As an imaging technique, optical coherence tomography (OCT) is widely adopted in the field of biomedicine. The clear structure of retina can be obtained by OCT, which is important for the diagnosis of retinopathy. In this paper, reviewed are some excellent methods to retina OCT B-scan image segmentation. The OCT segmentation approaches are classified into two distinct groups according to the output-style of segmentation algorithm, which are layer-edge method and layer-self method. The differences among methods are analyzed to provide references to retinal diagnosis and algorithm researches.

The latest research progresses on the fabrication methods of microlens arrays are reviewed, and the fabrication methods are compared and analyzed in detail by categorizing them into direct and indirect ones. The research progresses of light field imaging based on microlens are reviewed, and it is indicated that the research focus is still on the new design of light field camera and corresponding model algorithms for improving the imaging resolution.

The catastrophic optical mirror damage has a significantly negative effect on the maximum output power and reliability of the high-power diode laser, which is the main mechanism of its sudden failure. How to overcome the catastrophic optical mirror damage of the cavity surface to obtain the high-performance diode lasers has become an important research topic at home and abroad. Firstly, the research process of catastrophic optical mirror damage is briefly introduced in this paper. Then the mechanisms and the thermal kinetics of the catastrophic optical mirror damage are discussed. Finally, various surface passivation technologies are summarized one by one from the perspectives of technical principles, methods, advantages and disadvantages and the improved methods, research progress and application status.

The bound state in the continuum (BIC) found in artificial microstructures such as photonic crystals is located above the light cone but not couples with the background leakage modes, and therefore it has an infinite Q factor, making lasers working at BICs or quasi-BICs have the advantage of low threshold. And low-contrast grating is often used in the mode modulation and out coupling of low-cost lasers. For the simplified three-layer slab structure of the lasers, it is proposed to induce a quasi-BIC with the Q factor of 9.2×105 by etching the low-contrast grating (LCG) in the top cladding layer. Besides, it is found the thickness of active layer is more sensitive to quasi-BIC lasers than the depth of etched LCG, and the Q factor can be maximized periodically up to 9.66×106 with the increase of the thickness of bottom cladding layer. The results are instructive to the design of grating-based low threshold electrically injected surface-emitting lasers.

The optical sensor based on dispersion-turning-point long period fiber grating (DTP-LPFG) modified by graphene oxide (GO) was investigated, and its spectral characteristics and sensitivity to external refractive index (RI) were analyzed. The DTP-LPFG with a period of about 136μm was fabricated by using a quasi-continuous KrF laser in a hydrogen loaded single-mode fiber. GO was fixed on the grating surface by hydrogen bonding to form a GO functionalized DTP-LPFG sensor. The experimental results show that there are a blue-shift and a red-shift of the resonant bands at the lower and higher wavelengths, respectively, and the wavelength separation between the dual peaks increases with the deposition of GO on the surface of the DTP-LPFG. The sensitivity of the resonance bimodal spacing variation of the GO coated DTP-LPFG sensor is about 831.89nm/RIU in the RI range of 1.33~1.38, which is 1.05 times higher than that of the uncoated one.

Based on the principle of surface plasmon resonance (SPR), a dual-channel optical fiber surface plasmon resonance sensor based on composite membrane was designed. The simulation software of FDTD Solutions was used to simulate and analyze the electric field transmission mode of the sensor, the performance of the single-layer metal Ag film and Ag-ITO composite membrane was compared, and the structure of single channel and double channel was analyzed comparatively. The results show that the sensitivity and quality factors of the dual-channel structure with Ag-ITO and Au-TiO2 composite membrane are obviously better than that of the traditional single-layer metal film and single-channel structure. The designed sensor can not only solve the crosstalk problem of resonance wavelength by the high differentiation of resonance drift range of the two sensor channels, but also one of the sensor channels in the dual-channel structure can be used as a reference channel to provide self-compensation capability for the sensor.

