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2025
Volume: 46 Issue 1
26 Article(s)
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Summary and prospect of mechanism position measurement methods for segmented space optics systems
Yuchen LI, Chao QIN, Qichang AN, and Zhenbang XU
Building a large-aperture segmented space optical system is a comprehensive task involving disciplines such as optics, materials science, mechanics, and control theory. In order to achieve observation goals, high requirements have been placed on the motion accuracy of the opto-mechanical structure of space optical systBuilding a large-aperture segmented space optical system is a comprehensive task involving disciplines such as optics, materials science, mechanics, and control theory. In order to achieve observation goals, high requirements have been placed on the motion accuracy of the opto-mechanical structure of space optical systems. Currently, how to effectively measure and correct the misalignment of mechanisms caused by complex environmental loads in space is an important problem that needs to be solved in order to achieve higher positional accuracy in situ. Relying on optical measurement systems to achieve high-precision in situ measurement of space mechanisms is the key to solve this problem. The key technologies and research status of precision optical measurement systems were reviewed from different measurement dimensions, different levels of accuracy, and different measurement principles, and their development trends and application scenarios in space optical systems were described and summarized..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 1 (2025)
Advances in spectral matching techniques for solar simulators
Tingting LI, Yajun PANG, and Jianyang LIU
The solar simulator is an important experimental device that can offer irradiation resembling natural sunlight indoors, which can be used for testing and calibrating products such as photovoltaic modules and photoelectric devices by simulating real sunlight conditions. To assess the performance of products accurately, The solar simulator is an important experimental device that can offer irradiation resembling natural sunlight indoors, which can be used for testing and calibrating products such as photovoltaic modules and photoelectric devices by simulating real sunlight conditions. To assess the performance of products accurately, it is crucial that the solar simulator spectrum and the real solar spectrum match to a great degree. Firstly, an introduction to the application fields and the categorization standards for solar simulators was briefly described. Then, the spectrum matching techniques for solar simulators with various light sources were summarized. According to these different spectrum matching techniques, the structures of typical solar simulators were introduced and their spectral matching performances were compared. Finally, based on the current demand, the development trend of spectrum matching techniques in solar simulators was summarized and analyzed..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 17 (2025)
Design of optical system for dual-band co-aperture heatless gun objective lens
Xinru BAI, Shilei JIANG, Xuhang GONG, Dacheng JIANG, and Jiang FENG
To meet the requirements of integrating day and night in electro-optical sights, lightweight design, and excellent stability, a dual-band co-aperture digital aiming objective lens that was visible and near-infrared was designed, and used a CMOS camera to receive the imaging beam. The optical system was designed for theTo meet the requirements of integrating day and night in electro-optical sights, lightweight design, and excellent stability, a dual-band co-aperture digital aiming objective lens that was visible and near-infrared was designed, and used a CMOS camera to receive the imaging beam. The optical system was designed for the wavelength ranges of 0.4 μm~0.65 μm and 0.7 μm~0.85 μm, with a focal length of 50 mm, an F-number of 1.4, and a total length of 90 mm. The system shows no thermal difference effects in the temperature range of ?40 °C to 50 °C, with distortion in each band less than 0.04%. In the visible light band, the modulation transfer function (MTF) is greater than 0.55 at 100 lp/mm, and in the near-infrared band, the MTF is greater than 0.3 at 100 lp/mm. By optimizing the aberrations caused by the sensitive surface of the system and properly distributing the optical power, the sensitivity of the system to processing tolerances, assembly difficulty, and cost were reduced. The design results show that the system uses spherical mirrors, making it simple in structure, small in size, low in cost, and with good tolerances, which can achieve good imaging quality across the entire operating temperature range, and has a certain engineering application prospect..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 32 (2025)
Design and experimental study of filter wheel mechanism of space coronagraph
Wei GUO, Mingming XU, Jiangpei DOU, Jinning HE, Zihao ZHANG, and Lingyi KONG
In order to realize multi-spectral imaging of space coronagraph of Chinese space station survey optical telescope, a compact filter wheel mechanism was designed to cut the filters with different spectral transmittance into the optical path. Because the space coronagraph needed long-term observation in orbit, the high sIn order to realize multi-spectral imaging of space coronagraph of Chinese space station survey optical telescope, a compact filter wheel mechanism was designed to cut the filters with different spectral transmittance into the optical path. Because the space coronagraph needed long-term observation in orbit, the high stability requirement for the filter wheel mechanism was put forward. A filter wheel based on small modulus worm gear as a mechanical transmission mechanism was designed, which had the features of compact structure, high stiffness, one-way 360° rotation and reverse self-locking function. The precision, stiffness, and mechanical properties of the mechanism were analyzed, and the precision of the filter wheel was tested before and after the vibration test. The test results show that the positioning accuracy of the filter wheel is less than or equal to ±0.5 mm, and the first-order modes of the three directions of mechanism are all greater than 100 Hz. The vibration test analysis results show that the designed stiffness and dynamic performance of the mechanism can meet the requirements of aerospace mechanics environment, which can ensure the multi-spectral imaging under complex spatial conditions..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 41 (2025)
