In order to evaluate the performance of the convection turbulence simulator, the stability of the simulate turbulence is tested and the credibility of the turbulence simulator is improved. The measurement and analysis are done from three aspects of regional stability, wavelength stability and frequency stability by using specific instrument. 21 points in specific locations are chosen for testing the regional stability of scintillation and angle-of-arrival. By using the coherence length as the indicator, 532 nm, 808 nm, 1064 nm and 1550 nm lasers are used to test the wavelength stability of the convection turbulence simulator. Finally, the spectra of scintillation and angle-of-arrival are analyzed to test the spectral stability of turbulence simulator. The experimental results show that, the performance fluctuation of the convection turbulence simulator in a 16 cm ×16 cm area is less than 15%, the coherence length fluctuation under four wavelengths meets Kolmogrov theory and the spectrum fluctuation is less than 20%. The turbulence simulator can simulate the atmospheric turbulence with high precision, high reliability and high stability. The research provides a strong support for the applications of the convection turbulence simulator.

The surface morphology and deformation depth of the copper targets treated by nanosecond laser shock peening (LSP) are measured by optical microscope (OM), 3D profile and so on. Non-contact optical profile is used to measure the surface roughness of the metal targets. The source of micro defects is analyzed emphatically when absorption layer is aluminum foil tape. Samples with different surface roughnesses are treated by LSP. Experimental results show that there will form macro dents and micro convex-concave structures on the impacted regions when black paint is used as the absorption layer. When the absorption layer is aluminum foil tape, besides the macro dents, there will form large amounts of micro defects on the impacted region. Through analysis and experimental research, it is confirmed that the formation of micro defects are associated with the air bubbles existed in the glue on the back of aluminum foil tape. LSP can increase the overall roughness but reduce the maximum height of roughness when the original roughness is high. When the surface smoothness is high, LSP can increase the overall roughness and the maximum height of roughness.

A time focus and time collimation system is presented in this paper. It consists of time focus system, time collimation system, streak tube, pulse generator and CCD. Time compression ratio of the system to electron beam is measured. While gradient of the focused pulse is 800 mV/ps, measured time compression ratio is about 3.4∶1. Relationship between time compression ratio and gradient of the focused pulse is obtained. The measured results show that time compression ratio increases with the increase of the gradient of focused pulse.

In order to realize the functions of illumination and communication of the visible light communication (VLC) technology, pulse position modulation (PPM), color shift keying (CSK) and hardware algorithm field programmable gate array (FPGA) are combined to verify experimently the proposed RGB chaotic pulse position modulation (CPPM) based on RGB LED application. The constant current drive circuit at the transmitting terminal, the optical antenna module, LED heat management and each signal-processing circuit module are designed in the system. The circuit performance is verified by testing. The parameters, including waveform, bit error rate (BER), illumination and others, are analyzed. The feasibility and practicability of the system are validated.

A bend-resistant large-mode-area dual-mode photonic crystal fiber is proposed. The transmission properties are analyzed with full vector finite element method combined with perfectly matched layer boundary conditions, and the variation of bending properties with the bending radius and bending orientation angle are discussed. By optimizing the structure parameters, the fiber can only transfer the fundamental mode HE11 and second-order mode HE21 at a wavelength of 1550 nm. When the fiber is in a straight state or the bending radius is 35 cm, mode field area of the mode HE11 and HE21 are greater than 1000 mm2, and the bending loss is lower than 0.075 dB/m. Besides, the fiber can effectively inhibit the decrease of mode field area that results from the bending deformation. The minimum bending radius can reach 10 cm, and the bending orientation angle can be extended to ± 180° . The designed fiber with large mode area, low bending loss and low sensitivity of bending orientation has important applications in high power optical communication devices.

In order to meet the measurement requirements of gas turbine tip clearance, the displacement optical sensor with two-circle reflective coaxial fiber probe is designed. Output functions of the fiber sensor without and with collimating lens are gained based on light intensity coupling principle analysis. The effect of lens on reflective optical fiber displacement sensor characteristics is analyzed. Then, effect of transmission efficiency and interference on measurement results is evaluated. The static measurement and smog interference experiment of the sensor with and without collimating lens are completed. The results show that the linear measuring range of the sensor designed is 2.6 mm, and the antipollution ability is proved. It provides a reference for the application of reflective optical fiber displacement sensor in gas turbine tip clearance environment.