Organic-inorganic hybrid perovskites have been proven to be a kind of excellent light-absorbing materials for high-efficiency photovoltaic applications. At present, the ways to improve the efficiency of solar cells mainly focus on optimizing the grain morphology and interface modification of perovskite films. In this paper, a simple surface treatment technology is reported to increase the photoelectric conversion efficiency of perovskite solar cells from 19.46% to 21.56%. The improvement in efficiency is the result of increasing the open circuit voltage from 1.04 to 1.11V without sacrificing short circuit current and filling factor. The method of increasing the open-circuit voltage provides a new way to further improve the reliability of perovskite solar cells.

A terahertz ultra-narrow band absorber based on metal ring structure is proposed. The unit cell of the absorber adopts typical metal-dielectric-metal structure, the top metal pattern consists of closed metal ring and four-split metal ring, and the bottom layer is continuous metal plate. The narrow band absorption principle of the absorber and the surface current distribution of the absorber structure at the absorption peak frequency were studied. The research shows that the absorber possesses a narrow absorption peak at 1.7682THz, the absorption is 99.8%, the full width at half maximum relative to the resonance frequency is 0.51%, and it is polarization insensitive to the polarization of x and y incident waves. The absorber characterized by simple structure and easy processing has potential application value in bio-sensing, narrow band thermal radiation and photoelectric detection.

Based on the theory of multimode interference and self-imaging effect, a high sensitivity multimode interference-heterocoreless (SNS) fiber optic refractive index sensor was designed. The multimode interference is generated by the core mismatch between the cladding excited high order mode and the fundamental mode coupling in the coreless fiber to realize the sensing measurement of refractive index. The beam propagation method (BPM) was used to simulate the transmission spectrum of the sensor under different refractive index conditions, and the influence of the length of the coreless fiber and the refractive index of the external environment on the performance of the sensor was discussed. The transmission spectra of sucrose solution with different concentrations were measured by the preparation of a coreless fiber SNS structure sensor, and the experimental results were consistent with the numerical simulation results. The results show that, in the range of refractive index of 1.330~1.419, the wavelength sensitivity of transmission valley reaches 189nm/RIU, and its transmittance sensitivity reaches -40%/RIU.

Dynamic windowing readout and image transposition are significant functions of large format focal plane imaging detector, and also it is necessary to realize low power consumption. Based on the standard digital circuit design process, a new counter based on Gray code was designed to access the row and column address. The RTL simulation results show that the proposed design can achieve the functions of dynamic windowing readout and dynamic image transposition. A TSMC 90-nm process with 3.3V supply voltage was used to implement a 1024×1024 design, and it concluded that the power consumption of the addressing counter is only 19.56μW and the overall design power is only 58.75μW. This design is suitable for the design of readout circuit of large format focal plane system.

Proposed is an enhanced fiber expander with active coexistence (ACEX-RE), composed of a pair of integrated hybrid optical amplifiers (EDFA and SOA) and coexistence element (CEX) modules. The modules are installed on the central exchange (CO) together with the OLT system as the intensifier of downstream/upstream optical signals and the preamplifier respectively. Under the downstream and upstream wavelengths of 1577 and 1270nm, the performance of the XGS-PON system consisted of GPON and TWDM-PON was tested. The results show that the proposed ACEX-RE can support multi-rate XGS-PON with a maximum operating distance of 35km, a beam splitting ratio of 1∶128, and a link loss of up to 44dB.

Three approaches were performed to achieve the charge balance in normal structure QLEDs so as to improve their external quantum efficiency: by inserting an ultra-thin PMMA electronic barrier layer between the lighting emitting layer and electron transport layer of QLED with the structure of ITO/HIL/HTL/QD/ETL/EIL/metal cathode;by optimizing the hole injection layer in the hole side to improve the probability of hole injection and transport; replacing the long chain ligands of quantum dots with short chain ones to help the charge injection and transport into the emitting layer, so as to improve the device performance. Another benefit of the ligand exchange is the improved solubility of quantum dots in orthogonal solvents of charge transport layers, which is essential for full-solution processed QLEDs.