Research on ground scanning scheme of electro-optic payload for loitering missile
Jiajia LI, Lei ZHU, Xuechen ZHAO, Hu LIU, Weiliang YAN, Yan WU, Wei JIANG, Haibo LONG, and Rui HOU
Electro-optic payload technology is one of the core technologies of loitering missiles. A ground scanning scheme for the electro-optic payload with azimuth-pitch structure of loitering missiles was proposed to comprehensively consider the key factors affecting the scanning field of view, such as the parameters of the pElectro-optic payload technology is one of the core technologies of loitering missiles. A ground scanning scheme for the electro-optic payload with azimuth-pitch structure of loitering missiles was proposed to comprehensively consider the key factors affecting the scanning field of view, such as the parameters of the photoelectric sensor, the missile's attitude, and motion information during the process of scanning for ground targets. A mathematical model was established between the flight altitude, velocity, frame angles of electro-optic payload, scanning angular velocity, field of view angle and coverage of scanning field. A seamless ground scanning scheme was derived, the constraints for the seamless scanning scheme was given, and the seamless scanning widths under different flight speeds and scanning angular velocities were calculated. The coverage of the scanning field under different flight and scanning parameters was analyzed by simulation. The results show that the designed ground scanning scheme of electro-optic payload can meet the requirements of no blind area in the scanning field of view, and there is an optimal matching relationship between the flight speed of the loitering missile and the scanning angular velocity of the electro-optic payload..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 49 (2025)
Analysis of variational momentum of zero position based on rear mounted reticle with projected brightness system
Haijin YANG, Zhenzhen BIAN, Xuejun GAO, Zhenlong SI, Fang HAO, Yufen YUAN, Jiang ZHAN, He GAO, and Na LI
Aiming at the variational momentum of the zero position overshoot problem when rear mounted reticle with projected brightness was applied in a certain type of low-light-level (LLL) sight mirror, the zero stability mechanism of this kind of LLL sight mirror was analyzed. The impact test shows that the main reason for thAiming at the variational momentum of the zero position overshoot problem when rear mounted reticle with projected brightness was applied in a certain type of low-light-level (LLL) sight mirror, the zero stability mechanism of this kind of LLL sight mirror was analyzed. The impact test shows that the main reason for the variational momentum of the zero position overshoot is the rotation of the combined prism in the optical system during shooting. The overall size and mounting size tolerances of the combined prism were optimized, the gap between the two sizes was less than 0.02 mm, and the variational momentum of the zero position (Δd) of the LLL sight mirror was less than 0.26 mil, meeting the requirements of Δd≤0.7 mil specified in the system technical specifications. The key points and solutions of variational momentum of the zero position control in design and production of similar scope were given, which provided an effective analysis basis for improving the zero stability of the scope..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 55 (2025)
Injection locking effect based on coupled optoelectronic oscillator
Jingkai ZHANG, Deqi LI, Tianqi ZHAO, Hongbo LOU, Jiawei ZHENG, Xianzhu LIU, and Tianshu WANG
A theoretical model of coupled optoelectronic oscillator (COEO) based on injection locking was proposed. The frequency response of the injection-locked COEO was obtained by viewing the optical fiber loop and the injection-locking effect as two cascaded bandpass filter, and the influence of the injection-locking effect A theoretical model of coupled optoelectronic oscillator (COEO) based on injection locking was proposed. The frequency response of the injection-locked COEO was obtained by viewing the optical fiber loop and the injection-locking effect as two cascaded bandpass filter, and the influence of the injection-locking effect on the output characteristics of the COEO was analyzed. In the experiment, the dynamic output range of the COEO under injection-locked conditions was determined by simulating frequency detuning conditions with the help of a tunable optical delay line. The output signal quality of the COEO under injection-locked conditions was investigated by adjusting the signal generator for different injection signal strengths. Under the conditions of injection signal strength of ?15 dBm, the generated side-mode rejection ratios of microwave signal is 59 dB. The phase noise of the injection-locked COEO at near from the carrier signal is ?124.1 dBc/Hz@10 kHz, the spurious mode suppression ratio is 39.3 dB at far from the carrier signal, and the frequency drift is controlled within 15 mHz. When the injected signal strength is ?12 dBm, the generated side-mode rejection ratios of microwave signal is 66 dB. The phase noise of the COEO at near from the carrier signal is ?117.6 dBc/Hz@10 kHz, the spurious mode suppression ratio is 41.2 dB at far from the carrier signal, and the frequency drift is 10 mHz..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 62 (2025)