An intrinsic Fabry-Perot interferometric fiber sensor is successfully fabricated by normal single mode fiber and multimode fiber with different outer diameters. Its temperature and pressure response performance is investigated. The pressure responding theoretical model is got by materials mechanics theory and photoelastic theory. Considering the strain direction caused by Poisson effect, the multimode fiber with small diameter is used to improve the pressure sensitivity. In experiments, the diameter of multimode fiber is 120 mm after the fiber is corroded by hydrofluoric acid. The temperature responding experiment is done by this sensor with varied temperature from 20 ℃ to 500 ℃, with 1 mm cavity length. The experiment results show the sensor have a good temperature linear response and repeatability. The temperature sensitivity is 25 nm/℃ . The pressure experiment results are also got at 20 ℃ temperature. The experiment results show the sensor also has a good pressure linear response. The pressure sensitivity is 4.7 nm/MPa in this experiment. This kind of optic fiber sensor can be well responded by temperature and pressure, and with the potential of multiplexing sensors.

Considering the conventional multi-pulse position modulation (MPPM) in free atmosphere optical communication, a hybrid MPPM modulation scheme based on modified binary phase shift keying (BPSK) is proposed. In the scheme, BPSK-modulated optical pulses are transmitted in a BPSK-MPPM hybrid frame and as the transmitted information is carried by both position and phase of the transmitted pulse, the change of optical pulse position is used to transmit more bits. The modified system model, channel transmission characteristics, bandwidth utilization, transmission efficiency and channel capacity are researched and measured, which are also compared with those of traditional schemes. Simulation results show that bandwidth utilization and transmission efficiency of the proposed scheme are higher than those of the ordinary schemes. In addition, the channel capacity in the hybrid MPPM frame construction including protected slots is also higher than that of the ordinary schemes.

With the extensive application of liquid crystal spatial light modulator, using liquid crystal spatial light modulator to generate vortex beams become more and more practical. Due to defects in the production process of reflective liquid crystal spatial light modulator, the quaility of the vortex beams generated by the reflective liquid crystal spatial light modulator is not perfect. An aberration compensation method based on Gerchberg-Saxton (GS) phase retrieval algorithm is put forward to overcome this shortcoming, after this aberration compensation, the quality (symmetry) of the vortex beams is improved. Furthermore, the method for the reflective liquid crystal spatial light modulator to generate all kinds of perfect vortex beams is explained in theory.

Low-coherence digital holography is confined to in-line holography because the interference fringes could be observed only when the angle between the object and reference light is small enough. Therefore, phase-shifting technique is usually employed. But it is not fit for dynamic analysis for demanding more than one hologram. However, the reconstructed image according to different sections of the object will be disturbed by the twin image and the out-of-focus section image by employing the traditional numerical reconstruction method for the analysis of one single in-line digital hologram. A numerical reconstruction method according to compressive sensing theory for the analysis of single low-coherence in-line digital hologram is proposed. By this method, the twin image and the coherent noise can be inhibited. The theory is presented in detail. Experimental research on light emitting diode-based digital holography is performed to demonstrate the feasibility and validity of the method.

A scheme of three-dimensional (3D) object encryption and display based on computer generated hologram (CGH) and random phase is presented. In the scheme, according to the reconstruction system of three-dimensional objects, the random phase masks (RPMs) are embedded into spectral information of CGH, then the encrypted CGH (En-CGH) is obtained. When the En-CGH is decrypted, the conjugate random phases as the keys are placed in the right position, and the decryption and reconstruction of three-dimensional objects are realized. The system structure of this scheme is simple. The introduction of RPM improves the security of reconstruction system. The efficiency of the encryption and the capacity of information storage are both improved. The numerical simulation verifies the feasibility of the scheme.

