This PDF file contains the front matter associated with SPIE Proceedings Volume 12448, including the Title Page, Copyright information, Table of Contents and Conference Committee list.

Compared with traditional measurement of structural vibration, which requires a limited number of sensors to be distributed discretely on the surface of the structure, vision-based vibration measurement makes use of each pixel as a potential measurement point. The increase number of sensors in spatial density by several orders of magnitude, thus achieving high spatial resolution. The machine vision measurement method based on motion amplification is used to measure the micro vibration of structures. The existing motion amplification algorithms rely on pyramid decomposition, which requires multi-scale and multi-direction analysis, and the noise reduction process is complicated. Therefore, to address these issues, this paper proposes a structural modal visualization algorithm based on two-step motion amplification. The visual measurement vibration method based on motion amplification can visualize the vibration mode of the structure under the condition of high resolution. Compared with other methods, we propose a simpler method than the vibration measurement extraction based on phase motion amplification and the blind signal separation of multi-directional steerable pyramids. This method uses singular value decomposition to achieve unified noise reduction of time-domain video in the pixel domain, and amplifies the decomposed signal through Euler amplification. At this time, there is still modal aliasing, and the mixed signal is decoupled. At this time, the separated signal is only related to the single mode of each order, and the signal is amplified based on the phase and the independent vibration mode is visualized. We verify our method through a micro-vibration video of a spherical geometric structure and a cantilever beam excitation experiment, and the results show that the method is effective.

Dissolved oxygen (DO) in water is a key parameter, which represents the purification capacity of water and also creates conditions for the survival of aquatic organisms. Among the existing DO detection methods, most of them adopt on-site sampling and laboratory detection, or arrange sensor network for fixed-point detection, or adopt buoy method for detection. These detection methods are either not precise or accurate enough, or it is difficult to reflect the water quality in real time. It is difficult to meet the current high requirements for water quality testing. This paper proposes the idea of using bionic robotic fish carrying water quality sensor system to realize multi-parameter detection of water quality, which not only gives full play to the advantages of optical sensor detection in accuracy and accuracy, but also gives full play to the good adaptability of fish in water. In this study, a fluorescence dissolved oxygen sensor was used to detect DO in situ. The automatic location of pollution source can be realized on this basis. This research can provide an idea for the detection and research of submarine archaeology and deep-sea mineral exploration, especially underwater in-situ detection.

In this paper, an innovation coherent beam combining (CBC) architecture to generate the structured light beams array was proposed and experimented. The simulation and experimental results reveal that the optical vortex beams array (OVBA) with multi-modes can be generated effectively in the far field. The OVBA is composed of multiple sub-OVB in the intensity distribution. Furthermore, the number of OVBs can be modulated by changing the fill factor of the laser array in the near field. In particular, the performance of a OVBA copier was observed, which may deepen the understanding of creating the structured light fields by CBC technique. The experiment results were in excellent agreement with the simulation results. This work could provide valuable and practical reference on generation and manipulation of high power structured light beams

As the third generation of solar cells, perovskite solar cells have attracted extensive attention because of their relatively simple structure and high theoretical photoelectric conversion efficiency. However, there are still some problems in thin film perovskite solar cells, such as severe light energy loss, less light absorption in the near-infrared region and part of visible wavelength. Without increasing the thickness of the perovskite absorption layer, using the plasmon effect of metal nanoparticles is an effective method to reduce the light energy loss and enhance the light absorption of solar cells. In this paper, the light absorption of two kinds of perovskite solar cells with and without gold nanobipyramids array structure are simulated by the finite difference time domain method. The results show that the light absorption efficiency of the absorption layer of perovskite solar cells with gold nanobipyramids array structure is improved by 42.93%. Further research shows that the local surface plasmon resonance of gold nanobipyramids can produce substantial electric field enhancement, which may be why gold nanobipyramids enhance the light absorption and improve the efficiency of perovskite solar cells. This study provides a new idea to improve the photoelectric conversion efficiency of perovskite solar cells.

Based on the MODIS surface reflectance data, the surface reflectance feature database of different surface types in Hefei and Shenyang was constructed in different seasons. First, the normalized difference vegetation index (NDVI) and blue/red light band reflectivity are used to classify the land surface into three categories: vegetation, bare soil, and ice/snow. Feature parameter fitting is performed on different surfaces, and the bidirectional reflectance distribution function (BRDF) feature parameter database is constructed. According to the definition of black sky/white sky albedo, the corresponding band albedo is calculated, and the narrow band and wide band albedo parameter database is also constructed. Analysing the distribution characteristics of BRDF and the change in black-sky/white-sky albedo (BSA/WSA), the results show that the BRDF on the vegetation surface has an obvious hot spot effect. The BSA/WSA of the vegetation is higher than that of the visible band in the near-infrared band, and bare soil, except Hefei in summer, has the same trends. The albedo of the ice and snow surface is significantly higher than that of the other two types of surfaces.

Rational harmonic mode-locking refers to a mode-locking state achieved at the modulation frequency that doesn’t match the fundamental frequency. In this paper, we investigated and experimentally achieved rational harmonic mode-locking in optoelectronic oscillators (OEO) for the first time through three schemes based on electric amplitude modulator (AM), electric phase modulator (PM), and Mach-Zehnder modulator (MZM), respectively. In the experiment, the fundamental frequency mode-locking as well as the 2nd-order, 3rd-order, and 4th-order rational harmonic mode-locking were obtained, all generating ultrashort microwave pulses with a repetition rate of 95 kHz and a carrier frequency of 10 GHz. Subsequently, the characteristics of the pulse signals generated by different schemes, such as pulse width, pulse amplitude, and spectral width, were systematically investigated. By comparison, we found that the AM-based mode-locked OEO generates microwave pulse signals with higher stability and narrower pulse width; the PM-based mode-locked OEO can excite more longitudinal modes in the cavity but generates signals with more spurious noise; the MZM-based mode-locked OEO has a simple structure and requires lower power of the modulation signal. We believe this paper could provide some reference for the research on the physical mechanism of the mode-locking phenomenon generated in the OEO when the modulation frequency is mismatched.

The electronic and optical properties of InI1-xPx are investigated using the first-principles plane-wave ultrasoft pseudopotential method with the framework of density functional theory. Supercell models for pure InI and phosphorus doped InI crystals with three doping concentrations (4.17%, 8.33%, 12.50%) are set up. The geometry optimization for the four models is carried out. The band structure, density of states and absorption spectra of P-doped InI are calculated and analyzed. The results indicate that the band gap of InI_1-xP_x tends to decrease after doping P atoms. But when P concentration is larger than 8.33%, the band gap will increase. Compared with pure InI, the electron transition energy of P-doped InI decreases and the probability of electron transition increases. The absorption spectra of P-doped InI system red-shifted and the absorption coefficient increases in visible region.