Optical structure symmetric imaging spectrometer based on single grating spectroscopy
Jiamei LIU, Changlong CAI, Jiaqi FAN, Haojie YAO, Shijie LI, Jin ZHANG, and Haifeng LIANG
Aiming at the complex structure of imaging spectrometer and the difficulty of correcting spectral line bending, a high-resolution imaging spectrometer based on a single transmission grating was designed and developed. Firstly, the optical splitting model of a single transmission grating was established, and the design Aiming at the complex structure of imaging spectrometer and the difficulty of correcting spectral line bending, a high-resolution imaging spectrometer based on a single transmission grating was designed and developed. Firstly, the optical splitting model of a single transmission grating was established, and the design parameters of the optical splitting system were calculated and determined. Among them, the collimation part and the focusing imaging part of the optical splitting system adopted the symmetry optical structure, which was conducive to the correction of aberrations and reduce the cost of the system. In the design process, the spectral resolution was taken as the main goal, and gradually optimized from the focusing system to the whole spectral splitting system. Finally, a set of optical splitting system with slit width of 11.42 μm, working band of 450 nm~650 nm, spectral resolution of 2 nm, F-number of 2.5, the maximum spectral line bending of 19 μm, and the maximum color distortion of 0.35 μm was designed. According to the design results, the fabrication and assembly of the imaging spectrometer were completed. The experimental results show that the spectral resolution of the system is not less than 2 nm, which meets the design requirements, and proves that the imaging effect of the spectrometer is good..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 71 (2025)
Structural optimization design of LED railway signal lens based on free-form surface
Qing HE, Zhenglin ZHANG, and Yaojun KANG
Color light signal is an important part of China railway signal outdoor equipment, but the signal light source in bad weather conditions due to atmospheric sol scattering and absorption will lead to the inconformity between the output light and the actual identification color of drivers. To ensure that the light sourceColor light signal is an important part of China railway signal outdoor equipment, but the signal light source in bad weather conditions due to atmospheric sol scattering and absorption will lead to the inconformity between the output light and the actual identification color of drivers. To ensure that the light source can transmit the correct traffic signal, on the basis of the existing LED railway signal, an optimal design scheme of signal lens structure based on free-form surface was proposed. The freeform surfaces of the transmission and reflection parts of the lens were iteratively calculated and numerically fitted according to Snell's law. The calculated lens bus was imported into SolidWorks 3D modelling software to complete the 3D lens modelling, and the results of LED lamp beads and lamp beads embedded in the lens were simulated and compared with TracePro optical software. The simulation results show that compared with the direct emission of the LED light source, the maximum of the total luminous flux on the receiving surface of the LED light bead embedded in the free-form lens is increased by nearly 500 times, and the beam dispersion angle of the LED light source is reduced from 90° to 6°. On this basis, the design of the lamp plate for the railway signal field was further developed and compared to the honeycomb lens. The optical analysis and experimental results demonstrate that the free-form lens structure provides better light distribution uniformity than the honeycomb lens. Furthermore, the new LED railway signal meets the requirements of TB/T 2353-2018 "The Luminous Intensity of Railway Signal Light", which can realize the light color of light source to be correctly transmitted to the driver's line of sight after atmospheric sol scattering and absorption, and further ensure the driving safety..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 80 (2025)
Visual fusion perception method under uneven illumination in tunnel of autonomous vehicles
Qinglu MA, Xihong WANG, Lian MA, and Xuefeng DUAN
In order to solve the visual perception problem of unmanned vehicles caused by uneven light in tunnels, an enhancement method based on the fusion of active infrared and visible light was proposed. By supplementing image texture and detail information, the impact of tunnel light fluctuations on unmanned driving was imprIn order to solve the visual perception problem of unmanned vehicles caused by uneven light in tunnels, an enhancement method based on the fusion of active infrared and visible light was proposed. By supplementing image texture and detail information, the impact of tunnel light fluctuations on unmanned driving was improved. Firstly, the image was denoised by pilot filter, and the visual information in the tunnel under different illuminance was enhanced by contrast limit adaptive histogram equalization. Secondly, the enhanced infrared and visible images were decomposed by using the non-subsampling contour wave method. The fusion rules of regional energy adaptive weighted average and convolutional sparse representation were used for low frequency base and detail respectively, and the significance fusion rules were applied to the directional components of high frequency details. Finally, the high and low frequency fusion components were reconstructed. Experimental results show that the average time of CSR-RE algorithm based on convolutional sparse representation and regional energy adaptive weighted average is reduced by 0.05 s compared with deep learning framework (DLF) algorithm. Compared with the fusion method based on sparse representation, the mutual information (MI) value of CSR-RE algorithm is increased by 1.5, and the spatial frequency (SF) value is increased by 0.51 at most. The overall performance of CSR-RE algorithm is better than that of other algorithms..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 89 (2025)