Based on the principle of radiation temperature measurement, the theory of temperature measurement with infrared thermal imager is introduced, in order to improve the measurement accuracy of molten steel, an experimental platform is built, the infrared image of molten metal under different temperature are obtained. Through the wavelet denoising method for infrared image with high signal-to-noise ratio, display temperature and morphology is obtained by using Matlab software, which can reproduce the molten pool surface temperature field real, so as to achieve the requirements of measurement accuracy and design. This method lays a strong foundation for molten metal on-line infrared temperature measurement.

Based on the model of laser imaging radar detecting target, the trajectory forming process of target imaging points is analyzed, and the distribution function of echo peak points on the image surface under single pulse imaging. While the experiment is designed, a method of detecting target three-dimensional trajectory is put forward. The experimental image obtained by laser radar is processed through the adaptive thresholding algorithm, and the trajectory of target imaging points is got. Then the comparison between theoretical and experimental data is made, and the result shows that the relative error between trajectories detected by theoretical model and experiment is controlled in 2%, which has a better coincidence. The result can provide reference for the trajectory prediction and intention judge of aerial target.

As the data volume of point clouds obtained by means of the laser line scanning mode is very large, and not convenient for storage, processing and analysis. A simplified expression of point cloud data based on vector angle computing as well as the corresponding STL file generation method is introduced. The proposed method can not only reduce point cloud data efficiently, but also reserve the integrity of the original data object information by retaining key inflection point data of the related object. Different from common generating method of the STL file, the gap and distortion between triangles are avoided by the STL file generation method based on adjacent points analysis and is of great applicability and practical reference value.

In hue, saturation and value (HSV) color space, an effective remote sensing image fusion algorithm is proposed combining with simplified pulse coupled neural network (S-PCNN) and two-dimensional stationary wavelet transform (SWT). The multispectral transformed into HSV color space, the multispectral V component and the panchromatic spectrum are decomposed by two-dimensional static wavelet decomposition, and the decomposed high-frequency coefficients is put into S-PCNN model to fuse.The low-frequency coefficients are decomposed second time and fused with different rules, the fused V component is obtained through wavelet inverse transformation for fused wavelet coefficient, the multispectral H, S components and fused V component are transformed into RGB space. Through a group of common remote sensing images experiment, the results show that the fusion effects of proposed algorithm is better than the traditional algorithms, and the fused image contains lots of detail, color. It is an effective remote sensing image fusion algorithm.

For fog-degraded images, a new method of restoring polarization image is proposed. Estimate the atmospheric light intensity and transmission rate function are estimated, and the transmission rate function is optimized to realize image defogging based on atmospheric scattering model for three random angle polarization images. Polarization image restoration quality of 3 random angles and 2 orthogonal angles are compared in this experiment. Experimental results show that the proposed algorithm improves the image′s definition and contrast, and effectively improves degraded images in the haze condition. The angles of 3 polarization images are arbitrary. It is not necessary to carry on the registration of the polarization angle, and beneficial for the practical application of the engineering.

As an important resolution enhancement technology (RET), off-axis illumination (OAI) can not only improve lithography resolution, but also improve depth of focus (DOF) to some degree. Finding a best OAI mode to improve lithography performance for specific mask pattern is the main research content. The best OAI mode is obtained through optimum design method, using the steepest descent algorithm as the optimum method, and using process window as the evaluation function. The process window contains three information: image fidelity, exposure latitude and depth of focus. The three aspects are described by performance of aerial image, and the three functions are weighted to get a comprehensive evaluation function. The complex photoresist model is avoided, and the evaluation function value can be obtained quickly and accurately by the propsed method. The optimal OAI modes and actual process window are solved for different weights, and the results show that the actual performance of process window can be reflected by evaluation function described through aerial image, and the performance of process window can be improved greatly by using the optimal source obtained by selecting right weight.

A high precision Levenberg-Marquardt (LM) iterative algorithm for the analysis of fluorescence lifetime imaging microscopy (FLIM) data is reported. The performance of this method was tested on the time-resolved fluorescence intensity images of fluorescence lifetime standard dyes and real biological images. The method is applicable for various fluorescence decay functions and has better estimation precision based on iterative nonlinear least squares minimization algorithm. It indicates that the LM iterative technique for FLIM analysis represents a precise and versatile method that enables practical applications of FLIM in biology, biochemistry, biophysics, and medical diagnosis.