We propose a 1×3 mode multiplexed optical waveguide switch based on phase change material of Ge2Sb2Se4Te1 (GSST). The big refractive index difference between the two state of the phase change material, which is used to realize the mode matching and mode mismatch between two waveguides. For the 1×3 multiplexer waveguide switch transmission, TE0 mode is set as the input and the modes of TE0 TE1 TE2 will be the output. The characteristics of the switch transmission are calculated and analyzed based on the mode dispersion and mode coupling theory, thus, the structure size and coupling length of the optical waveguide switches are determined. The optical switching device is modeled and simulated by the three-dimensional finite difference time domain (3D-FDTD) method. We mainly discussed insertion loss (IL) and extinction ratio (ER) for evaluating the performance of the device. Three output ports of O1 / TE0, O2 / TE1 and O3 / TE2 show low ILs and high ERs, which separately are 1.19dB, 0.148dB and 0.71dB for ILs, and 16.19dB, 17.2dB and 16.19dB for ERs. The work wavelength is set at C-band with center wavelength of 1550nm.

paper we design a vertical waveguide grating coupler based on sub-wavelength grating with highly integration, high coupling efficiency and large bandwidth. A grating always shows multiple diffraction orders with different efficiency, but only a certain diffraction order with high efficiency is very effective for light coupling. The silicon-based waveguide grating is designed and simulated in this paper, which is modelled by using the Finite-difference time-domain (FDTD) method. The coupling efficiency is analyzed and optimized with the structure parameters of the grating period, duty cycle and etching depth et al. The results show that more than 30% of the coupling efficiency is obtained during the optical communication C-band (1530nm-1565nm) and remained more than 50% in the range of 1545nm-1555nm. The parameter tolerance is relatively high with more than 40nm in grating period, more than 100nm in grating etching depth and more than 140nm in grating duty cycle. Such an optical waveguide grating coupler is expected to be used for input and output of optical signal coupling in the field of silicon photonic integrated devices.

The spatial filter is the key component of the amplifier system in ICF high power laser driver. The conjugate lens at both ends and the filter hole in the middle constitute the main optical axis of the amplifier. Filter lens usually needs precise adjustment, and the existing adjustment mechanism is integrated at both ends of the filter, which is inconvenient to adjust and occupies a large space in use. Therefore, a parallel lens adjustment mechanism was designed as an auxiliary tool to realize the X, Y, Z axis translation, Pitch and Yaw adjustment function of the filter lens. The single-side first-order ghost point of the filter lens was used as the reference for adjustment feedback to conduct axial positioning. The combination of open-loop nonlinear iterative learning ILC and closed-loop linear PID control optimized the iterative path of the postures, which can effectively predict external interference and compensate in advance. The experimental results verified the effectiveness of the adjustment mechanism and the posture feedback method.

Using the observation data of various detectors to identify reentry vehicles, heavy and light decoys, and separate debris is a key task in space situational awareness. During the flight, the space targets are always in a rotating or rolling state (called micromotion). micromotion can reflect the physical attribute information such as mass distribution and shape of different targets, which provides important essential characteristics for identifying space targets. Infrared sensor has the advantages of working all day, long detection distance, and small load. The image data obtained by it can be used to estimate the temperature, radiation, and other information, but the research on estimating the target micromotion characteristics from the multi-infrared images is rarely mentioned. Therefore, aiming to solve the problem of micromotion period estimation of space infrared moving targets under long-distance observation, firstly, considering the factors such as flight scene, target shape and micromotion, the infrared radiation and imaging models of space moving targets under micromotion state are established according to the micromotion dynamics, temperature and imaging relationship; Secondly, the period of infrared radiation extracted from multi-frame images is estimated. Through theoretical analysis, it is pointed that the assumption that there must be a similarity between the sample sets sampled by period length is the main reason for the doubling misjudgment of the average amplitude difference (AMDF) function, and there is also a false valley misjudgment problem in AMDF. The cyclic average amplitude difference function (CAMDF) is used to estimate the micromotion period of multi-shape objects, which can not only effectively decrease the double misjudgment of the period but also solve the misjudgment of false valley estimation points. Finally, a semi-physical simulation platform for space infrared dim moving target detection and recognition is designed and built, and the experimental data is used to verify the effectiveness of CAMDF in estimating the micromotion period. The results show that when the signal-to-noise ratio(SNR) of the simulated infrared radiation is greater than 15, the average accuracy of CAMDF is greater than 90%; Experimental data of five shape objects is used to verify the algorithm, and the average relative error is about 6%. It shows that the algorithm can better estimate the micromotion period of space targets.

If the contour of the pen-head sphere is defective,ink leakage may occur.The common size of pen-head sphere is 0.5 or 0.7 mm,and the contour defects of microsphere with millimeter level are difficult to detect by conventional methods.This paper investigates an observation scheme of the contour defects using laser diffraction: The microhole surrounded by three tangent spheres are scanned with laser spots,consider the microhole pattern as the aperture pattern,obtaining the diffraction pattern by machine vision,calculating the angles of the three light rays through the data processing program to determine the difference between the microsphere radii of the measured and the standard microsphere,and calculate the fluctuation amplitude of the level 0 and 1 bright stripes to determine the presence of convex or concave defects.This paper simulates the diffraction patterns of qualified and two adverse products using MATLAB software.The diffraction patterns of the round hole,square hole,and regular triangle hole outputted by the MATLAB program are consistent with the existing research results,confirming the correctness of the MATLAB program.The present protocol enables a scan to detect contour defects of three microspheres at the same time,greatly improving detection efficiency.

This paper describes a control system that integrates the beam alignment subsystem and the parameter measurement subsystem of SGII-A facility based on Tango Controls. This is the first attempt to apply Tango Controls to the control system of a high-power laser facility. The new control system employs a hierarchical structure that consisting of a device layer, a task layer, and a GUI layer. Physical devices of both subsystems are developed into virtual device service software, acquiring data while hiding complex instructions from physical devices. Using the Tango soft bus, task applications collect data from the device layer, process the data, and send commands to control physical devices. By taking advantage of Tango's communication protocol, these applications can provide concurrent access. New client GUIs developed using QT and based on Tango’s unified interface are more convenient and intuitive

Setting false targets is one of the important means of battlefield camouflage. The survivability of protected targets largely depends on the effect of photoelectric deception and jamming of false targets. The comprehensive use of robust image features plays a key role in correctly evaluating the photoelectric deception jamming efficiency of false targets and quickly identifying true and false targets. The existing efficiency evaluation models lack systematic research on the robustness of various image features in different environments. There are common problems of single target background and incomplete consideration of environmental factors, which lead to the instability of the extracted target image features, and then affect the evaluation results. Given the above problems, two kinds of environmental conditions are set: the change of observation distance and the change of atmospheric attenuation intensity. The experimental environment is simulated by an equivalent simulation method. After filtering the target background interference and extracting the target subject image and features, the similarity measurement method is used to calculate the similarity between true and false target subject images. By comparing the changes of gray distribution, contour, and texture feature similarity value, the robustness ranking and change reasons of features under different environmental conditions are summarized. At the same time, experiments are designed to verify the robustness of gray distribution features. The results show that the gray distribution feature has strong robustness, and the combination of gray distribution feature on the battlefield can effectively help officers and soldiers identify true and false targets in a complex environment.

The train wheelset is a crucial part of railway vehicles, and its damage may lead to serious safety accidents. Therefore, it is imperative to detect tread damage timely and accurately. With the rapid development of deep learning, the image detection method based on a convolutional neural network (CNN) has played an important role. Single Shot MultiBox Detector (SSD) is one of the fastest algorithms in the target detection field. The algorithm has achieved excellent results in target detection, but there is a low recognition rate for small targets. Therefore, we propose an improved SSD target detection algorithm. The Original SSD algorithm is ineffective in detecting small targets with pits and cracks, so conv3-3 is selected to join the detection. We optimize convolution kernel parameters; the convolution layer contains more small target details. Compared with the original SSD, the Mean Average Precision (MAP) of tread defect is improved by 4.38%, and the MAP of small target detection is enhanced by 7.24%. This algorithm has a better performance in detection accuracy.