Visual SLAM optimization algorithm based on dynamic object detection
Xubiyue SHANG, Junwei TIAN, Xingang WANG, Yuhan BU, and Wenbo ZHANG
In the actual environment, the localization accuracy of the simultaneous localization and mapping (SLAM) system mounted on the mobile robot is often low due to the influence of dynamic objects, and the camera orientation position will fail when it is serious. On this basis, a RDFP-SLAM algorithm combining you only lookIn the actual environment, the localization accuracy of the simultaneous localization and mapping (SLAM) system mounted on the mobile robot is often low due to the influence of dynamic objects, and the camera orientation position will fail when it is serious. On this basis, a RDFP-SLAM algorithm combining you only look once (YOLO) dynamic object detection network and LK optical flow method was proposed. In the visual odometry thread, the object detection network YOLOv5 was used to detect the dynamic target in the image acquired by the camera, then the LK optical flow method was used to determine the real dynamic feature points in the expected dynamic target detection box and remove them, and the remaining static feature points were involved in pose estimation and mapping. Finally, the experimental test was carried out in the public data set TUM, KITTI and the real dynamic environment. Experimental results show that under the influence of multiple visual sensors and different indoor and outdoor environments, the RDFP-SLAM algorithm still has a significant reduction in time consumption compared with the same type of algorithms, and effectively improves the accuracy of feature extraction in dynamic environment, so that the robustness, real-time performance and positioning results of the system are optimized..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 102 (2025)
Template voting and multi-directional fusion for near-infrared finger vein recognition
Man LI, and Sen LIN
Aiming at the problems of strong local pixel similarity and poor recognition effect in a single direction of finger vein images collected under near-infrared light, a finger vein recognition method based on template voting and multi-directional fusion was proposed. Firstly, the template voting local three pattern (TVTPAiming at the problems of strong local pixel similarity and poor recognition effect in a single direction of finger vein images collected under near-infrared light, a finger vein recognition method based on template voting and multi-directional fusion was proposed. Firstly, the template voting local three pattern (TVTP) was proposed to fully use the information of local multi-neighborhood points and reduce local pixel similarity. Secondly, based on the rich directional feature information contained in finger vein images, the multi-directional coding (MDC) was proposed to acquire directional features with image discernment, strengthen the robustness between different directional features, and solve the problem of poor recognition rate of a single direction. Finally, the block histogram was used for statistical features and collaborative representation (CR) was used to improve the recognition efficiency. The experimental results show that the recognition rate of the proposed method on the SDUMLA dataset, USM dataset, and THU-FVFDT2 dataset reaches 99.32%, 99.73%, and 99.75%, respectively. Compared with other classical and novel algorithms, the proposed method achieves better recognition effects, meets real-time requirements, and has application values..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 112 (2025)
Rapid measurement of sludge sedimentation ratio based on polarization information
Xinqiang WANG, Shan QIN, Xiaobing SUN, Wei XIONG, Song YE, Fangyuan WANG, and Xuanke TONG
Wastewater treatment is an important part to keep water clean in human production and life, and sludge sedimentation ratio is the key index to measure the effectiveness of wastewater treatment. The existing measurement of sludge sedimentation ratio needs to wait for the completion of impurities settling, which is time-Wastewater treatment is an important part to keep water clean in human production and life, and sludge sedimentation ratio is the key index to measure the effectiveness of wastewater treatment. The existing measurement of sludge sedimentation ratio needs to wait for the completion of impurities settling, which is time-consuming and inefficient to detect. In order to achieve real-time, non-contact and low-consumption measurement of sludge sedimentation ratio, the relationship between optical polarization information and sedimentation ratio of homogeneous sludge water samples was studied. The polarization feature parameters were extracted by measuring the polarization image of the mixed solution before sludge sedimentation, the back propagation (BP) neural network was used to train and model the polarization parameters and sedimentation ratio, and the BP neural network prediction model with input layer of I, Q, U, P, θ and hidden layer of 13 nodes, output layer of sludge sedimentation ratio and network topology of "5-13-1" was established. The Levenberg-Marquardt (L-M) algorithm was used for model training, and tansig-purelin was used for the network transfer function. The results show that the average relative error of the prediction model is 4.361%, the average absolute error is 0.008 21, the mean square error was 0.000 14, and the root mean square error was 0.012 13, all of which are within the error tolerance and can be used for rapid prediction of sludge sedimentation ratio..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 121 (2025)
Aircraft takeoff and landing path wind field measurement based on lidar and CFD model