A light-field three-dimensional (3D) imaging systems based on holographic directional scattering-screen is developed, which is able to realize light-field 3D display of real scene and virtual scene. The viewpoint image and the generation method of projected image under holographic directional scattering are detailedly analyzed. The camera calibration algorithm and projector display calibration algorithm are developed, and hardware design and software development of light-field 3D acquisition and 3D display are achieved. Light-field 3D imaging of both real scene and virtual scene are completed in the experiment, and the results of which demonstrate the proposed system is feasible. Meanwhile the results also prove the generation method of projected image and the calibration algorithms are correct.

Stray light is one of the important factors affecting the image quality of microscopy systems. During the processing of optical elements, stray light caused by specular scattering can not be ignored. Taking microscope objectives with 20× magnification and NA=0.49 as a typical example and using the optical analysis software TracePro, a simulation model of measuring veiling glare of microscope objectives is built up. Through analyzing the factors affecting the model with different illuminance numerical apertures, different illuminance fields and different black spot positions, the feasibility of the model is verified. On this basis, the stray light intensity on the image plane with different NA microscope objectives is simulated quantitatively under the condition of different surface roughness (2, 5, 10, 20 nm) and different cleanliness levels (250, 500, 750). The results indicate that the surface roughness greater than 10 nm and the cleanliness level higher than 500 will change the stray light intensity distribution on the image plane, and affect the system performance significantly, especially for those microscope objectives with large NA. It is of critical importance to keep the surface of optical elements clean and to improve the processing technology of optical elements.

Measurement of atmospheric wind field is very important for national safety, weather forecasting, aerospace and military applications. At present, our country is lacking of the comprehensive measurement capability of large-scale wind field. Light detection and ranging (LiDAR) is the sole instrument to access the three-dimension wind field profiler directly. The proposed space-based coherent Doppler wind LiDAR accesses the target Doppler frequency shift and calculates its line-of-sight velocity using laser heterodyne technology. Comparing with the traditional LiDAR, it has the prominent features of high space-time resolution and high sensitivity in dimension, especially in weight and power consumption. Illustrations focus on its principle and key technology. The intending space-based feasibility and prospect of the proposed coherent wind LiDAR are also given.

A novel three-dimensional profilometry technique by optical fiber interference projection is presented. This technique uses fiber laser interference fringes with fine sinusoidal property as carrier fringes to project. Take the wavelength-modulated laser as the light source to make the purpose of interference fringe phase-shift by accurately changing the current. The phase and three-dimensional (3D) profile of object can be calculated by the phase-shifting algorithm. In this experiment, the repetitive deviation of object diameter under 50 mm is less than 30 μm root-mean-square by using overlapping averaging 4-frame algorithm.

High-strength steel E36 and stainless steel 304 are welded by laser welding with the same line energy. Microstructure and fracture morphology of welded joint are investigated by means of optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the mechanical properties of the weld are evaluated by micro-hardness and tensile strength testing. The results show that both heat input and laser power density play a crucial role in macro-morphology of welded joint. Welding speed has a significant impact on micro grain morphology. Weld zone is made up of martensite and some carbide particles. There are mainly austenites and a bit δ -ferrites on the 304 fusion zone while lath-shaped martensite, bainite and ferrites are produced on the heat affected zone of E36. When the laser power is 1 kW, micro-hardness of the welding seam is lower than that of the others, and the tensile specimen break occurs at the seam, while the other specimens occur at the side of E36.

The forming of thin-walled parts by laser cladding results in creation of uneven cladding layers that manifests itself in poor surface. Furthermore, it makes follow-up forming difficult. In this case, it becomes necessary to conduct auxiliary mechanical milling and polishing. However, laser forming is one quench solidification process that results in high hardness which makes machining of these hardened surfaces impractical. In addition, if the shape of parts is complex, the finishing machining operations will require multiple jigs and fixture setups which are time consuming and highly inefficient. In fact, the finishing machining operations can account for more than 60% of the entire manufacturing cycle. To overcome the difficulty, a new composite precision rapid prototyping method is proposed. This new method is based on machining the cladding part by laser milling. The proposed high performance and precise approach results in greatly improved surface quality, as measured by surface morphology, as opposed to the traditional laser cladding forming. Furthermore, it will eliminate the need for the post processing and reduce the processing time and ultimately the processing cost of the part.