A high-reliability optical fiber probe was designed and developed for the void fraction measurement of the oil-gas-water three-phase flow in oil and gas wells, for which, a conical sapphire structure was used as the sensitive tip of the probe. The gold-based solder was exploited in order to seal the sensitive tip and the transition tube, as well as the transition tube and the protective tube. Experiments were carried out to test the reliability and void fraction, and the results show that the designed optical fiber probe is able to withstand high temperature (150℃) and high pressure (100MPa) with a high reliability. In the pipe string, the void fraction of the three-phase slug flow is 46%. The research results not only verify the feasibility of using optical fiber probes to measure void fraction of oil and gas wells, but also provide theoretical basis and practical guidance for the follow-up engineering application.

Taking graphene as the sensitive material of the pressure sensor, Si as the base material, PN as the graphene protection material and Wheatstone bridge as the force-electric transformation measurement circuit, a new structure of silicon-based graphene pressure sensor was constructed. Based on the established theoretical model of the sensor with the foam experimental method, the relationship between the pressure of the sensor and the central change displacement was analyzed. And by combining with the ANSYS software static nonlinear analysis unit, the value analysis and finite element simulation were carried out to analyze the characteristics of deflection deformation of the graphene film. The results show that the theoretical analysis results of graphene film pressure and deflection deformation are consistent with the simulation ones.

Mask copying process is often used in the LED industry since it can be produced in large quantities with low cost. Influenced by the flatness of the glass substrate, the optical diffraction effect will cause the distortion of the micron-level graphics in the mask copying process. Aiming at eliminating the graphic distortion in the mask copying process, a method was proposed by adjusting the lithography process and resist thickness. The experiment realized the mask copying process for circular graph with the size of 4μm. The experimental result shows that this method can improve the process of mask copying for micron-level graphics and reduce the cost significantly.

Multi-crystalline silicon (mc-Si) solar cells with passivated emitter and rear cell (PERC) structure were successfully fabricated on an industrial production line, and the effects of PERC structure on the power conversion performance of the solar cells were studied. The results indicate that, the PERC mc-Si solar cells exhibit an enhanced short-circuit current and open-circuit voltage, resulting in high power conversion efficiency of up to 20.14%. The enhanced optoelectronic conversion can be attributed to the reduced parasitic absorption loss of long wavelength photons and reduced recombination of charge carriers on the rear surface of PERC mc-Si solar cells. The PERC structure can improve the conversion efficiency of mc-Si solar cells, and can be compatible with traditional process, thus it can be regarded as an optimal cell structure.

In this work, a triangular silicon dimer nano-antenna structure was proposed, which can improve the fluorescence emission efficiency of the dipole source in the excitation and emission process at the same time, and realize the enhancement of far-field directional emission. The effects of the combination of the dimer, the size of the triangles right-angle side, and the spacing of the dimer on the enhancement effect of fluorescence emission were studied by using the finite difference time domain method, and the structural parameters were optimized. Finally the effect of the structure on the fluorescence excitation process was studied. The results show that the triangular silicon dimer nano-antenna structure with the right-angle side length of 300nm and the dimer spacing of 0nm are the optimal parameters of the nano-antenna. Compared with the bare light source, the fluorescence emission intensity of silicon dimer nano-antenna is increased by 7 times, and the far-field directional emission is realized. Moreover, under the excitation of 405nm wavelength light, fluorescence excitation enhancement can be achieved.

With the characteristics of high sensitivity and small volume, photon counting radar represents the future development trend of long-range detection radar. But photon counting radar in the detection will produce range walk error, thus affecting the ranging accuracy of the system. In this paper, the relationship between the range walk error and the detectors timing jitter is theoretically analyzed and experimentally verified. First, based on the lidar equation, timing jitter of single-photon detector and probabilistic statistical properties of photon counting detection, a mathematical model of the echo signal and detector timing jitter was established. Then the model was used to further derive the detectors timing jitter and range walk error. Computational analysis and simulation experiments show that the range walk error of the system is positively correlated with the timing jitter of the detector. Finally, experiments were conducted using single-photon detectors with different timing jitter, and the results show that when the standard deviation of the detector time jitter is 15, 350 and 1152ps, the walk error is 0.88, 2.55 and 12.56cm, respectively.