Foreign fibers in cotton have serious adverse effects on the quality of textile products, so its effective identification and elimination has important significance and social value. To solve the above problems, we propose a fusion image pretreatment method based on limited contrast adaptive histogram equalization ( CLAHE ) and wavelet analysis ( WT ), The collected cotton polarization images were processed by WT & CLAHE, which effectively improved the contrast of anisotropic fibers in cotton images, and laid the foundation for the rapid and accurate identification of various anisotropic fibers in cotton in the later stage, It laid a foundation for the rapid and accurate identification of all kinds of anisotropic fibers in cotton in the later stage. Compared with manual and systematic detection, the results showed that technical personnel and detection system could accurately detect and identify dead leaves, white paper and color paper without interference from external environment and foreign fiber size. For white wool, hair and mulch film due to similar color or shape is small, technical personnel in the detection is easy to miss, and the detection system in WT & CLAHE image pretreatment, white wool, hair and mulch film detection accuracy is obviously due to artificial detection, especially for the mulch film this is not easy to detect foreign fiber has good recognition effect.

This paper presents an integrated system for generating and collecting pulse-interval coded laser effectively. The system realize the generation of coded laser with either fixed-frequency or 3-10 bits pulse-intervals, the coded laser is collected and processed by our system using the memory segment technique. The whole system is highly intelligent based on LabVIEW software and potential for laser guided weapons and laser warning systems.

Laser beam propagation in the atmosphere is inevitably affected by turbulence and extinction, the far-field intensity distribution of the spot changes greatly relative to the laser exit. When the beam quality parameters are measured by the traditional method, the atmospheric effect is difficult to remove and the analysis mechanism is complex. Since the Hartmann-Shack wavefront sensor can detect the wavefront phase of the laser beam. The far-field situation of laser beam can be obtained by processing the phase information of near-field, which can be applied to the diagnosis of laser beam quality. However, for the wavefront distribution of large aperture spot, especially the wavefront distribution of high power laser, the traditional Hartmann-Shack wavefront detection method is no longer applicable due to the limitation of aperture size and the anti-damage detection threshold of detection components. In this paper, a wavefront direct measurement system based on Hartmann detection principle is proposed, which can measure large aperture and high power laser beam. The simulation results show that the wavefront recovery error of our method is low in a large detection range. The performance of this method is also evaluated on a more complex wavefront, and the wavefront recovery accuracy is lower than 0.20λ. The system proposed in this paper is suitable for large aperture laser beam measurement. It is of great importance to improve the measurement accuracy of beam quality.

Numerous studies have demonstrated the importance of obtaining the vertical distribution of turbulence in a time efficient way for evaluating FSO systems and related laser applications, making it necessary to specify the profile of turbulence along the atmospheric propagation path. This paper presents a method for the rapid measurement of near ground turbulence profiles. This method is capable of providing a real-time evaluation of an optical propagation link, making it a useful tool for remote sensing of atmospheric turbulence. Based on this method, a turbulence profile LiDAR has been built in Hefei (31.8°N, 117.3°E) and long-term continuous measurements of the vertical distribution of turbulence were performed from October 2021 to November 2021. The retrieved results of turbulence profiles show that the LiDAR can describe spatiotemporal distributions of turbulence intensity along the measurement path corresponding to the weather and daily time changes.

When the camera imaging method and the detector array method are used to obtain the laser spot image after atmospheric transmission, the image sequence will contain the actual spot image information and the background information of the test system. During the data processing, the image sequence needs to be segmented to eliminate Image background information firstly. Considering that the brightness, contrast, and structure of the images collected by the system will change significantly before and after the laser irradiation measurement system, a method of image structure similarity is proposed to segment the background information of the image sequence. The method of dynamic template is used to calculate the similarity of the light spot sequence, and the similarity threshold is set to complete the segmentation and elimination of the background information of the image. Experiments show that the background segmentation method of image sequence based on structural similarity can quickly and accurately achieve segmentation of background information. The research results can provide a certain theoretical basis and method accumulation for establishing a perfect data processing method in the laser parameter measurement system.

Tight control of the output energy is required in high-power laser devices. The main amplifier provides the most dominant energy gain, whose output needs to be predicted accurately. However, due to its complex structure and time-varying performance, the prediction results using traditional physical model-fitting methods are biased. In this paper, we propose a physical knowledge-based neural network, with an analytical model as the backbone and multidimensional influencing factors introduced by neural networks as input, to achieve accurate prediction. The method combines the powerful characterization ability of neural networks and the interpretability of physical models, which significantly improves the accuracy by considering the coupling effects of several factors and measurement errors. The relative deviation of the method's prediction results improves 65.9% compared to the traditional physical model and 57.9% compared to the pure neural network. The model provides a correction approach for similar problems of oversimplified physical models and can be exploited to aid model development of other measurable processes in physical science.

In view of the large variation of surface curvature of heterogeneous workpieces and the large individual differences of casting blanks, there will be empty stroke and excessive removal when using robots to process according to the manual teaching path, a method combining robot motion and line laser scanning is proposed to obtain the complex 3D morphology of heterogeneous workpieces, which provides the basic conditions for the research of robot self-adaptive grinding. The robot grabs the line laser calibrated by the hand and eye to scan the heterogeneous workpieces, obtains the 3D point cloud data of the workpiece from different perspectives, filters and simplifies the point cloud, then splices the point cloud image with the coarse registration based on FPFH algorithm and the precise registration based on ICP algorithm, and finally completes the 3D reconstruction of the workpiece surface. The reconstructed model is measured experimentally and compared with the actual size of the workpiece, the size deviation of the model is less than 0.1mm, which shows that this method has high reduction accuracy.

Aiming at the problem that the phase jumping point of binocular structured light interferes with phase matching, an improved monotonic zero-setting method is proposed for phase correction. On the basis of the traditional monotonic zero-setting method, the ratio judgment of the absolute value difference between the front and rear phase points and the overall phase fitting slope is added, which effectively improves the phase matching rate. In order to further improve the accuracy of 3D reconstruction of binocular structured light, the influence of the relative distance between the intersection of binocular camera sight and the object to be measured on the same horizontal line below the camera on the accuracy is studied. After reconstruction, the average point cloud height of each position is analyzed, and it is concluded that the optimal distance range between the binocular camera and the object to be measured is near the intersection of the binocular line of sight. The data at different positions and heights of the test are averaged to perform quadratic polynomial fitting to obtain the error function. Through the calculation of the error function, the error is added to the average point cloud as compensation to obtain a new point cloud height. The result shows that in the distance The point cloud error of the 13.141mm reference plane is reduced by 0.026mm, and the point cloud error of 23.897mm from the reference plane is reduced by 0.1mm, which effectively improves the 3D reconstruction accuracy.

In view of the problem of machining stagnation and installation errors caused by the frequent unloading of the tool in the traditional offline inspection method of end mills, which seriously affects the inspection efficiency and inspection accuracy; this paper proposes a telescopic on-machine vision inspection method built on the side observation window of the machining center to realize On-machine inspection of end mill wear which is independent of machining center. For the end mill cutting edge wear detection algorithm, the improved OTSU is used to obtain the binarized image of the worn area, the canny operator and the sub-pixel edge are fused to extract the wear contour, and the original cutting edge is reconstructed by the least square method. Quick detection of end mill wear. The end milling experiment was carried out with the four-tooth carbide end mill as the object to study the nonlinear change of the wear rate of the tool under different wear degrees. The experimental results are in line with the wear change law in the tool life cycle: the wear rate in the initial and sharp wear stages has a large change range, and the change range in the normal wear stage is small; the results show that the measurement deviation of the detection system algorithm is less than 0.01mm, and the average accuracy rate reaches 95.03%, to ensure the accuracy and stability of the detection system.