Processing of alumina ceramic substrate by laser scribing is introduced, and alumina ceramic surface gasification threshold of laser processing is analyzed based on the three-dimensional heat conduction model. A laser processing experimental platform used for alumina ceramic substrate is built with a Coherent E400 radio frequency CO2 laser and an IPG YLR-150/1500-QCW-AC fiber laser. 96% alumina ceramic substrate with the thickness within 1 mm is used for cutting and scribing experiments. The processing results are compared. During the experiment, in fiber laser continuous wave mode, breaking problems during cutting and scribing are solved by using absorbent on the ceramic surface and nitrogen as auxiliary gas. The experimental results show that 96% alumina ceramic substrate with thickness within 1 mm can be processed by cutting and scribing by using air as auxiliary gas without absorbent and with appropriate technology parameters in the qwasi-continuous wave mode.

The morphologies of silicon surfaces are modified with the single Nd:YAG nanosecond laser pulse (wavelength 532 nm) in the air and water. The influence of laser induced plasma shock waves in the medium/silicon interface on silicon surface topography is studied. The shock wave mechanical signals are gathered by piezoelectric sensors and the morphology of silicon surfaces is observed by scanning electron microscopes (SEM). It is found that at the same energy level, the average speed of the underwater shock wave generated by irradiating the silicon surface under water is 1.5~2 times higher than that in air, and the mechanical strength under water is about 10 times higher than that in air. By observing the silicon surface morphology, it is found that many raised bulbs and recessed holes appears at the center of the craters on silicon surface under water, with corrugated structure but no sediment at the edges. While the center of the craters on silicon surface in air are relatively smooth, with circles of sediment at the edges. Thermal-mechanical effect induced by plasma shock waves generated at the medium/silicon interface is the main reason of silicon surface topography formation. Under water, greater mechanical strength of the shock wave induced by restriction effect of water, and explosive boiling thermal phenomena result in completely different topography as compared with those in air.

The mode field distributions are studied by using plane wave method. The influence of periodic structure, point defect and line defect on mode field distribution are discussed in detail. The results reveal that the mode field is a plane wave along k-direction modulated by a periodic function, just as indicated by Bloch theorem; the mode field is changed with k even with one band; mode field mainly locates in the areas of high dielectric constant, and shows a high degree of symmetry; mode fields in neighboring bands are orthogonal except those degenerate bands; the mode field shapes are relation with the lattice structure, the square lattice show square shape; the mode field distributions are different for different defect radius. Mode field distribute in the defect and its surrounding area and shows significant period symmetry.

The propagation performance of a low amplitude one-dimensional screening bright soliton in photorefractive media is studied in this paper. Numerical simulations show that, the beam would present linear diffraction in the isotropic media. While in the anisotropic nonlinear media, without taking the diffusion effect into account, the input beam would keep shape and be a line in the transmission direction. The beam would be selfbending when considering the diffusion effect. What′s more, the direction and degree of self-deflection are related to the temperature. At last, The relationship between self-bending distance and the temperature is analyzed. At a special temperature, we can get the biggest distance and the deflection distance can be controlled changing the temperature.

The traditional traceable thermocouple dynamic calibration system uses CO2 laser as the light source, which has the characteristics that laser light energy distribution is not uniform , the adjustment of optical path is inconvenient and heated uniform of the sensors cannot be guaranteed. The light source of semiconductor laser had stable and uniform output light spot, but the divergence angle is large. In order to simplify traceable thermocouple dynamic calibration optical design, control the laser light path more convenient, and ensure the uniform heating of the thermocouples, the appropriate fiber optic and lens coupling are selected using Zemax software to improve the light path. The results show that the design greatly reduces the difficulty of light path adjustment, improves the efficiency of the laser, and provides high quality laser source for the traditional traceable thermocouple dynamic calibration system.

Regarding to picosecond pulse laser as the laser source used in long-distance ranging, a detail discussion is addressed. With the review of laser pulse ranging and the development of remote laser ranging, we present an idea that picosecond laser pulse is used in long-distance ranging. We briefly introduce the application of picosecond pulse laser in satellite laser ranging, and then analysis the possibility of picosecond laser pulse to be used in long-distance range finder. We design a simple picosecond laser pulses remote laser rangefinder system.

