Journals >Journal of Applied Optics
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2025
Volume: 46 Issue 5
24 Article(s)
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Battlefield application and future prospect of high energy laser weapon
Yishui LIN, Dongxin XU, Qi WU, Yi QU, and Guojun LIU
High energy laser weapon system (HELWS) leverage light-speed strikes, recoil-free damage, and unlimited ammunition capabilities. These attributes are revolutionizing traditional kinetic defense systems and positioning HELWS as a pivotal element in global military competition. This study synthesized global technologicalHigh energy laser weapon system (HELWS) leverage light-speed strikes, recoil-free damage, and unlimited ammunition capabilities. These attributes are revolutionizing traditional kinetic defense systems and positioning HELWS as a pivotal element in global military competition. This study synthesized global technological advancements and practical combat cases to trace the evolution of HELWS from technical validation to battlefield application. Key advancements in high-energy laser technology were analyzed, including China's megawatt-level breakthroughs achieved through the “Shenguang” fusion device and the deployment progress of LW-30/60 tactical laser systems. A comparative analysis of the technology roadmaps of major military powers, such as the U.S., Russia, Germany and Israel, revealed divergent developmental pathways. The operational superiority of HELWS was highlighted in scenarios like short-range defense, anti-missile interception, unmanned aerial vehicle (UAV) suppression, and urban warfare. Furthermore, the disruptive potential of HELWS in space warfare and countering biochemical threats was explored. This work provides a multidimensional theoretical framework for guiding the system development of directed energy weapons and strategic competition in modern warfare..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 945 (2025)
Design of ultra-fine endoscope optical system
Zheng XIANG, Yang XIANG, Xiaohan YUAN, Bowen JIANG, Ning BAI, and Lu YU
The light aperture of the ultra-fine endoscope is fine, at presents most of the ultra-fine endoscopes in the image transmission system use image transmission fiber, which is expensive, and the image transmission has defects such as moire. An ultra-fine endoscope was designed in this paper. The image transmission systemThe light aperture of the ultra-fine endoscope is fine, at presents most of the ultra-fine endoscopes in the image transmission system use image transmission fiber, which is expensive, and the image transmission has defects such as moire. An ultra-fine endoscope was designed in this paper. The image transmission system consists of a number of different short rod lens with a diameter of 0.8 mm and a length of less than 6 mm. The working length of the endoscope is 121 mm, the full field of view is 80°, the radial angle is 0°, and it works in the visible light band. The lens used in the entire endoscopic optical system is a spherical mirror, the modulation transfer function (MTF) of image resolution is greater than 0.1 at 113.5 lp·mm?1, which has a higher resolution than the endoscope with the same diameter image transmission fiber (082F1000-7.0), the diffraction limit could be reached, the depth of field covers the full working range, and all kinds of aberrations are optimized. After the prototype assembly test, the image is clear and the resolution could reach the design index. By using rod lens instead of image transmission fiber, this design provides a feasible solution to solve the problem of moire pattern and high cost when using image transmission fiber for ultra-fine endoscope..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 958 (2025)
Design of optical system for 50x zoom security lens
Shuo ZHAN and Bo LI
To meet the growing demands for high-performance zoom optical lenses in large-area surveillance and high-definition imaging within the security market, a smooth zoom optical system with a focal length range of 10mm to 500 mm was designed. The system employed a mechanical positive compensation method, where optimal initTo meet the growing demands for high-performance zoom optical lenses in large-area surveillance and high-definition imaging within the security market, a smooth zoom optical system with a focal length range of 10mm to 500 mm was designed. The system employed a mechanical positive compensation method, where optimal initial structural parameters were determined through parameter setting and optimization. A moving aperture was implemented to maintain a constant F-number throughout the zoom range. Additionally, aspherical lenses were introduced to effectively correct positional and axial chromatic aberrations, thereby enhancing imaging performance. The optical system consists of 13 spherical lenses and 2 aspherical lenses, with a total length of 375.6 mm. The modulation transfer function (MTF) remains above 0.35 at 104 lp/mm across the entire zoom range. During the design process, motion curves for the zoom and compensation groups were plotted, demonstrating smooth, breakpoint-free transitions, which could validate the system's reliability and stability. Final analysis results indicate that the proposed system meets the practical large-area surveillance requirements and provides valuable references for the design of high-zoom-ratio optical systems..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 966 (2025)
