and gastric mucosa injected with AlSPc plus excited by dye laser (λ=607 nm) were studied in 18 mice. The main fluorescence peak of the tumour tissues spectra are located at about 681.9 nm, whereas this peak of normal skin are located around 682.7 nm, and the grastric muoosa are at 682.2 nm. The fluorescence intensity of the tumour than normal akin is 7.5:1 and the fluorescence intensity of the tumour than normal grastric mucosa. It has demonstrated selective localization and retention of AlSPc in cancerous tissues and SlSPc was less cytotoxic to cells. It may become a new potential photosensitizer in PDT of cancers.

Based on experimental of irradiation of 60 rabbit's brain with a CO2 laser, we studied the ultrapathologicai change and the reversity of the damaged tissue. The author thought that the damaged area of brain tissues irradiated by CO2 laser could be classified into 4 zones : charring zone, coagulation zone, edema zone and periedema zone. The total width is about 380 μm and the irreversible area of damaged tissue is about 300 μm.

This research shows that He-Ne laser plus anthralin has a distinct effect on proliferating the number of blood vessels and folliclis of rabbit's skin, and the growth of hair was very fast. This result has provided the basis for the clinical practice.

Using Nd:YAG laser and optical fiber with a metal tip, 8 patients' 10 totally occluded peripheral arteries have been successfully channelized without hemorrhage and perforation occurred. The laser energy was from 360 J to 2808 J, and the length of channelized segments was from 6 cm to 45 cm. 7 patients had follow-up examination with Doppler velocimetry at one year. All of them didn' t have recurrence of symptoms.

laser acupuncture; He-Gu acupoint

A three-layered model of Monte Carlo simulation for photon flux in skin was presented. From the results of simulation we know that by varying the distance between the inner edge of the ring detector and the beam, we can measured the blood flow at different depths. The dependence of detected photon number on the frequency shift showed an exponetial decrease. By varying the blood volume fraction (Vb) , we investigated the effect of multiple scattering on the total frequency shift and the mean frequency shift. When Vb0.01, it reflected the root-mean-square velocity.

Investigation of Chinchilla rabbits' corneal losions induced by 308 nm excimer laser was presented. The damage mechanism was the same as photo-chemical and there were two phases of reaction of immediate damage and delayed ones. By statistical analysis, the immediately corneal injury threshold (ED50) of 0.485 J/cm2 was obtained and its 90% confidence limit was 0.349～0.608 J/cm2. The delayed reaction appeared 6～18 hours after the irradiation.

Light propagation in two-layered skin mode was simulated with Monte Carlo calculation using two diferent phase functions to give the photon-RBC (red blood cell) scattering angles for comparision. Results include:the intensity distribution of detected photons, the dependence of photon number on frequency shift, the dependence of total frequency shift and mean frequency shift on RBC concentration. The results show that the linear dependence of total frequency shift on RBC concentration is valid only when the concentration is low. At low concentration the first moment F and the first weighted moment (Δf)s of the spectral power density of intensity fluctuation reflect RBC's mean velocity while at high concentration they reflect RMS (root-mean square) velocity.

A XeCl excimer laser at 308 nm was used to irradiate rabbit's dog's aorta and different organs. Fluorescence spectra indicated a broad-continuum emission from 300 to 700 nm with the peak fluorescence at wavelengths of 380 and 450 nm. The ratio of peak fluorescence intensity is I380/I450=1.05±0.07 for nomal artery, I380/I450=1.32±0.10 for atheromas plagues.

For increasing the production of Getamicins, a He-Ne laser was used to mutate the protoplast of Micromonospora echinospora. The strain a was obtained through experiments which could produce more Getamicins than the original one.

Using nitrogen laser at the wavelength of 337.1 nm as an excitation source, the fluorescence lifetimes of normal intimae, atherosclerotic plaques and thrombo-emboli were measured. Results indicated that time-resolved fluorescence can be utilized for diagnosis of the lesions in the artery vessels.