The wavelength of the detection laser usually used for the target location is different from that of the chief emission laser, so the pointing accuracy is reduced due to the atmospheric dispersion effect. The same is true for the optical axis calibration, and the error can reach half the deflection angle difference. Therefore, to analyze the influence of chromatic dispersion of the horizontal atmosphere on optical axis calibration, laser pointing, tracking, and other related studies in the actual meteorological environment near the ground, based on the spherical stratified atmosphere model, we used the characteristics of the atmospheric refractive index formula changing with meteorological parameters to derive the theoretical formulas for calculating the deflection angle difference of the horizontal atmosphere and emphatically analyzed the diurnal variation of the deflection angle difference through the measuring meteorological parameters near the ground in this paper. The experimental results show that, due to the complex meteorological changes near the ground, the diurnal variation of the deflection angle difference between the center wavelength of 600 𝑛𝑚 near the red light and 400 𝑛𝑚 near the blue light, with the horizontal transmission distance of 1 km is −8 ~ 4 𝜇𝑟𝑎𝑑, which has a crucial influence on the high-precision optical axis calibration, laser aiming and tracking.

To optimize the application of the array fibers in the measurement of large angle laser parameters, the fiber loss is analyzed specifically. And the quantitative method of the actual and available numerical aperture about the fiber is studied, which also represent the allowable incident angle of the laser of the measurement system. Firstly, the theoretical model of fiber loss is constructed, and the influences of incident angle, fiber bend and theoretical numerical aperture on loss are discussed. Secondly, the basic loss, which be seen as the background value, is measured experimentally; by which it is considered that the all-glass fiber with coating and protective layers is suitable for this application. Thirdly, combined with experiment and simulation data, the tolerable bend of the fiber is quantified: when the bend radius is more than 300 times the core radius, the loss can be unaffected by the degree of bend. Finally, how to deduce the actual numerical aperture from the theoretical numerical aperture is discussed. It is verified that there is a good linear correlation between them, and the fitting goodness reaches 0.9970. This paper provides pertinent and effective standards for the selection and arrangement of the array fibers, and offers a theoretical foundation for constructing large angle laser parameters measurement.

Sampling and attenuation of the laser beam to be measured is the first step for detector array target to measure temporal and spatial distribution of laser intensity. Existing sampling attenuation technology is more sensitive to the incident angle of laser beam. In practical applications, sampling angle response characteristics of laser beam can be measured experimentally, and get the coefficient to be corrected. Among them, scattering sampling method is based on scattering parameters of selected sampling material, which can effectively correct sampling angle response in theoretical or simulation stage. In this paper, focusing on angular characteristics of scattering sampling for detector array target, based on bidirectional transmission distribution function, the correlation between the scattering sampling angular characteristics and scattering distribution is derived. Experiments have proved that scattering sampling angle characteristic for detector array target can be expressed in the form of ratio of material scattering distribution function. This characteristic provides a certain guidance for design of scattering sampling angle tolerance for detector array target.

Long term observation of stellar photometer in daytime and night needs to calibrate several stars. Langley calibration observation for numerous stars is a time-consuming job and some stars’ elevation angle suitable for calibration often occurs in daytime, which is not suitable for calibration due to sky background and turbulence. In this paper, a transfer calibration method of different star was realized by the combination of Astronomical Langley observation, stellar apparent magnitude and effective temperature, which is based on the calibration constant of one reference star that would be calibrated by Langley observation. A field campaign was carried out to check the transfer calibration results against two-star method calibration observation by a stellar photometer. Experimental result shows that the transfer method described in this paper is preliminarily feasible, and the method described can be used for stellar photometer real time calibrating.

hotothermal therapy (PTT) is an alternative to surgery, which is commonly used to treat tumors in intracavitary organs. PTT involves heating the diseased tissue with radiation energy, resulting in tumor necrosis. In order to improve the safety and effectiveness of PT, it is necessary to monitor the tissue temperature in real time and regulate the laser power during PTT. Photoacoustic imaging (PAI) is a non-invasive and non-ionizing imaging method with high resolution and high accuracy. Due to the dependence of the thermal expansion coefficient on temperature, the Grüneisen parameter is linearly proportional to temperature, and the variation of the amplitude of the photoacoustic signal is related to the variation of the Grüneisen parameter. In this study, we propose a system for laser dose regulation with photoacoustic signal temperature feedback based on PID algorithm. The pulsed laser is irradiated on the sample surface, the ultrasonic probe receives the photoacoustic signal generated by the sample, and the photoacoustic signal is collected by the oscilloscope and transmitted to the computer, which generates the corresponding command to the heating laser according to the signal and changes the output power of the heating laser. The experimental results show that this method can effectively control the photothermal damage range.

Drug screening is an important step in the development of new drugs. Through appropriate experimental methods and screening models, drugs with specific bioactivity can be transferred from laboratory research to clinical application. Nowadays, traditional efficiency of drug experimentation has been unable to meet the needs of our society. With the rapid development of computer technology, computer-assisted diagnosis and treatment have been gradually accepted and recognized by clinicians and patients. Drug screening process at the cellular level was studied in this paper. We not only compared the advantages and disadvantages of deep learning models and traditional machine learning methods, but also analyzed the performance of different deep learning models. First, Hela cells injected with different anti-stress drugs were divided into groups for experiment. G3BP, TIA-1 and the nucleus were labeled, respectively. The images were obtained using a single-photon microscope. Then, we distinguished the images of Hela cells treated with different drugs through visual observation, traditional machine learning (LBP/Gabor+SVM) and deep learning algorithms (VGGNet, GoogLeNet, ResNext and DenseNet), respectively. Experimental results showed that compared with visual observation, traditional machine learning and deep learning algorithms had better objectivity. Furthermore, deep learning models all had good classification performance. The highest average correct recognition rate was 92.97%, while that of the traditional method was only 80.93%. Therefore, drug screening methods based on deep learning could assist in screening the optimal treatment drugs, which help clinicians choose appropriate therapy.

Among the biometric identification methods, fingerprint identification is one of the most widely researched and applied biometric identification technologies. However, the traditional fingerprint identification system is vulnerable to attacks with the use of fake fingerprints, causing security problems. At the same time, when the skin of the finger is worn, wet, stained the efficiency of fingerprint identification will suffer. Optical Coherence Tomography is a non-invasive high resolution imaging technology that can image the subcutaneous depth of 1mm. Therefore, OCT can be used to obtain fingerprints inside the finger to effectively solve the security problem of fingerprint recognition, and at the same time solve the problem of the reduction in the recognition performance when the finger epidermis is damaged by external factors. In this research, OCT technology is used to collect the data of the three-dimensional structure of the fingertip by the aid of the deep learning U-net, SIFT and FLANN algorithm to ensure the reconstruction and recognition of internal fingerprints. The results show that U-net can extract the contour of the subcutaneous papilla layer and reconstruct the 2D internal fingerprint. Then we use Sift algorithm to match and splice the feature points of the internal fingerprints collected by multiple overlapping and establish a large area of internal finger template library. Finally, the FLANN algorithm library is used to extract the minutiae of the tested internal fingerprint and match the fingerprint template to achieve identity recognition. Compared with the traditional algorithm, this method is difficult to imitate and has high security.

Direct laser writing technology has potential applications in the fabrication of micro and nanostructures such as photonic crystals and photonic chips. However, current single-channel direct laser writing systems are mainly limited to low-flux systems, which have disadvantages such as low direct writing efficiency and slow writing speed. To overcome the limitations, we proposed a method based on screen division multiplexing of the spatial light modulator to parallelly fabricate the nanostructures. The spatial light modulator is divided into two parts to achieve a single column of 20 beams array. After optimizing the uniformity of the 20-beam, a 20-channel high-throughput parallel laser direct writing is thus achieved. This scheme directly writes repetitive patterns by an order of magnitude faster than single-beam laser direct writing, which greatly improves the speed of laser direct writing and has important applications in the direct writing of large-area repetitive devices.