Infrared radiation characteristics of hypersonic cruise missile scarfskin
Yunsong FENG, Yuanxin SHANG, Jun ZHANG, Wei JIN, and Changqi ZHOU
The hypersonic cruise missile undergoes aerodynamic heating, and the scarfskin has a high temperature, generating strong infrared radiation. In order to detect and warn hypersonic cruise missile effectively, it is important to study the spatial distribution characteristics of infrared radiation of hypersonic cruise misThe hypersonic cruise missile undergoes aerodynamic heating, and the scarfskin has a high temperature, generating strong infrared radiation. In order to detect and warn hypersonic cruise missile effectively, it is important to study the spatial distribution characteristics of infrared radiation of hypersonic cruise missile. Firstly, taking X-51A hypersonic cruise missile as the research object, the geometric model of hypersonic cruise missile was established by using software SpaceClaim. Secondly, based on the basic conservation law of hydrodynamics, Fluent software was used to numerically simulate the hypersonic cruise missile's outflow field, and the distribution data such as the missile scarfskin temperature and the pressure around the flow field were obtained. Finally, Monte Carlo method was used to simulate the process of radiation transfer, and the space distribution of middle and far infrared intensity of X-51A aircraft under typical flight conditions was obtained. The results show that the temperature at the head and front section of the inlet of hypersonic cruise missiles is relatively high. At flight speeds of 5 Ma and 6 Ma, the maximum temperature of the skin reaches 1177 .304 K and 1654 .08 K, respectively. As the flight speed increases, the proportion of infrared radiation intensity in the skin increases. In the direction of α=78.75°, the infrared radiation intensity of the skin reaches its strongest. For 5 Ma, the infrared radiation intensity in the middle and far reaches 1.66×104 W/sr and 6.0×103 W/sr, respectively. However, in the head-on or tail direction, the infrared radiation intensity is weaker..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 974 (2025)
Defocusing and compensation analysis of security lens under temperature load
Zhanshan SI, Guangfeng SHI, Ya TANG, Hongsong HAI, and Qing ZHANG
In order to reduce costs and shorten the cycle, it is necessary to carry out heat-free design of security lenses in the design stage. Based on the OpticStudio STAR module as an interface tool between finite element analysis and optical analysis, the optical-mechanical thermal integration analysis of a security lens witIn order to reduce costs and shorten the cycle, it is necessary to carry out heat-free design of security lenses in the design stage. Based on the OpticStudio STAR module as an interface tool between finite element analysis and optical analysis, the optical-mechanical thermal integration analysis of a security lens with an aperture of 1.6～1.3 was performed.The finite element model was established in UG and imported into Ansys. The thermal stress analysis was carried out with the highest and lowest temperatures within the normal operating temperature range of the lens as the load, and the surface profile data and related thermal stress data of the lens were obtained. The profile data were merged into Zemax using STAR module for optical defocus simulation. Through the structure-optical-structure iterative design, the finished lens which could meet the requirements at ?40℃～80℃ image quality was designed. Finally, the imaging stability of the lens in the extreme temperature environment and the accuracy of the optical, mechanical and thermal integrated analysis were verified by the lens defocus measurement at high and low temperatures..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 981 (2025)
Comparative on dynamic performance of double-moving mirror translational interferometer and double-moving arm rotary interferometer
Wanjie REN, Chongchong MAO, Jianquan ZHAO, Jianghao ZHANG, and Xun SUN