Lin CHEN, Xiaoliang SUN, Yicheng SHENG, Daoming BI, and Jun LIU
The three-dimensional information of wind field in aircraft take-off and landing channels is crucial for aircraft safety, but still lacks an accurate and efficient measurement method. To address this problem, a LiDAR-based wind field measurement method was proposed, which established a computational fluid dynamics (CFDThe three-dimensional information of wind field in aircraft take-off and landing channels is crucial for aircraft safety, but still lacks an accurate and efficient measurement method. To address this problem, a LiDAR-based wind field measurement method was proposed, which established a computational fluid dynamics (CFD) flow field model library covering typical scenarios of aircraft takeoff and landing path, and performed proper orthogonal decomposition (POD) on the model. Then, in the actual measurement application, the radial wind speed at several sampling points along the direction of the laser beam was measured by the wind measurement lidar, and the best matching flow field model was searched in the model library accordingly. The POD coefficients of the best matching model were corrected by the results of radial wind speed measurements, and the modified CFD flow field model was reconstructed. The experimental results show that the proposed method can achieve accurate and efficient measurement of the three-dimensional information of wind field in aircraft take-off and landing channels, and the accuracy of the wind speed measurement is better than 0.8 m·s?1..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 129 (2025)
Hole target detection and location of complex workpiece based on binocular vision
Chunyan ZHANG, Zhifeng ZHOU, Yun SHI, Guoling CHEN, and Wenjie LI
A binocular vision detection and positioning method was proposed to solve the problem of post-processing of hole support residue in metal 3D printing parts. The hole position of the workpiece was detected by the measuring system based on the arc ellipse recognition algorithm. By calculating the pose of the hole positioA binocular vision detection and positioning method was proposed to solve the problem of post-processing of hole support residue in metal 3D printing parts. The hole position of the workpiece was detected by the measuring system based on the arc ellipse recognition algorithm. By calculating the pose of the hole position to be machined in the optical center coordinate system of the main camera in binocular module, and converting the pose to the base coordinate system of the robot arm on machining site, the coordinate information was provided for off-line programming and automatic machining. Firstly, the binocular camera was calibrated and the measurement accuracy of the hardware system was checked. Then, the position ellipse features of the complex workpiece to be processed were extracted, and the parallel pixel acquisition and binocular matching were carried out for left and right image ellipses based on the pole-corrected images. Finally, the coordinates of matching point pairs were calculated according to the multi-view principle, and the spatial ring with coordinate information was output. A calibration target ball measurement verification experiment was carried out for binocular camera module. The results show that the measurement error is less than 0.20 mm. The measurement and positioning experiment of the actual workpiece was carried out. The results show that the maximum error of the system is less than 0.84%, the error of the center space is less than 0.50 mm, and the maximum error of the attitude of the ring is less than 0.5°..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 137 (2025)
Improved double-pass measurement method for detecting right-angle errors of corner cube prisms
Manlin HAN, Sen HAN, Quanying WU, Linghua ZHANG, Yuhang SHEN, Ying YANG, and Jingming GUO
The traditional method for measuring the right-angle error of a corner cube prism involves using the Fizeau interferometric system with a single-pass method. However, this method has some limitations, including the presence of systematic aberrations caused by multiple retro-reflections and errors introduced by adjustinThe traditional method for measuring the right-angle error of a corner cube prism involves using the Fizeau interferometric system with a single-pass method. However, this method has some limitations, including the presence of systematic aberrations caused by multiple retro-reflections and errors introduced by adjusting the tilt of the reference mirror. An improved double-pass method was used to measure the right-angle error of a corner cube prism. This method could match the irregularities of the reference light and the test light, which eliminated the effect of systematic aberration and eliminated the need to adjust the reference mirror. Experiments were carried out using a Fizeau interferometer to measure the same corner cube prism using the traditional method and the improved method. Single-pass measurements result in dihedral angle errors of 0.978 5 μrad, 1.536 8 μrad, and ?0.355 8 μrad, respectively. Double-pass measurements result in dihedral angle errors of 0.638 3 μrad, 1.260 9 μrad, and ?0.311 3 μrad. The experimental results verify that the double-pass measurement method is more accurate than the single-pass measurement method..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 148 (2025)
Defect detection method of photovoltaic panel in bright environment based on linear array InGaAs camera
Han XU, Yunsheng QIAN, Yijun ZHANG, Yizheng LANG, and Yidong HUANG