In order to meet the demand of mobile phone market for the thin and wide-angle mobile phone camera, a thin and wide-angle for 8 mega-pixel mobile phone lens is designed by Zemax. The mobile phone lens is composed of 4 plastic aspheric lenses and a infrared filter, which has a total length of 3.6 mm, a field of view of 82°, a F-number of 2.1, the distortion is less than 2%. It can be used in OV8858 which is a 8 mega-pixel sensor with 1.12 mm pixel size made by Omni Vision, Nyquist frequency is 446 lp/mm, the maximum pixel is 8 million and the maximum image height is 4.57 mm. The design result shows that modulation transfer function (MTF) value at frequency of 224 lp/mm is larger than 0.25, and the maximum TV distortion is lower than 1%. After tolerance analyze, the lens has the high quality of image and good performance. The simulation by ASAP shows that the flare of the lens is slight and acceptable.

In a rectangular light emitting diode (LED) array, by symmetry analysis of illuminance, a segmented illuminance profile of a light unit is presented to build free-form lenses for direct panel lights′ uniform illuminance. Each light unit is composed of an LED element and a rotationally symmetrical free-form lens, whose refraction index is 1.4935. A square array of LED direct panel light with a distance-height ratio of 4.1 is given as a goal, then the freeform lenses are built by energy distribution design methodology, and the optical simulation results show that the uniformity on the target screen is greater than 0.85, and the optical effect is higher than 0.9. This method can be applied to the extend light sources. The limit of illuminance uniformity of the direct LED panel lights mentioned above can be achieved by using the symmetrical analysis method which is useful for the optical design of LED panel lights.

HAT-CN/CuPc is adopted as hole injection layer (HIL) in organic light-emitting diodes (OLEDs). While this combination is inserted in the ADN blue device, the driven voltage is lower down efficitively without losing the current efficiency. This result is caused by two reasons. The one is the improved crystallinity of CuPc film that is induced by the HAT-CN thin film, which can decrease the electric resistance of HIL effectively. And the other one is the efficacious hole injection efficiency that is achieved by HAT-CN/CuPc. The turn-on voltage of HAT-CN/CuPc device can reduce to 3.4 V, which is 0.5 V lower than that with CuPc as HIL.

improved plasmonic dichroic splitter based on three and four subwavelength metallic slits metal-insulator-metal (MIM) stuctures is proposed. Different visible lights passing through the multi-slits structure produce optical splitting effects by filling with different insulators and setting the slit width, thickness of the waveguide structure of multi-slits. The splitting effects are explained by using surface plasmon's principle and classical optics interference principle. Numerical simulation by the finite-difference time-domain (FDTD) method is conducted to verify the design. Compared to two subwavelength metallic slits structure, the higher splitting ratio can be achieved in multi-slits structures. Those MIM designs due to the advantage of simple structures can be obtained by using experimental equipment such as electron beam lithography. Therefore, it has good application in integrated optics and optical communication fields.

Spaceborne full waveform laser altimeter for space remote sensing has the advantage of high precision and more information. Simulation and analysis of spaceborne full waveform laser altimeter have become a valuable tool for system design and evaluation. Modules of simulation have been proposed according to research on spaceborne full waveform laser altimeter. Transmitter model, target model and receiver model are established for simulation of full waveform echo signal. Full waveform data are simulated using a square sampling process taking no account of influence of atmosphere and difference of reflection. Moreover full waveform data are processed for parameter calculation. Laser echo calculated by each module will be estimated before system design which is useful for system design and full waveform data process.

Scanning beam interference lithography (SBIL) is advantageous to produce large-area linear diffraction gratings that are phase-accuracy to nanometer level. In order to comprehend the merits of SBIL, the research progress on SBIL both in China and abroad are introduced, and the key technologies in SBIL are summarized from the merits and limitation of the scheme and principle. And then for the application of the specific grating, parameters of the key technologies in SBIL are presented. The development of SBIL is forecasted.