Although both double-moving-mirror translation interferometers and double-arm rotary interferometers can effectively mitigate the influence of mirror tilt, existing studies have failed to clarify their differential characteristics, leading to frequent performance misjudgment and selection errors in high-precision scenaAlthough both double-moving-mirror translation interferometers and double-arm rotary interferometers can effectively mitigate the influence of mirror tilt, existing studies have failed to clarify their differential characteristics, leading to frequent performance misjudgment and selection errors in high-precision scenarios. This study reveals the differences between the two configurations through comparative analysis. Two functionally and dimensionally analogous interferometers were designed, and the size of translation interferometer was 443.546 mm×243.773 mm, while that of rotary interferometer was 387.546 mm×300 mm. The interference ranges under mirror tilt conditions were simulated. Results indicate that the tilt angle of the moving mirror in the translation interferometer negatively correlates with the modulation depth. In contrast, the rotary interferometer can compensate for modulation depth reduction by extending reflector dimensions. Critical installation error thresholds were derived. For the translation interferometer, the permissible moving mirror tilt angle was
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 988 (2025)
Miniature missile-borne continuous zoom television camera
Bo ZHANG, Yu ZHOU, Dan HU, Weijun CHANG, Zijian YANG, Yue YU, and Zhi ZHANG
A miniature continuous zoom TV camera was developed to meet the detection and recognition requirements of small cruise-mounted platforms. The 5× continuous zoom optical system was designed and optimized by using CODE V. Its imaging performance was evaluated from multiple dimensions, and its detection and recognitiA miniature continuous zoom TV camera was developed to meet the detection and recognition requirements of small cruise-mounted platforms. The 5× continuous zoom optical system was designed and optimized by using CODE V. Its imaging performance was evaluated from multiple dimensions, and its detection and recognition distance was simulated and verified by experiments. The physical weight of the prototype was 290 g, and the impact vibration test was carried out on it. The test results show that, after 100 g and 8 ms half-sine wave impact, the whole optical axis consistency of miniature missile-borne continuous zoom TV camera is better than 0.15 mrad..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 996 (2025)
Focusing simulation of rotating ellipsoidal mirror based on X-ray optical tracing
Ziwen HUANG, Lei YANG, Shuai ZHAO, Yu YANG, Lei ZHANG, and Keyi WANG
Rotating ellipsoidal mirror is an ideal reflective X-ray focusing device. An X-ray optical tracing method based on Matlab to realize the focusing simulation of the ellipsoidal mirror was proposed. The factors affecting the focusing effect of the ellipsoid mirror were summarized, and the X-ray optical tracing model was Rotating ellipsoidal mirror is an ideal reflective X-ray focusing device. An X-ray optical tracing method based on Matlab to realize the focusing simulation of the ellipsoidal mirror was proposed. The factors affecting the focusing effect of the ellipsoid mirror were summarized, and the X-ray optical tracing model was established. The focusing simulation of two groups of small-diameter ellipsoidal mirrors with a length of 50 mm was carried out at the energy of 8 keV, and the focusing characteristic parameters such as the focal spot size and average reflectivity were analyzed. At the same time, the annular spot under defocus was simulated. The influence of the surface height error and surface roughness on the focusing effect of the ellipsoidal mirror was discussed. The light source intensity distribution information was introduced, and the focusing spots of the average distribution and Gaussian distribution light sources were simulated, respectively, under the condition of surface light source with a diameter of 7 μm. This simulation method supports the independent setting of the ellipsoidal mirror size, surface reflectivity, surface error, light source characteristics and other information. It is both scientific and flexible, and can be used as a convenient tool for intuitively studying the focusing spot and focusing characteristics of the ellipsoidal mirror..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1003 (2025)
Image dehazing algorithm and FPGA implementation via improved rank-one prior
Haofeng HU, Zihan WANG, Longchao WEI, and Xiaobo LI
The image dehazing algorithm restores low-quality images captured in hazy environments to clear images. However, with the increase in image resolution and algorithm complexity, it is challenging to ensure the real-time performance of the algorithm in practical applications. To address this issue, this paper studies andThe image dehazing algorithm restores low-quality images captured in hazy environments to clear images. However, with the increase in image resolution and algorithm complexity, it is challenging to ensure the real-time performance of the algorithm in practical applications. To address this issue, this paper studies and improves a low-complexity ROP (rank-one prior) algorithm and enhances its execution efficiency through an FPGA（field programmable gate array） hardware platform. Firstly, leveraging the parallel processing advantages of FPGA, the algorithm incorporates spatial correlation and dark channel prior constraints to eliminate interference from