In bright environments, sunlight can easily drown out the defect information of photoluminescence (PL) phenomenon of photovoltaic panels, so that the inspection equipment cannot directly perceive the defects. To solve this problem, a detection method based on time domain error was proposed, which could effectively reduIn bright environments, sunlight can easily drown out the defect information of photoluminescence (PL) phenomenon of photovoltaic panels, so that the inspection equipment cannot directly perceive the defects. To solve this problem, a detection method based on time domain error was proposed, which could effectively reduce the interference of sunlight in bright environments. In this method, the fast pulse width modulation (PWM) chopping constant current power supply was used to output the high-frequency modulated current signal, the 850 nm light source was driven to output the modulated light to excite the photovoltaic panel, the short-wave linear infrared array InGaAs camera was used to capture the image sequence with modulation characteristics, and the defect information of the photovoltaic panel was extracted from the image sequence by field programmable gate array (FPGA). Experimental results show that the proposed method can effectively detect defect pattern information in the illumination range from 2.9 lx to (12 580±5) lx, and realize the continuous defect detection of photovoltaic panels in bright environments..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 156 (2025)
Precision assembly and testing for imaging detector in photoelectric imaging system
Xiaoxiao WANG, Xingchang ZENG, Zhijie WANG, Yongfeng LI, Yi HUANG, and Shengwei ZHU
The positioning state of the imaging detector assembly has an important influence on the performance of the photoelectric reconnaissance system. The tilt, translation, rotation and position of the detector image plane will bring multi-dimensional errors during the installation and adjustment process, leading to the imaThe positioning state of the imaging detector assembly has an important influence on the performance of the photoelectric reconnaissance system. The tilt, translation, rotation and position of the detector image plane will bring multi-dimensional errors during the installation and adjustment process, leading to the image plane imbalance of the imaging detector in the over-the-horizon observation system, and resulting in image blur and optical axis offset. A set of optical measurement system was designed and built, which adopted the image sharpness evaluation method of gray gradient to automatically judge the installation and adjustment errors of imaging detector. The installation accuracy could reach 0.015 mm, and the qualification judgment of the installation could be given according to the errors of the gray gradient value of the multi-region of interest (ROI) image of the optical measurement system. The optical precision assembly system lays a foundation for the realization of multi-dimensional accurate quantitative assembly of the detector by "mechanical agent"..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 163 (2025)
Optical distortion correction methods for infrared and visible light bombing ballistic theodolites in testing ranges
Guodong YU, Chunyang WANG, Jianghai FENG, Zhongqi LI, Pengyu XU, Peng HAN, Xinze LI, and Feng XU
Optical distortion is a significant factor that impacts the angular measurement accuracy of optical devices. In addressing the issue of optical distortion significantly affecting the testing precision in infrared and visible light bombing ballistic theodolites in shooting ranges, three optical distortion correction metOptical distortion is a significant factor that impacts the angular measurement accuracy of optical devices. In addressing the issue of optical distortion significantly affecting the testing precision in infrared and visible light bombing ballistic theodolites in shooting ranges, three optical distortion correction methods were employed to verify the correction effectiveness: polynomial fitting, multi-surface function fitting, and Kriging interpolation. After verification, it is found that the difference in distortion correction effect of infrared imaging equipment using polynomial fitting method of various orders is not obvious, and the corrected results can be better than 8" after modification. However, there are significant differences among the three models of visible light imaging equipment, and only the fifth-order model can reduce the error to less than 10". When using the multi-surface function fitting method, the smoothing factor has a greater impact on the distortion correction accuracy of infrared and visible light, while the impact of kernel function is not obvious, so the focus should be on the selection of smoothing factor. The optimized parameter vector has a greater impact on the Kriging prediction model, especially when the variogram is a Gaussian function. When the anisotropic characteristics of the distortion vector are not prominent, the advantages of Kriging interpolation are not significant..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 170 (2025)
Fusion of visual calibration and spot detection algorithm for PCB drilling positioning
Duo YANG, Shuchen ZHANG, Xin CHEN, Pengfei YI, and Hongwei WU
To address the issue of multiple calibrations in current printed circuit board (PCB) drilling positioning methods, a novel PCB drilling positioning method that integrated visual calibration and spot detection algorithms was proposed, which could adapt to dynamically changing shooting environments, thereby improving theTo address the issue of multiple calibrations in current printed circuit board (PCB) drilling positioning methods, a novel PCB drilling positioning method that integrated visual calibration and spot detection algorithms was proposed, which could adapt to dynamically changing shooting environments, thereby improving the robustness of PCB drilling positioning. The proposed method was based on Zhang's calibration method, and the camera parameters as well as distortion coefficients were obtained by shooting the calibration board from multiple angles. These parameters were then used to correct the PCB image, and a multi-scale spatial spot detection algorithm was employed to extract the center coordinates of the drilling points in the PCB image. Finally, with the help of camera parameters and image coordinates of PCB drilling points, the three-dimensional spatial coordinates of PCB drilling points were successfully reconstructed, and efficient drilling point positioning was realized. Through the experiment, the positioning accuracy of this method fluctuates around 0.1 mm, with an average positioning error controlled within 0.05 mm~0.07 mm. The results show that this method possesses a certain degree of operational flexibility and robustness, which meets the requirements of PCB mechanical drilling processing..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 178 (2025)