Lateral Shearing Interferometer (LSI), as a kind of self-interference technology, can achieve high-precision wavefront sensing and phase imaging. Quadriwave Lateral Shearing Interferometry (QWLSI) divides the wavefront into four transverse dislocated beams by a checkerboard phase grating. The lateral-shearing interferogram of the four waves occurs on the image plane, and then the test wavefront is reconstructed. The reconstruction precision is determined by the shear ratio, thus the variable shear ratio can meet the requirement of the different measurement accuracy. Here we proposed variable-ratio lateral-shearing interferometry with a vortex-splitting grating. Different from the checkerboard grating, topological charge is first encoded into grating and is then optimized to obtain two shear ratios in the same interference setup. The proposed variable-ratio lateral-shearing setup including of only an axial motion device is robust, effective and variable precision for wavefront sensing.

Terahertz waves are increasingly used in fields such as information and communication technology, homeland security, and biomedical engineering. Optical Coherence Tomography (OCT) is a non-invasive, high-resolution imaging technique that can image within a depth of 1mm under the skin, and it has the characteristics of fast imaging speed and high detection sensitivity. Using OCT technology to study human skin, it was found that the human skin sweat ducts are helical structures. When the sweat ducts of the helical structure are filled with sweat composed of conductive electrolytes, combined with the morphological and dielectric properties of the skin, the sweat ducts can act as low Q-factor helical antennas and have electromagnetic effects in the Sub-Terahertz band. In this study, based on the morphological structure of sweat ducts in the skin, we established a basic sweat duct equivalent model, which consists of spiral sweat ducts and three skin layers (stratum corneum, epidermis, and dermis). In this work, we investigate the frequency points of the stronger radiation of the sweat duct model at different frequencies and compare the effects of the turning direction of the helical sweat duct and changing the length of the sweat duct on its radiation variation at specific frequencies. The results show that there are significant differences in the magnitude and direction of planar radiation for different lengths of sweat ducts, and the differences in the turning direction of the helical sweat ducts also affect the angle of sweat duct radiation. The research on the electromagnetic radiation characteristics of sweat tubes in this study is of great guidance to the IC design research of human skin sweat tubes.

Interferometry technology has a wide range of applications because of high accuracy and sensitivity, the core of which is the processing of interference fringe pattern. The interference fringes with quadratic phase are very common in interferometry measurement, which means that any sophisticated interference fringes can be decomposed or approximatively decomposed by them. Newton’s rings are typical interference fringes with quadratic phase, the physical parameters such as curvature radius and position of ring’s center are included in the pattern. The parameter estimation algorithm of Newton’s rings based on FRFT/DCFT needs only one pattern to realize the estimation through the method of signal processing with advantages of easy operation, high accuracy, high speed and strong anti-noise performance, for reason that the Newton’s ring is actually a two-dimension Chirp signal.

The intensity and frequency properties of laser multiple optical feedback have been investigated. The multiple optical feedback is realized with a high reflectivity feedback mirror in the misalignment external cavity. Experimental results show that the laser intensity is modulated by the variation of feedback cavity length, when the feedback mirror is drove by PZT. In most cases, the modulation depth of the multiple feedback fringes is obviously different. And its frequency analysis results seem like the noise signals. Particularly, at certain misalignment angle of feedback mirror, the envelope of feedback fringes is cosine-like and the modulation depth of the multiple feedback fringes is almost equal. The spectral analysis shows that the fringes density of multiple feedback is increased evidently than that of conventional weak feedback. The resolution of this fringe is upto nanometer level which can be calculated by the spectral analysis result. This high resolution cosine-like fringe of multiple feedback is very useful for high precision sensing applications.

Bioaerosol aerosols originate from a biological source or a biologically active composition in the air everywhere, even in the presence of the ocean and polar regions. Bioaerosols are essential for research in many fields, such as public health safety, botany, and biological warfare. Laser-induced fluorescence technology is a method of using lasers to irradiate a medium so that the electrons in the medium that are originally in equilibrium absorb the photon energy of a specific wavelength and transition to different vibrational energy levels in the excited state, thereby emitting fluorescence of different wavelengths. The wavelength of fluorescence is always longer than the excitation wavelength. In this paper, a bioaerosol detection lidar is developed based on laser-induced fluorescence technology, which can perform fluorescence detection of biological substances at a certain distance, providing a certain basis for real-time detection of bioaerosols. The bioaerosol detection lidar developed in this study provides two laser wavelengths of 266 nm and 355 nm as excitation wavelengths for the detection of two fluorescent substances, tryptophan and riboflavin, contained in bioaerosols. In an outdoor environment, the lidar developed this time was used to verify the detection of tryptophan and riboflavin at different detection distances (30 m, 360 m, 1374 m). After analyzing the detection results, it is concluded that lidar can effectively detect two fluorescent substances, riboflavin and tryptophan, at 30 m, 360 m, and 1374 m.

In this paper, a dual-wavelength square pulses fiber laser with tunable pulse width based on nonlinear polarization rotation and nonlinear effect was studied. The fiber laser containing a 1050-m highly nonlinear fiber operated at central wavelengths of 1533 nm and 1569 nm and the repetition rate was 194.7 kHz. While the polarization state of the laser was unchanged, the pump power was increased from 100 mW to 300 mW, and the pulse width was extended from 163.6 ns to 558.2 ns. In this process, the maximum energy of a single pulse was 8.57 nJ. The simple, compact square pulse dual wavelength fiber laser with tunable pulse width can meet great potential for applications.

Plasmonic nanolasers have been demonstrated in multiple structures, among which semidconductor-metal (SM) plasmonic nanowire laser has simple structure and is suitable for electric pumping. A typical SM plasmonic nanowire laser consists of a high-quality perovskite nanowire laying on the ultra-flat single-crystal silver film. Due to the intrinsic ohmic loss of metal and high radiation loss of nanowire facets, SM plasmonic nanowire laser has features of low quality factor and high threshold. Here, we report a series of designs for improving the quality factor of the plasmonic nanowire microcavities. First, based on the principle of distributed Bragg reflector (DBR), we design 4 forms of structure to enhance the reflectivity of the microcavity nanowire facets. Our simulation results show that one of the designs, dielectric/air DBR at the end of nanowire, owns largest reflectivity. Then the dielectric/air DBR is applied to the plasmonic nanowire laser microcavity. The simulation results indicate that the quality factor of microcavity is improved by more than 75%. This design is easy to implement in the semiconductor process and is able to be applied in the high Q-factor semiconductor-metal (SM) plasmonic nanowire lasers in the near future.

Micro-LED will probably become the next epochal display technology, which has combined the advantages of liquid crystal display (LCD) and organic light-emitting diode (OLED). Its self-luminous characteristic will greatly compress the volume of the projection optical engine into truly pico-projection level. However, the relevant design and research are still insufficient. In this paper, we design a four-piece sphere lens group with a 5 mm focal length for micro-LED pico-projection, and then a simulation model of self-luminous projection optical engine is built for demonstration. The total length of the projection lens group is only 8.2mm, the modulation transfer function (MTF) is higher than 0.5@66lp/mm, and the distortion is below 1%. The irradiance distribution shows that the light efficiency is 44.9 % and the uniformity reaches 81.3% when the light divergence angle of micro-LEDs is set to 30°. Then, we explore the influence on light efficiency with different light source divergence angles and determine the optimal range of divergence angles. Finally, a R/G/B integrated micro-LED source with blue light and the above red/green quantum-dot color conversion (QDCC) layer is built, proving the feasibility of a full-color pico-projection optical engine with a single-integrated micro-LED chip.