close-range and high-brightness areas. By optimizing the scattering rate map estimation method, the improved algorithm resolves the artifacts present in images restored by the original ROP algorithm while reducing hardware resource consumption. Finally, the clear image is obtained by solving the estimated ambient light value and scattering rate map. Experimental results demonstrate that the improved algorithm enhances the visual quality of images in scattering scenes such as fog and underwater environments. The restored images exhibit more realistic colors and more details. Implementing this algorithm on the ZYNQ7020 development board (utilizing 21K LUT and 28.9% BRAM resources) processes 1080p images in 54 ms, meeting real-time processing requirements. This has broad applications in fields like autonomous driving and deep-sea exploration..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1011 (2025)
Adaptive detection methods for fuzzy underwater objects
Zhaolong LIU, Hongwu YUAN and Qian YU
Underwater environments usually suffer from issues such as light attenuation, color distortion, complex background interference, diverse target scales, and blurred target features. This paper addresses challenges related to diverse target scales and difficulties in feature localization by proposing an improved underwatUnderwater environments usually suffer from issues such as light attenuation, color distortion, complex background interference, diverse target scales, and blurred target features. This paper addresses challenges related to diverse target scales and difficulties in feature localization by proposing an improved underwater target detection algorithm based on Faster R-CNN ((sg_Faster R-CNN). Firstly, we introduced switchable atrous convolution in feature extraction to address the problem of feature loss due to the absence of global contextual information during feature extraction. Secondly, we used a recursive feature pyramid to enable multiple interactions between high-level and low-level features, enhancing the capability of model to detect small underwater targets and complex-shaped objects. Lastly, we introduced a proposal network based on guided anchor boxes, which could dynamically generate anchors that were sparser and shape-adaptive based on the image's semantic features, significantly improving the accuracy and localization ability of the model for underwater target detection. Experiments demonstrate that the improved algorithm achieves a 5.7% increase in mAP (mean average precision) on the DUO underwater dataset and also performs well on the general-purpose object detection dataset VOC..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1024 (2025)
Enhancement of underwater images based on color compensation and color line model
Xiuman LIANG, Zhigang ZHAO, Zhendong LIU, Haifeng YU, and Xinzhe YAO
Aiming to address the issues of color distortion and haziness in underwater images caused by underwater light attenuation and suspended particles, a color compensation and color line model-based underwater image enhancement algorithm was proposed. Firstly, by improving the color compensation algorithm to assess and comAiming to address the issues of color distortion and haziness in underwater images caused by underwater light attenuation and suspended particles, a color compensation and color line model-based underwater image enhancement algorithm was proposed. Firstly, by improving the color compensation algorithm to assess and compensate for the attenuation channels in the image, the degree of color deviation was reduced and the fitting effect of the color line was improved. Secondly, by combining information entropy evaluation metrics and iterative threshold strategies, image background separation was achieved to avoid the influence of bright foreground objects, thereby enhancing the accuracy of background light estimation. Subsequently, an accelerated convex optimization algorithm was constructed using the color line and background light vectors to accurately estimate the transmittance, thus improving the image dehazing effect. Finally, normalization of the color channels could result in haze-free images without color deviation. The enhanced images could achieve an average peak signal-to-noise ratio (PSNR) of 25.36 dB, underwater color image quality evaluation (UCIQE) of 0.64, underwater image quality measure (UIQM) of 5.02, and color cast factor K of 0.02. Experimental results demonstrate that compared to other algorithms, this method can more effectively address color distortion and haziness in underwater images..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1034 (2025)
Vehicle-mounted infrared target detection based on improved YOLOv5 model
Xinqi YANG, Yang LIU, Xueqiong BAI, Haojiao LIU, and Yazhou CHEN