Design of mid-wave infrared metal wire-grid polarizer with sub-wavelength single-layer antireflection film
Peiyao WANG, Huangeng LIU, and Liyong REN
A Si-based gold (Au) wire-grid polarizer was designed for the 3 μm~5 μm mid-wave infrared (MWIR) wavelength range. The introduction of an MgF2 dielectric layer between the Au grid and the Si substrate was proposed to improve the transmittance of transverse magnetic (TM) waves and the extinction ratio (ER) of the wire-gA Si-based gold (Au) wire-grid polarizer was designed for the 3 μm~5 μm mid-wave infrared (MWIR) wavelength range. The introduction of an MgF2 dielectric layer between the Au grid and the Si substrate was proposed to improve the transmittance of transverse magnetic (TM) waves and the extinction ratio (ER) of the wire-grid polarizer. The structural parameters of the Au grid on the Si substrate were optimized using COMSOL simulation software. The results show that the average transmittance of TM waves is 93%, and the average polarized ER is 39.3 dB. In addition, a method of using tungsten (W) as a new metal material to improve the polarization performance of the wire-grid polarizer was proposed. The simulation results show that the average transmittance of TM waves is 92.7%, and the average polarized ER is 64.4 dB. However, the W has higher hardness and higher requirements on the etching process. It is expected to make superior MWIR wire-grid polarizers through advances in process and technologies..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 186 (2025)
Mathematical modeling and evaluation of signal-to-noise ratio for single-photon laser active detection
Yunhang HU, Lingjie WANG, Yang LIU, Lianqiang WANG, and Di ZHOU
Long-range detection using single-photon lidar can increase the farthest detection distance, and due to the complexity of its transmission link, a mathematical model of signal-to-noise ratio for single-photon laser active detection was established. Firstly, the echo signal model of the pulsed laser in the full link of Long-range detection using single-photon lidar can increase the farthest detection distance, and due to the complexity of its transmission link, a mathematical model of signal-to-noise ratio for single-photon laser active detection was established. Firstly, the echo signal model of the pulsed laser in the full link of active detection considering diffraction was established, and the size of the number of signal photons received by the single-photon detector was calculated. Then, the composition of noisy photoelectrons in the active detection process was analyzed, and the number of noisy photoelectrons was quantitatively calculated. Based on the above model, the echo signal-to-noise ratio model under the consideration of the aiming deviation of the optic axis was established. A set of system parameters of a single-photon laser detection system used for theoretical model validation was simulated and analyzed, and the relationship between the laser pulse energy and the size of the echo signal-to-noise ratio was analyzed under the influence of different target detection distances and different aperture sizes of the receiving system. The results were compared with those calculated by the echo signal-to-noise ratio model based on the lidar equation, which proved the simplicity and feasibility of the mathematical model..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 194 (2025)
Interference evaluation of 10.6 μm pulse laser on infrared imaging systems
Hanyu ZHENG, Yunzhe WANG, Tao SUN, and Junfeng SHAO
It is of great military value and practical significance to establish a quantitative law of laser interference to infrared imaging system. The influence of 10.6 μm pulse laser on the target extraction and tracking performance of infrared imaging detectors was deeply analyzed by using the Canny edge extraction algorithmIt is of great military value and practical significance to establish a quantitative law of laser interference to infrared imaging system. The influence of 10.6 μm pulse laser on the target extraction and tracking performance of infrared imaging detectors was deeply analyzed by using the Canny edge extraction algorithm based on contour curvature and cross-correlation template matching algorithm. The normalized correlation between target images and interference images under different target positions and power conditions was used to quantitatively describe the laser interference effect, and an evaluation system with evaluation factors of target distance and laser power was determined to assess the interference level and whether recognition was possible. The results show that the Canny edge extraction algorithm based on contour curvature divides pixels into strong information points, weak information points, and no information points based on curvature, making the algorithm adaptively at the pixel level, and better preserves the detail information of the image. According to the experiments, laser power and target position are the key factors affecting the detection performance of laser interference on infrared imaging guided weapon targets. The evaluation system can balance the importance of target position distance and laser power in the evaluation of laser interference images, and it is found that laser interference will produce many false edge information, which will seriously affect the performance of pattern recognition algorithms. Finally, the evaluation formula is consistent with the experimental results, which can objectively reflect the degree of influence of laser interference on the target extraction and tracking performance of infrared imaging systems..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 202 (2025)