Laser intersatellite link (LISL) offers a large bandwidth, low power loss and high reliability transmission scheme to the satellite communication. With the rise of commercial applications of giant constellations, the LISL technology could be used to build the free-space backbone network to deliver the information all over the world. However, the operational scheme on the new frequency-carrier also brings new issues. The transmission performance is highly dependent on the channel quality, i.e., the laser channel for our case. In this paper, we build up the theoretical model of the transmission channel for the LISL system, considering the sun outage, the doppler frequency shift and the platform vibration as the major noise sources for the free-space laser communication system. The numerical simulation is carried out to quantify the detail impacts from these sources and to define the operational region of the QPSK transmission system. According to our calculations, the large elevation angle, the low frequency shift and the less vibration could improve the transmission performance.

Endometrial carcinoma is an epithelial malignant tumor o the endometrium. At present, the conventional methods for endometrial carcinoma detection are cytologial smear and hysteroscopic endometrial biopsy. The hysteroscopic biopsy is a minimally invasive diagnostic and treatment technique in gynecology. However, it can only obtain the lesion of upper mucosa of the uterus by hysteroscopic endometrial biopsy, but cannot detect the infiltration depth of the lesions. Photoacoustic imagining is an imagining technique combining optical and ultrasound. It has both the high resolution of optical imaging and the deep detection depth of ultrasonic imaging. In our study, hysteroscopy-based photoacoustic imaging techniques were proposed to discuss the effect of pigeon intracavitary imaging. The results show that the detectable depth reaches 2.5 cm in our ultrasonic probe with hysteroscopy in vitro. And the longitudinal resolution is 0.5mm. So the system can effectively detect subcutaneous lesions in the cavity. The system is expected to play an important role in the early diagnosis and treatment monitoring of the uterine lesions.

Malignant tumor is a serious threat to human health. With the development of medical technology, a variety of treatment methods appear in clinic. As a non-invasive treatment, laser photothermal therapy is a treatment that kills cancer cells by converting light energy into heat energy through laser irradiation. Its advantage is protecting normal tissue while destroying cancerous tissue. However, it’s still not clear that the effect of heat generated by laser on tissue and temperature changes during photothermal treatment process. Optical coherence tomography (OCT) is a non-contract, real-time optical imaging technology. OCT has been widely used in clinical treatment and scientific research based on fast imaging speed and high detection sensitivity. In our study, breast cancer of mice was chosen as the research object. Combined infrared thermography and OCT were applied to monitor the dynamic changes of tumor tissue. The effect of photothermal from OCT image and temperature were obtained and analyzed. Specifically, we investigated the structural change characteristics and temperature distribution of tumor tissue with increasing laser power. And then, the temperature change of tumors of different sizes at power of 3W were further analyzed. The results show that combined with OCT images and temperature can be well used to guide the photothermal treatment process. It can serve as a basis for the method with safely, consistently and effectively.

Spatial period is an important characteristic parameter in the design and fabrication of continuous phase plate (CPP). The smaller the minimum spatial period, the more freedom of CPP design and the more difficult of CPP manufacture. The minimum spatial period of continuous phase plate determines removal function size of tool in high-precision machining of continuous phase plate. Based on chemical reaction, atmospheric pressure plasma processing (APPP) is a non-contact and high efficiency material removal method. The removal function of APPP is nonlinear with dwell time because of chemical reaction rate affected by temperature. The dwell-time algorithm of variable removal function was proposed in order to solve the nonlinear removal function. APPP for fabrication of continuous phase plate with small spatial period is introduced in this paper. Finally, APPP with variable removal function dwell time algorithm was used to fabrication a continuous phase plate with spatial period of 8mm, surface peak-valley (PV) more than 790nm, wavefront gradient root-mean-square (RMS) of 1.07um/cm. The results show that residual surface error between designed surface and measured surface root-mean-square (RMS) is down to 50 nm. The variable removal function in APPP for fabrication of continuous phase plate with small spatial period is validated.

The mainstream technology used in commercial glucose sensors is enzymatic electrochemical sensing. Although the use of enzymatic electrodes can specifically detect glucose, this sensor has many deficiencies such as large environmental impacts, complex enzyme-modification processes and relatively high cost. Constructing well-designed metal nanostructures can excite environment-dependent surface plasmon resonance (SPR) and generate hot electrons. By monitoring the central wavelength shift of SPR and collecting the photocurrent generated from the hot electrons, label-free, enzyme-free, optical and photoelectrochemical (PEC) dual-mode sensing of glucose can be realized. Here, we combine magnetron sputtering, thermal treatment, nanosphere lithography, electron beam evaporation and lift-off processes to fabricate hexagonally-arranged gold nanohole arrays (Au NHAs) with adjustable diameters on aluminum (Al)/titanium dioxide (TiO₂) film substrates, and constructed an enzyme-free glucose sensor based on the Al/TiO₂/Au NHAs structure. The sensor is demonstrated to work in both optical sensing and PEC sensing modes. For optical sensing mode, the shift of the SPR peak corresponding to the glucose concentration range of 0–10 mM is observed, with an optical sensing sensitivity of 857 nm/RIU. For PEC sensing mode, the sensor at zero bias shows a linear range of 1 µM– 10 mM for glucose detection under simulated one-sun illumination, along with the detection of limit down to 1 µM and the photocurrent sensing sensitivity of 0.53×logC µA μM^-1 cm^-2 (where C is the molar concentration of glucose). Furthermore, the as-prepared glucose sensor also shows good stability and specific selection for glucose detection.

Since the human body has its own unique biological characteristics, such as fingerprints, faces, voices, etc., the biological characteristics of the human body are widely used as a key for image or information encryption to improve the security of the system. However, the biological characteristics of the human body are abused, resulting in reduced safety. In addition, the double random phase template is widely used as the key in optical image encryption technology. However, the linear nature of the double random phase template is vulnerable to attack. Therefore, there is an urgent need to develop a new type of key with high security and not easy to be attacked. In this article, we propose a three-dimensional skin thickness key based on fingerprint guidance. The key generation algorithm includes three steps. First, the convolutional neural network is used to segment the upper and lower boundaries of the epidermal layer in optical coherence tomography (OCT) images of the fingertip skin cross-section, and the deep learning algorithm is used to extract the maximum intensity projection (MIP) image of the internal fingerprint at the fingertip skin epidermis-dermis junction (DEJ). Secondly, by locating some areas in the MIP, the thickness of the upper and lower borders of the skin of part of the fingertips is calculated and converted into a thickness map. Finally, based on the characteristics of the internal fingerprint, the thickness map is selected as the key to encrypt the optical image. The experimental results show that the thickness of the skin of each person's fingertips is different under normal conditions, and the thickness of the skin can be encrypted as important biometric information. Numerical simulation verifies the feasibility, security and robustness of the encryption scheme.

The national major scientific research instrument project: “The accurate infrared solar magnetic field measurements system” (AIMS) is under construction. The figure of the primary of the AIMS can be measured using a computer generated hologram (CGH) test during the polishing process, however, a distortion correction procedure is needed to mapping the coordinates of the mirror and the pixels of fringes due to the large distortion exists in the CGH test configuration, and the mapping relationship need to be re-calibrated after the primary mirror was reassembled, which makes the test process cumbersome. In this paper, a sub-aperture stitching equipment was established, which uses a two\dimensional guide that can move a 450mm reference flat mirror to any position that can cover the aperture of the primary mirror. The surface shape requirement of the 450 mm flat mirror was given by Monte-Carlo analysis and further the figure was tested by using Ritchey-Common technique. Furthermore, a sub-aperture stitching test system was established and a modified simultaneous fitting algorithm was proposed to stitch the sub-aperture wavefront together, the correctness of the technique was verified by a full aperture figure test experiment. Finally, we applied the developed approach to the site test of figure of the AIMS primary mirror.