Fiber optic gyro curve mode detection system is a method for measuring the pavement curve mode. By combining the detection principle of fiber optic gyro and the pavement evenness index, a method for obtaining pavement evenness is proposed. The experimental analysis and application results show that the probability distribution and standard deviation of the angular velocity collected by FOG in the process of curve measurement have a strong relevance with the pavement evenness. By extracting the bridge curve height standard deviation detected by FOG, the pavement evenness coefficient can be obtained. This method can reflect the macro evenness of the pavement surface and the driving comfort transferred from the pavement to the vehicle. It also can realize the simultaneous measurement of the bridge curve and evenness, which presents the advantages of convenient, efficient and accurate, and great application and promotion value.

For the problems of tracking drift or loss in the tracking algorithms of correlation filter, which is caused by fast motion, occlusion and appearance variation of objects, an object tracking algorithm with kernel cross-correlator based on temporal consistent constraint is proposed. A kernel cross-correlator vector, which is more robust to image noise and clutters, is introduced to predict affine transformation of object more precisely. Meanwhile, to solve the problem of tracking drift caused by temporal degradation of kernel cross-correlator, temporal consistent constraint is introduced during learning process. Finally, MGC(major gray component) anti-projection is utilized to improve the ability of the tracker to deal with occlusion of object. The proposed algorithm is compared with provided benchmark algorithms and other more advanced correlation filter based algorithms on public OTB100 standard object tracking datasets. The tracking speed of proposed algorithm precision reaches 41f/s, and compared with fDSST and SAMF algorithm, its tracking precision is increased by 15.6% and 6.4%, and the success rate is increased by 33.3% and 6.1% , respectively. The experimental results demonstrate that the proposed algorithm is able to track objects precisely under the condition of fast motion, occlusion and appearance variation.

The output performance of semiconductor laser directly determines the measurement accuracy and long-term operation stability of the optical fiber current transformer. Thus in order to improve its measurement accuracy and stability, a high-precision digital driver circuit of semiconductor laser was designed. STM32 microcontroller was used as the main control chip, high-precision current source chip ADN8810 was used to control the driving current precisely. And integrated temperature control chip MAX1978 was adopted to control the working current of semiconductor coolers to realize the precise temperature control. The experimental results prove that the output current stability is 0.028% and the stability of temperature control is 0.18%. The optical power stability reaches 0.06%, and the wavelength stability reaches 0.05pm. The design can meet the output performance requirements of light source of the optical fiber current transformer.

Aiming at the congenital shortcomings of traditional multi-resistance intelligent algorithms to deal with the problems of accurate modeling of heterogeneous photovoltaic power forecasting, such as the lines multi-impedance parameter constraints, lower fluctuations, and line loss analysis easily falling into local extremes, a prediction model for short-to-medium-term photovoltaic power generation is proposed based on improved depth deterministic policy gradient (DDPG). Firstly, by introducing multi-agent mechanism and considering the parameters involved in the power generation system as independent active agents, constructed is a global optimal collaborative control system oriented to power generation process parameter information sharing with social attributes. Then, the battery energy storage power can be adjusted independently and accurately and the power grid output power can be automatically and optimally predicted by using the improved DDPG algorithm. Finally, based on the Tensorflow open source framework, the model efficiency was simulated under the Gym torcs environment, and a model heterogeneous photovoltaic power generation network was used as the performance evaluation carrier to verify the rationality the model.

Based on analyzing the noise properties of CCD camera, a new method was proposed for testing its electronic gain. Applying arbitrary scene, the linear relationship between the image signal SDN and the image noise σDN was deduced with an improved algorithm, and the electronic gain of the CCD camera was calculated. Different from the traditional methods which apply integrating sphere or uniform light source required by EMVA 1288 standard, the new method presents the characteristics of simple operation and high economy. Comparison experiments were performed between the traditional and the proposed methods, and the results indicate that, the new method can test the electronic gain of CCD cameras precisely and effectively with a high repeatability.