Different wavelength lasers (308 nm, 193 nm and 2.94 μm) were used to irradiate cornea. Morphological changes of epithelial and endothelial cells were observed by quantitative image analysis. It was found that epithelial cells of cornea irradiated by 308 nm excimer laser have apparent changes in nuclear area and morphology. The epithelial cells regenerated after 193 nm laser irradiation have no obvious change. After 2.94 μm laser irradiation, no change in nuclear morphology and area was observed. But it was harmful to endothelial cells, if energy density or ablating depth was excessive.

Nd:TAG laser of 3mJ, 10ns, and 15um was used to make 30 points of anterior capsulotomy arranged in a circle on the lenses of 14 chinchilla rabits (28 eyes). Tonometrics, anterior segment fluorescein angiographies, aqueous protein centents, and ERG and Mstologica] examinations were done at intervals before and after the operation. The mechanism of IOP elevation after operation was discussed.

The fluorescence quantum yield of new photosensitizer-aluminum sulfonated phthalosyanine (AISPC) was measured as 0.53, 21 times higher than that of HPD. which shows that AISPC has potential usage in tumor detection. In vivo measurement on mouse by using He-Ne laser induced fluorescence showed that, AISFC can selectively retain in 8-180 tare cm a, and the maximum tumor; normal tissue ratio achieved 24-36 h after AISPC injection is about 2.5:1.

He-Ne laser (35mW) irradiation on Syrian hamster embryo flbroblast cells in Titro cultures directly induced malignant transformation. He-Ne laser transformed cells elicited fibrosarcomas ia BALB/c-nu/nu mice and have aneuploid karyotypes.

The study of irradiation in streptomyces aureof aciens with copper yapor lasar is reported. High yield strain with laser breeding of S. aureofaeiens is also obtained, which increases the unit of fermentation by about 12% than that of control group.

A comparative experimental study results are reported in this paper in 125 wisiar rats to small artery and carotid common veins anastomoses between low power CO2 laser welding and traditional hand suture.

Laser-mutagenesis of -earotene producer Dunaliella salina were investigated. Tie algal survival rate is above 90%. After mutagenesis three mutants were screened, in which the growth rate and length of alga were increased by 20% and 7.5% respectively aa compared with the original D. salina. The productivity of -carotene was 0.48mg-100 ml-1day-1, and waa increased by 19%.

In this paper, we introduce an advanced method of myocardium punching by laser beam. The experimental results were given on live aninalg in acute phase under the room temperature conditions by 100 watt quasi-CW CO2 laser. The experimental results demonstrate that laser punching in myocardium can rebuild myocardial microciroulation.

Some of experimental results on 308nm XeCl laser ablation of polymers and biological tissue and on cutting of eyeball cornea are presented. Cemparison is also given of the results on the ablation of biological tissues by nanosecond (NS) and picosecond (ps) YAG laser at 1.06 μm and at 0.53 μm.

The carbon dioxide (CO2) laser of 3W output power for repairing forty-four tibial nerves of rabbit with seel scalpel blades, and then the epinenrial repairs were completed using either standard mierosuture or CO2 laser-welding technique. The regenerative nerve was investigated by nerve conductive velocity and optical and electron microscopes after nine weeks postoperatively.

The experimental horses were irradiated by a He-Ne laser beam on the palpebra tertja at a dosage of 3.5810J/cm3 per day lor 12 consecutive days. After irradiation, the content of IgG,IgM and IgA in serum were all increased significantly;the number of T-cell and B-cell in circulatory blood was increased significantly; the index of stimulation and counts perminuted in lymphocyte transformation test, and the activity of total complements in the serum increased significantly after irradiation.

Cytotoxic effect of the new photosensitizer hypocerllin plus light exposure on PTK2 and heLa cells in vitro was studied by means of He-Ne laser microirradiation. The absorption spectrum and HPLC of hypocrellin were also investigated. It showed that hypocrellin might be an effective photosensitizer in photodynamic reaction.

Myocardial revascularrization by laser is a kind of operation which uses laser beam to converge on the surface of myocardium and punch from epicardium to endocardium. The blood in heart can directly make nutrition for myocardium. It is not neeessery to incise heart and put into bridging operation. Experimental results are reported about punching minute holes in myocardium of animals (i. e pig, dog, or sheep) by CO2 laser to improve the myocardial microcirculation.