When measuring image qualities of large aperture cameras, many factors like people moving around, blowing of air conditioners outlets, thermal convection, etc., will give rise to air turbulence (AT). AT mainly induces non-uniform distribution of air components in the image chain of large aperture camera image quality measurement systems, which will lead to variations of system wavefront errors. Thus, AT will introduce errors to measurement results of traditional image quality evaluation methods. Those errors increase with the camera aperture and are usually time-varying. This paper proposes a method to calibrate AT in real time when measuring image qualities of large aperture cameras. A defocused star point target (DSPT) is added to traditional test targets (TTT). The camera under test can capture images of TTT and DSPT simultaneously. The distance between the effective area of TTT and the DSPT is carefully designed so that the corresponding images do not overlap with each other. We calibrate AT induced wavefront errors by processing the DSPT images with phase retrieval method. Experimental results of AT induced wavefront errors calibrated by the proposed method are presented.

As the hardest substance known in nature, diamond has plenty of excellent characteristics of good chemical stability, high thermal conductivity and high transmittance. Due to its unique physicochemical properties, diamond has shown great application value and prospects in the fields of solid-state power electronics, solid wave gyroscope, quantum communication, and high-precision tools, which make a strict request for the surface quality of diamonds. To this end, people have developed ultra-precision machining methods such as mechanical polishing, chemical mechanical polishing, laser polishing, and ultraviolet-irradiated precision polishing. However, owing to the unique lattice structure and ultra-high hardness of diamond, it is difficult to polish its surface roughness less than one nanometer by conventional methods . Therefore, modificating the physical and chemical properties of the diamond surface through the interaction of light and matter is an extremely promising method to reduce the processing difficulty and improve the fabrication accuracy. In recent years, with the continuous development of light source quality, laser polishing and ultraviolet catalytic polishing based on the interaction between light and diamond have received widespread attention. Laser polishing mainly takes advantage of the diamond graphitization under high-power laser irradiation to achieve the removal of diamond surface materials. While ultraviolet-irradiated precision polishing is based on the theory that ultraviolet light sources with the photon energy greater than bandwidth of diamond can induce photochemical reactions on the diamond surface to achieve diamond surface polishing. This paper introduces the main research progress in the field of diamond laser polishing and ultraviolet-irradiated precision polishing and compares the basic principles and processing devices of these two processing methods. Through the discussion of above problems, the characteristics of two processing methods are summarized, and the consideration on the optimization of diamond ultra-precision polishing methods is proposed accordingly, to further improve the processing accuracy of diamond ultra-precision polishing.

When adaptive optics is applied to target identification, laser high beam quality transmission and other fields, extended object wavefront detection is a technical challenge. And the detection accuracy directly affects the adaptive optics correction effect. To investigate the problem that the focal length of microlens affects the accuracy of extended target wavefront detection. In this paper, a simulation model of extended target wavefront detection based on correlated Hartmann's variable focus was established. The model was based on the commonly used optical system parameters, and it was also established by using the theories of Fresnel diffraction, Newton's imaging equation, the working principle of Shack-Hartmann wavefront detector, and wavefront reconstruction. We analyzed the effect of microlens focal length variation on the wavefront detection accuracy. The relationship curves between the wavefront reconstruction residuals RMS, PV and microlens focal length were obtained. And we further analyzed the intrinsic physical reasons for this relationship.The results show that the variation of the microlens focal length affected the point spread function used in the algorithm.The smaller the focal length, the more accurate the corresponding point spread function calculation results. Therefore, the smaller the calculation error of the subaperture offset, the higher the wavefront detection accuracy.

The Poloidal and Tangential X-ray imaging Crystal Spectrometers (PXCS and TXCS) were developed on Experimental Advanced Superconducting Tokamak (EAST) to provide spatially and temporally resolved plasmas ion temperature (T_i), electron temperature (T_e) and rotation velocity (poloidal- and toroidal-, V_p and V_t) profiles. Each spectrometer consisted of a spherically curved crystal and a CMOS pixelated X-ray Detector. Both spectrometers have recently been upgraded to enhance their measurement capabilities and stabilities. A He-like argon crystal (2d=4.913Å) is deployed on the TXCS and a double-crystal assembly including a He-like argon (2d=4.913Å) crystal and a Ne-like xenon (2d=6.686Å) crystal is deployed on the PXCS. To obtain the optimal spatial resolution, the distance from the crystal to the detector and to the plasma center are modified. Meanwhile, the projection angle of the TXCS sightline to the major radial direction is increased from ~ 22.5º to ~ 29.5ºin order to view the plasma with more tangential component. The XCS server is moved from the EAST tokamak hall to an outside lab to avoid harsh electromagnetic environment and thus enhance stability. Finally, the experimental results from the upgraded XCS systems are presented. New spectral lines of Zinc-like, Copper like and Gallium-like tungsten are identified, which are diffracted by the He-like argon crystal. High-quality He-like argon and Ne-like xenon spectra are observed simultaneously on one detector for measurements of plasmas with wide temperature ranges. Comparison of the Ti- and Vt- profiles measured by TXCS with those measured by charge exchange recombination spectroscopy (CXRS) shows that the results are in well agreement, verifying the reliability of the upgrade of the spectrometers.

In present tokamak experiments, radiative-divertor operation mode, achieved by injecting gaseous impurity in the divertor region, can effectively mitigate the erosion in divertor plates due to the huge heat load from main plasma. Precise measurement of injected impurity emissions is crucial to obtain the steady-state radiative-divertor operation mode. A space-resolved vacuum-ultraviolet (VUV) spectroscopy has been developed to observe impurity emissions of injected impurity from the divertor region on Experimental Advanced Superconducting Tokamak (EAST). However, high-frequency detector is still necessary for the vacuum-ultraviolet (VUV) spectroscopy to measure impurity emissions with sufficient sampling rate, e.g., ≥10kHz. Photomultiplier tube (PMT) is widely used in photon counting systems because of its high gain and low light sensing capability. Therefore, a high-frequency PMT-based detector system is developed for the existing VUV spectroscopy to measure the impurity emissions in EAST. The detector system composed by a Hamamatsu R8486 PMT, a 1MHz amplifier and a 1MHz data acquisition board (DAQ). The PMT has sufficient high quantum efficiency in the wavelength range of 115-320 nm, which satisfies the requirement of the VUV spectroscopy. The PMT is installed inside a vacuum chamber which is connected to the VUV spectrometer. The detector system has been preliminarily tested to verify the capability to measure high-frequency signals. The test results show that the performance of PMT detector satisfies the design requirement.

Performance of portable near-infrared spectrometers is easily affected by various factors such as on-site environment, which results in a certain deviation in the on-site predicted results. Partially least square regression (PLSR), as a multiple linear regression method, has been widely used for the analysis of near-infrared (NIR) spectroscopy. However, due to the nonlinear characteristics of the relationship between spectral data and dependent variables, PLSR can easily lead to model errors. Stability and predictability decreased when PLSR is applied in on-site quick detection. How to reduce the errors caused by various environmental factors in the use of portable near-infrared spectrometers is a key issue in promoting the wide application of rapid detection technology based on near-infrared spectral analysis. In this study, the absorption spectra data of glucose solutions of different concentrations are collected by a portable near-infrared spectrometer. Several nonlinear correction algorithms are applied to study the effect of environmental interference during the measurement process. Firstly, the collected spectra data is preprocessed. Secondly, the data is modeled by nonlinear correction algorithms such as optimized artificial neural network (ANN), support vector regression (SVR), and random forest (RF). The impact of different models is compared with to the results using PLSR. It is found that compared with the PLSR linear method, the ANN, SVR and RF nonlinear correction algorithm can eliminate the interference of environmental factors in different degrees. Therefore, ANN, SVR and RF algorithm can improve the prediction accuracy of the model. This study shows that the use of nonlinear correction algorithm for data modeling of portable near-infrared spectrometers can effectively improve the predictive performance of the model.