In order to mitigate the problem of strong nonlinear effect in the long-distance unrepeatered transmission system, the performance of phase conjugated signals was studied. The performance difference between single polarization and phase conjugated system was analyzed by simulations. Simulation results show that the dispersion pre-compensation of the phase conjugate signals is different from that of the relay transmission system. Compared with the single polarization signal, when the transmission distance is 330km and the backward pump is set to be 0.8W, the BER performance of the conjugated signal can be improved by more than 2dB for 32-GBaud QPSK when the forward pump is 0.4, 0.6 and 0.8W, respectively. Meanwhile, the transmission distance of the phase conjugated signal is increased by about 10%.

Traditional human blood glucose testing methods are invasive and have certain limitations. In this paper, a new technique is proposed by combining energy conservation method and spectroscopy to realize non-invasive, real-time and accurate detection of human blood glucose. Firstly, a body sign data collection device was designed to collect blood glucose-related data in real time and upload it to the upper computer. Then the data were analyzed and evaluated with such three different machine learning algorithms as multiple linear regressions, k-nearest neighbor regression and support vector regression, thus the optimal algorithm for non-invasive blood glucose detection could be confirmed by comparisons. Experimental results show that, the proposed technique for noninvasive blood glucose detection realizes high feasibility, accuracy and robustness, the measurement accuracy based on the support vector regression algorithm is the best, and the correlation coefficient reached as high as 0.862.

The vein images collected by using the principle of vein recognition are usually blurred and difficult to distinguish. The traditional CLAHE algorithm can improve the contrast of vein images, but will lose some details of the image. Therefore, a vein enhancement algorithm based on CLAHE and multi-scale detail fusion is proposed. Firstly, the ROI of the vein image is extracted, and the CLAHE algorithm is used to enhance the contrast between the vein and the back of the hand. Then, the multi-scale detail fusion algorithm is used to obtain the detailed image of the vein image, and then the high-frequency noise is filtered out in the detail layer through the average filter. Finally, the images obtained by the two methods are weighted and superimposed to obtain vein images with enhanced details. Experimental results show that this method not only improves the contrast of the vein images, but also retains the details of the original images.

In the practical application of camera pose estimation algorithm, affected by the matching error, the reference points often contain outliers. In view of the weak ability of existing algorithms to resist the outliers, a binary weighted algorithm based on orthogonal iteration is proposed. Based on the orthogonal iterative algorithm, a weighted system with two thresholds is introduced to measure the reliability of the reference point. The maximum value of the quartile of the reprojection error is selected as one of the thresholds. In addition, a threshold related to the reprojection error and focal length is introduced to accelerate the convergence speed when the proportion of outliers is low. Finally, the maximum value of two thresholds is selected to weight the objective function, which reduces the influence of outliers on the estimation. The experimental results show that the method improves the anti-outlier ability of the orthogonal iterative algorithm and performs better in robustness.

Aiming at the problem of efficient target 3D point cloud segmentation in polarization-modulated 3D imaging system, an efficient segmentation concept of multi-dimensional information fusion is proposed. The system uses a high-resolution EMCCD camera as a planar array detector, during an imaging cycle, the gray image in the field-of-view and the 3D point cloud data can be obtained simultaneously. According to the imaging characteristics, the point-to-point mapping relationship between pixel coordinates of gray image and pixel coordinates of point cloud data is established. Combining with the image edge segmentation method by using particle swarm optimization algorithm, the coordinate information of the target after segmentation is mapped to the 3D point cloud data, so its 3D point cloud data is obtained. In this method, 3D point cloud data processing is reduced to 2D image processing, which significantly reduces the computational complexity and avoids the influence of distance noise on segmentation accuracy. The effectiveness of the method is verified by experiments.