Simulation method for laser polarization transmission characteristics in rainfall environment
Jiayue ZHU, Ming FANG, Yaxin CAI, Qiang FU, and Yansong SONG
Polarized light is easily absorbed and scattered by raindrops when it is transmitted in a rainfall environment near the ground, resulting in severe attenuation and affecting the target detection ability of the optical system. The transmission characteristics of polarized light under different rainfall conditions were sPolarized light is easily absorbed and scattered by raindrops when it is transmitted in a rainfall environment near the ground, resulting in severe attenuation and affecting the target detection ability of the optical system. The transmission characteristics of polarized light under different rainfall conditions were studied to provide a certain basis for polarization detection to overcome the influence of rainfall factors in target detection systems. The Weibull raindrop spectrum was used to characterize the size distribution of raindrops, and the Mie scattering theory was utilized to compute raindrop particle scattering characteristics. The Monte Carlo method was employed to simulate the polarization properties of polarized light after multiple scattering by raindrop particles. Furthermore, the impact of different wavelengths, polarization states, rainfall, and transmission distances on polarization transmission characteristics in rainfall environment was studied. The simulation results show that the polarization degree of the four types of polarized light decreases as rainfall increases, and the transmission distance follows a similar pattern. Under low rainfall conditions, the polarization degree of circularly polarized light exhibits a similar trend to linearly polarized light. However, under high rainfall conditions, circularly polarized light is less susceptible to change compared to linearly polarized light, demonstrating superior polarization retention properties. Furthermore, it is observed that the polarization retention ability of circularly polarized light strengthens with larger wavelengths..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 210 (2025)
All-fiber ytterbium-doped mode-locked picosecond laser based on semiconductor saturable absorber mirror
Kaili CHI, Mei KONG, Qiaochu YANG, Xianzhu LIU, and Tianshu WANG
A ytterbium (Yb)-doped fiber laser based on semiconductor saturable absorber mirror was designed. By adjusting the net dispersion in the cavity with chirped fiber Bragg grating, the output pulse characteristics of the laser were studied when the net dispersion in the cavity was in the negative dispersion region. In theA ytterbium (Yb)-doped fiber laser based on semiconductor saturable absorber mirror was designed. By adjusting the net dispersion in the cavity with chirped fiber Bragg grating, the output pulse characteristics of the laser were studied when the net dispersion in the cavity was in the negative dispersion region. In the experiment, the linear cavity structure with all-polarization maintaining was adopted. When the pump power was 138 mW, the stable self-starting mode-locking was realized. The minimum pulse width of the output pulse is 4.5 ps, the maximum repetition frequency is 46.5 MHz, the central wavelength is 1 063.7 nm, and the spectral width of 3 dB is 1.44 nm. When the pump power is 220 mW and the intracavity filtering bandwidth is 4 nm, the bound solitons with pulse width of 6.24 ps and pulse interval of 46.58 ps can be observed. Finally, the 12-h stability test proves that the laser has good power stability, and can be used as a stable seed source for subsequent applications..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 217 (2025)
Multi-soliton tunable all polarization-maintaining mode-locked figure-nine fiber laser
Tianqi ZHAO, Baoqun LI, Silun DU, Jingkai ZHANG, Mingyu LI, and Tianshu WANG
A self-starting all polarization-maintaining mode-locked figure-nine fiber laser was proposed, and different multi-soliton pulse output could be obtained by adjusting the pump power. When the pump power reached 224 mW, the laser could realize the self-starting of multi-pulse mode-locked state, and the pump power could A self-starting all polarization-maintaining mode-locked figure-nine fiber laser was proposed, and different multi-soliton pulse output could be obtained by adjusting the pump power. When the pump power reached 224 mW, the laser could realize the self-starting of multi-pulse mode-locked state, and the pump power could be reduced to 47 mW under the mode-locked state. At the pump power of 143 mW, 101 mW, 89 mW, 76 mW, 65 mW and 55 mW, the output phenomena of loosely bound state pulses, 2~5 multi-soliton pulses and stable single pulse were observed, respectively. The obtained soliton pulse repetition rate is 8.68 MHz. In the loosely bound state pulses, the signal-to-noise ratio (SNR) is as high as 70.4 dB, the main pulse width is 5.78 ps, and the spacing between two adjacent pulses is 50.04 ps. In the single-pulse state, the SNR is 65.8 dB, the pulse width is 6.17 ps, the average output power is 0.305 mW, and the single pulse energy is 0.035 nJ. In addition, the output power of the laser within 10 h was measured, demonstrating that the structure was highly stable. The experimental results are helpful for further understanding of multi-soliton dynamics, and the laser proposed has the advantages of simple structure, self-starting, good stability, and switchable mode-locked pulse, which is valuable for promoting the application of fiber lasers..
Journal of Applied Optics
- Publication Date: Jan. 15, 2025
- Vol. 46, Issue 1, 224 (2025)