To define the biophysical pathways of cellular life and to elucidate the molecular mechanisms that carry out cellular and biological functions is one of the current significant scientific challenges in the intersection field of life and physical sciences. The novel application of optical techniques, sensing physiological changes in the details of individual cells, can help to meet these requirements. Bacterial spores belong to a cell type responding to adverse growing conditions, and the germination of spores from dormant to vegetative state is a special process of physiology. The application and development of optical techniques and single-cell analysis has played an extremely important role in understanding the mechanism of spore germination and heterogeneity. Raman spectroscopy, differential interference contrast microscopy, fluorescence imaging and Raman imaging are reviewed, and major unanswered questions are also discussed.

The research progresses of the gas sensors based on microfiber evanescent field effects are summarized. Meanwhile, the sensing principle and faced problems are explained. The research progresses of three kind structures gas sensors based on microfiber evanescent field effects, such as just depending on microfiber evanescent field effects, coating sensitive film on the microfiber surface, and combing with other optical microstructure, are focused. Although some research results have been achieved, many problems and challenges are facing. We believe that with developing of the research, owing to their unique performance advantages, the gas sensors based on the microfiber evanescent field effects are still possible to become a strong competitor for the existing gas sensors.

In infrared imaging system, crosstalk reduces definition of the image, affects the resolution performance and the imaging quality of focal plane array. Therefore, it is necessary to study the test and generation mechanism of crosstalk. Three types of testing methods and principle of crosstalk effect are compared, generation mechanisms are elaborated from two aspects of optical crosstalk and electrical crosstalk, and solutions of crosstalk are systematically summarized. At the same time, the future development trend of the infrared imaging device are also discussed. In order to offer beneficial reference for improving the relative device technology, structure and manufacturing process.

The research progress of fabrication and application of doping black silicon via femtosecond laser irradiation is reviewed. The formation mechanism of micro-nano structures of silicon surfaces and impurity band in black silicon is introduced, and the influence factors in fabrication process of black silicon is analyzed, elaborating that super saturated doping can be realized by introducing chalcogen dopant (sulfur, selenium, tellurium) in the background gas, liquid, solid thin film environments, or ion-implantation followed by irradiation with femtosecond laser. Some problems demanded to be solved are suggested, and the application prospects of doping black silicon are predicted.

Optical coherence tomography (OCT) endoscope is a new optical imaging technology, which combines OCT with the medical electronic endoscope. With the rapid development of OCT, the endoscopic technology based on OCT becomes a popular research area for its micron level resolution and non-destructive real-time imaging. The basic principles and classification of OCT technology as well as several important parameters of OCT technology including the probing depth, axial resolution and lateral resolution are mainly introduced. Some recent research achievements and development of endoscopic OCT scanning probes are discussed, and the endoscopic OCT scanning probes are compared in terms of outer diameter, scanning speed, axial resolution and lateral resolution. The applications of side-imaging OCT probes in gastrointestinal tract, respiratory tract, blood vessels and other organs as well as the applications of forward-imaging OCT probes in ovaries, breast, brain and other organs are summarized.

The functional near-infrared spectroscopy (fNIRs) is a new convenient non-invasive optical imaging technology to explore human brain activity through cerebral hemodynamics within human brain. However, the fNIRs signal is susceptible to interference induced by human relative motion and physiological activity. The interference can damage the quality of signal, so it is important to develop approaches to eliminate the motion artifact and physiological interference from fNIRs signal. Brief introduction to current development of fNIRs signal processing techniques to correct the signal contaminated by motion artifact and physiological interference is given. The current problems of fNIRs techniques, some promising research fields and the correlation between fNIRs and functional magnetic resonance imaging are discribed. A brief conclusion for fNIRs signal processing techniques is obtained.

Madagascar is now the most important origin of sapphire all over the world. Aiming to analyze the coloration mechanism with ultraviolet-visible absorption spectrum and X-ray fluorescence (XRF) and to explore the heat treatment process of low quality sapphires from Madagascar, the sapphire samples are treated at 1300 ℃~ 1600 ℃ for 12~20 h in the air, most of the samples become light ones with weaker Fe2+/Ti4+ charge transfer, and some samples show fine color in blue with the decline of Fe3+ and increase of Ti4+.