A near-infrared spectroscopy system is developed to measure accurately content of grain nutrient. The spectroscopic system mainly consists of near-infrared spectrometer, halogen lamp, stepping motor module, light attenuator, volume weight module. Since the absorbance of grain in NIR range is relatively high, a new type of light attenuator is developed to precisely measure the reference spectra. The method to obtain the transmission spectra is discussed in this study. The control system running on Windows operation system is also developed to acquire spectral data and process the obtained data. The control procedures are presented in detail. The spectroscopic system can automatically complete the measurement by the control system. The results showed that the present design can obtain the transmission spectra of grain effectivly

The quality of the output signal of the laser gyro is closely related to the loss of the high mirror. At present, the research on the total loss of the high-reflection film has been quite perfect. In order to further study the optical properties of the high-reflection film, the total loss of the high-reflection film can be refined into three parts: transmission loss, scattering loss and absorption loss. Starting from the current research situation at home and abroad, this paper mainly introduces three methods, including spectrophotometer method, DF transflectometer and cavity ring-down technique, and discusses the measurement principles of these three methods. The development status and accuracy level of transmittance measurement technology, and the advantages and disadvantages of these three methods are analyzed, and the methods to improve the measurement accuracy and the possible development direction in the future are pointed out. Finally, other common methods of transmittance and reflectance measurement and the corresponding measurement accuracy are introduced.

Automatic detection for specular surfaces is always the crucial problem in the manufacturing process. Dust particles and digs are too similar in shape to discriminate from each other by existing detection method. In this paper, a dig and dust discrimination method for specular surfaces based on multi-view fusion is systematically proposed. Structured light modulation analysis technique is adopted to obtain the distribution of defects and dusts. Then, a white light source and two polarizers whose transmission axis are perpendicular to each other are utilized to obtain dusts purely. Finally, dusts are removed from the modulation image with only defects left. The same process is repeated for several times at different observation angles θ_s. Take the intersection of all the detection results to guarantee as much dusts is removed as possible. Simulation and experimental results verify the effectiveness and accuracy of proposed method.

Silicon nitride (SiN) is an ideal material which is compatible with complementary metal-oxide-semiconductor (CMOS) technology. Its advantages include suitability for high power handing, a large spectral range and low thermo-optic coefficient, etc. A polarization beam splitter (PBS) is one of the significant polarization handling devices for integrated silicon photonic circuits. In this paper, a low insertion loss (IL), broadband and high extinction ratio (ER) PBS with a compact coupling length of 6 μm based on an asymmetrical directional coupler (ADC) was proposed. It consists of a fully-etched silicon (Si) strip waveguide and a silicon nitride (Si3N4) strip waveguide with a vertical gap of 100 nm. By carefully optimizing the parameters, the input transverse magnetic (TM) mode polarization from the Si waveguide will couple to the Si3N4 waveguide due to the phase matching, while the input transverse electric (TE) mode polarization will keep propagating in the silicon waveguide due to the large refractive index difference between the two waveguides. For the TE polarization mode, the simulation results show that the IL is less than 0.23 dB and the ER is higher than 56 dB in the wavelength range of 1300-1900 nm. For the TM polarization mode, the numerical results show that the IL is less than 1 dB and the ER is higher than 12 dB in the wavelength range of 1424-1712 nm. Meanwhile, our design also has high fabrication tolerance and is suitable for production on

Laser communication and distance measurement integration technology is an important development direction of space laser technology, and an important way to realize the future integration of space-earth navigation and communication network. In order to break through higher ranging accuracy, make full use of the space laser link, and realize the integration of high-precision laser communication ranging, this paper analyzes the two ranging methods based on space laser communication link technology: symbol synchronization ranging and carrier phase ranging, proposed a Kalman fusion algorithm to combine these two methods. The technology is modeled, analyzed and simulated. The simulation results show that this method effectively combines the accuracy of symbol synchronization ranging and the high stability of carrier phase ranging. In order to further improve the high dynamic adaptability of the algorithm, the algorithm is analyzed and the corresponding parameters are improved. The results show that the improved algorithm can adapt to the characteristics of space links. The method proposed in this paper makes full use of the carrier characteristics of the space laser link and the communication demodulation technology, and improves the system integration while obtaining higher ranging accuracy, which is of great significance for the design of multifunctional light and small laser terminals.

Body temperature screening and measurement using infrared forehead thermometer (IFT), a non-contact thermometer, is an important method to prevent the spread of COVID-19 at present. However, low accuracy and unreliability of current IFT due to ambient temperature effect prevent it application in most of low-temperature environment. The aim of this study was to measure the body temperature accurately using IFT in low-temperature environment. A novel IFT with broad working temperature range and ambient temperature compensation was designed and fabricated, and the performance was evaluated. Also an ambient temperature compensation method based on Bluetooth module was introduced to improve the accuracy of body temperature measurement for the first time. The experiment results demonstrated that the laboratory indication error and repeatability in test mode of this developed IFT were all below 0.2℃ in ambient temperature range of (3~35) ℃. While the extended uncertainty for laboratory indication error was less than 0.1℃ (k=2). Compared with the contact electronic clinical thermometer, the difference of body temperature was improved within the scope of (-0.3~﹢0.3)℃ in low-temperature measurement environment. All the results showed that the IFT fabricated in this paper is sufficient and competent for body temperature screening and clinical body temperature measurement in most of low-temperature environment

In this work, we used photoacoustic spectroscopy to distinguish the different types of blood including four kinds of true blood and two kinds of fake blood. The peak-to-peak spectra of blood were obtained in the wavelength from 700nm to 1064nm based on the established photoacoustic detection system of blood. To accurately discriminate the different types of blood, back propagation (BP) neural network was used to train the photoacoustic peak-to-peak spectra of training blood with 120 groups, the correct rate of distinguishing blood is 76.7% for 30 groups of test samples. Particle swarm optimization (PSO) algorithm was used to optimize the parameters of BP network. The effects of neurons number in the hidden layer, learning rate factor, inertia weight, two acceleration factors, iteration times and training times on the corret rate and mean square error were all investigated. Under the optimal parameters, the correct rate of BP-PSO algorithm was increased to 93.3%. To further improve the correct rate, the dynamic inertia weight strategy was used. Moreover, a kind of improved dynamic inertia weight strategy function was proposed. The correct rate of the improved dynamic inertia weight strategy function was compared with that of the static inertia weight and two other dynamic inertia weight strategy functions. Under the optimal value of the improved dynamic inertia weight, the correct rate reached 96.7%. Therefore, the BP-PSO algorithm combined with the improved dynamic inertia weight strategy function has a potential value in the photoacoustic discrimination of blood.

Perovskite solar cells have been widely used because of their high photoelectric conversion efficiency. It has been shown that the light-trapping structure can enhance absorption and reduce the additional light energy loss. Therefore, we propose a feasible method to construct pit array texture structures at the top and bottom of the glass respectively, and deposit solar cell materials on the substrate in turn. The primary mechanism of absorption enhancement of three different texture cells is simulated by the finite difference time domain method, and their limit efficiency is calculated and compared with planar devices. The results show that the perovskite solar cell with a double-sided textured structure has better anti-reflection and light capture characteristics. The light absorption is significantly improved in the 300-800 nm wavelength range. Compared with planar perovskite solar cells, the reflection is reduced by about 55% and the ultimate efficiency is increased by more than 8%. The textured structure can be used in various solar cell devices to improve cell performance.