The change of normal aorta wall irradiated by XeCl excimer laser were observed at various laser pulse energies and pulse repetition rates with different medium at the aortasurface.

Human osrvix Hela cells were synchronized, collected and seeded into Rose chambers for experiment. Cells at G1, S and G2 stages were then treated in the medium with hematoporphyrin (HPD) and irradiated by a laser mierobeam at 632.8nm. It was found that in case of the occurrence of primary and significant visible damage, cells at S stage showed the earliest, G2 stage the next, and G1 stage the latest. Variance analysis demonstrated that the variations are statistically significant.

Chromosome samples were prepared from dividing cells of root topa of broad bean, maize, wheat, and barley, etc. by means of aquash method. Miero-disseetion of chromosome was performed on the microscopic stage using argon laser microirradiation (514.5 nm). The chromosomes could be dissected into 12,6-9,6 and 4-6 chromosomal fractions respectively while the suitable laser power densities were applied. The establishment of laser micro-dissection of chromosome in plants provides the possibillity of the application of laser microbeam irradiation in chromosome engineering, assignment of genes, and DNA micro-cloning from chromosomal fragment in crons.

The changes of pain threshold and two neuropetides, substance P (SP) and methionine-enkephalin (ENK), were observed after He-Ne laser irradiating at acupoint(LIA) of rats. The pain threshold was very significantly higher after LIA than before (P<0.001). The SP-LI was obviously enhanced (P<0.001), whereas the ENK-LI markedly diminished (P<0.001) in the rats of laser group as compared with those of control group.

Canine femurs were ablated with an Er:YAG laser (2.94μm) with a pulseduration of 250μs. The bone ablation characteristics at four difierent pulse repetition rates (l-4Hz), were studied. The ablation depth versus energy density per pulse seems to follow an exponential function for large range of energy density. The increase of ablation ratio versus energy density at 1Hz was the highest, 2Hz the second, when the energy density levels were less than about 100 J/cm.

The genetic effect of two stocks of D. melanogaster, C. S., Base, were studied with irradiation from CO2 laser. Experimental result shows that when the radiation dosage of CO2 laser amounted to 69.5 J/cm3, the genetic effects of recessive lethal mutation is distinctlyhigher than those of the contrast.

Using a new diagnostic system composed of an argon laser, optical multichannel analyzer and fiber optics, the authors have detected the autofluoroscence spectra with porphyrin specific peaks from all of twenty three eases of oral cancers and seven out of eight premalignant legions as well as from some benign tissues. The cases of false positive and negative diagnosis are described and the identification for them are discussed.

QHS and SRFC were applied to observe the effects of He-Ne laser irradiation on AFC in mice. The results show the spleen region in mice irradiated by He-Ne laser at three-different power levels can increase antibody forming cell activities. The laser irradiated groupwas compared with that of the noemal control group, the difference waa highly significant (P <0.01). The resluts show that laser may have some immunoreguation action.

Withered grass bacilli were irradiated respectively by nine output spectral lines (454.5-514.5nm) of Ar+ laser with an irradiation dosage of 3×10-2J/cm2. The frequency dependence of Ar+ laser action on withered grass bacilli was obtained. The experimental results showed that along with the increase of Ar+ laser wavelength (from blue light region to green light region), the promoting reproductive action of Ar+ laser on the withered grass bacilli gradually decreases and finally the restraint reproductive action was produced.

The effect of laser irradiation on rabbit's sperm in-vitro fertilization were studied by using SPA(Sperm Penetration Assay) method and it has been found that laser may promote the formation of male pronueleus after fertilization.

Two kinds of mutants in egg color of laser-treated silkworms are analysed by esterase isoeuzymes zymogram and cross test, the results show that the new recessive mutations Zeω or Zepe gene is allelomorph with white-egg 2 (ω-2) and it is non-allelomorph with red-egg (re), which has been known to be recessive epistasis.