Extreme learning machine (ELM), as a kind of single hidden layer feedforword neural networks, is an important tool in big data analysis. Compared with traditional neural network methods, it has simple structure, high learning speed and good generalization performance. However, the output weight of ELM is estimated by the least squares estimation (LSE) method, and thus ELM network lacks of robustness since LSE is relatively sensitive to outlier. A new robust ELM based on least absolute deviations (LAD) regression, called LAD-ELM, is presented. Moreover, the proposed LAD-ELM is posed as a linear program with global optimal solution. Furthermore, the proposed LAD-ELM is directly used for near-infrared (NIR) spectral analysis, and an analysis system for hardness of licorice seeds is built based on LAD-ELM and NIR data. Compared with the traditional methods, the experimental results in different spectral regions show the feasibility and effectiveness of the proposed method. Moreover, the investigation provides theoretical support and practical method for studies on licorice seed hardness using ELM and NIR technology.

Optical emission spectroscopy (OES) is an effective method for plasma measuring and diagnosing. OES is used to in-situ measure the hot filament chemical vapor deposition (HFCVD) plasma of acetone/H2/Ar system and methane/H2/Ar, respectively. The type, intensity and the influence of carbon source classes, especially the pressure for acetone/H2/Ar on the spatial distribution in HFCVD plasma are investigated. The results show that main groups are basically the same under different carbon sources, but the differences of spectral distribution are obvious. In acetone system, the intensity of CH is the largest, and there is no H2 spectral lines. Ha line decreases with increasing the pressure, and other groups have a maximum value at nearly of 3.5 kPa. However，in methane system, H2 spectral line is obvious and the intensity of CH is the largest. Ar groups in two systems appear differently in spectral peak corresponding to the wavelength, which is 433.36 nm in acetone system and 794.8 nm in methane system.

As one of the most important ways to calculate the plasma temperature when the laser induced plasma is under local thermal equilibrium condition, the use of Boltzmann algorithm is extended. The experiments prove that the soil laser induced plasma is under local thermal equilibrium condition, then the Boltzmann plot is built by several Fe atomic spectral lines. According to the fitting line, the intensity of other Fe spectral lines are calculated and the error between the calculated and the experimental results is lower than 15%. The characteristic spectral lines of Fe, Ti, Ca in soil are abundant and easy to overlap with other spectral lines. The method can assist identifying and separating some unknown spectral lines. By building the Boltzmann plot of Mn, the intensity of 405.89 nm line is calculated and its impact on the Pb 405.78 nm line is studied. The results show that this method can be applied in the field of spectral line identification and separation.

In recent years, there is growing concern for the environment pollution. Trinitrophenol (TNP), an important environmental pollutant and dangerous substance, is rarely studied for its detection. Raman spectra and surface-enhanced Raman scattering (SERS) method are used to study TNP for its Raman characteristic peaks and vibration modes. SERS spectra of TNP are studied by using gold and silver colloidal nanoparticles as SERS substrate. It is found that the gold colloidal nanoparticles are suitable SERS substrate which can significantly enhance Raman signal of TNP. However, it is ineffective to use silver colloidal nanoparticles. The experimental results show that it is basically linear relationship between the concentration of TNP sample and its SERS signal when gold colloidal nanoparticles are used as the SERS substrate. It is of great significance for further quantitative detection and identification of substances in complex systems.

Photophysical and photochemical reactions of air pollutants induced by sunlight radiation, particularly volatile organic contaminants (VOCs), have serious damaging effects on atmospheric environment. Via femtosecond pump-probe technique and photoelectron imaging detection technology, these photophysical and photochemical reactions in the femtosecond time scale and molecular space scale aretracked. Detailed dynamics are obtained for understanding, which are significant for further protection of the atmospheric environment. Combining with the results of nearly three years in the direction, the research progresses of this direction are summarized. The doublesided photoelectron imaging setup and experimental platform for these measurements are described. Several recent experimental results are introduced: ultrafast relaxation dynamics of the excited states of ethylbenzene; ultrafast competing intersystem crossing and internal conversion in the S2 state of o-xylene; photoisomerization dynamics of furan; multiphoton dissociation dynamics of Freon 113.