To address the issue of low detection accuracy in vehicle-mounted infrared target detection algorithms, caused by the limited features and low contrast of small targets, this paper proposed the FE-YOLOv5s vehicle-mounted infrared target detection model. Firstly, the PPA module was integrated into the backbone network tTo address the issue of low detection accuracy in vehicle-mounted infrared target detection algorithms, caused by the limited features and low contrast of small targets, this paper proposed the FE-YOLOv5s vehicle-mounted infrared target detection model. Firstly, the PPA module was integrated into the backbone network to mitigate the feature information loss caused by downsampling operations. Secondly, based on the AFPN network and the DASI module, we developed a feature fusion network termed DAFPN. This network directly fuses feature information from non-adjacent scale layers and incorporates features from five different scale layers into the final feature output, further enhancing the feature representation capability of the targets. The target prediction layer was reconstructed to improve the model's recognition rate of small targets. Finally, MPDIoU was adopted as the bounding box loss function to enhance target localization accuracy. Experimental results demonstrated that the proposed model achieves mAP@0.5 scores of 88.1% on the FLIR dataset and 84.7% on the iRay vehicle-mounted infrared dataset, representing improvements of 7.2% and 3.2% over the YOLOv5s model. It effectively alleviates the problem of false and missed detections of infrared small targets while operating at 100 FPS, which confirms its potential for embedded deployment..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1044 (2025)
Defect recognition for unmanned aerial vehicle inspection based on global feature fusion of LiDAR images
Yongqiang ZHAO, Hao WU, Yi SUN, and Zhichun WANG
In order to ensure the safe and stable operation of transmission lines and accurately obtain the defect data required for their operation and maintenance, a defect recognition method for unmanned aerial vehicle inspection based on laser radar image feature fusion was proposed. Using laser image global feature point detIn order to ensure the safe and stable operation of transmission lines and accurately obtain the defect data required for their operation and maintenance, a defect recognition method for unmanned aerial vehicle inspection based on laser radar image feature fusion was proposed. Using laser image global feature point detection, and then using random histogram method to reduce the feature point vector set, global feature fusion was performed on the bottom layer, middle layer, and high layer respectively. Based on the laser image of the transmission line after global feature fusion, clustering algorithm was used to achieve intelligent recognition of transmission line drone inspection defects. According to the time and other parameters contained in the laser image captured by the drone during inspection, the defects of the transmission line were located to obtain the actual location of the transmission line defects. The experiment shows that this method can effectively fuse the global features of laser images, with a maximum global feature fusion degree of 0.99. The accuracy of defect recognition in different environments remains high, and the localization accuracy is close to 100%. In comparison, the average processing time of this method is also the shortest, only 5.6 seconds, which verifies its superior performance and application effect in the field of defect identification and localization in transmission line inspection..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1054 (2025)
Dynamic pose measurement accuracy evaluation technology based on mobile robot scene planning
Ningning LI, Binghua HU and Haiyang CHEN
Currently, the method of theoretical analysis and static verification is mainly used to evaluate the accuracy of visual measurement data in dynamic visual measurement tasks, which is inadequate for assessing the impact of error factors on measurement results during dynamic visual measurement processes. To address tihe Currently, the method of theoretical analysis and static verification is mainly used to evaluate the accuracy of visual measurement data in dynamic visual measurement tasks, which is inadequate for assessing the impact of error factors on measurement results during dynamic visual measurement processes. To address tihe limitation, this study designed and constructed an image dynamic pose measurement accuracy evaluation system. Based on the visual measurement principle and typical target motion patterns, the system comprehensively analyzed the error influence factors, planned and designed diverse experimental scenarios. Leveraging the mobile robot's advantages, including controllable motion, real-time dynamic pose acquisition and high-precision repeated positioning/posing, a ground simulation of target motion was conducted. By comparing the benchmark data generated by the mobile robot with the pose data obtained through visual measurement, error tracing and quantitative analysis were achieved, which provided effective technical support for the optimization design, feasibility demonstration and accuracy evaluation of specific taskthe implementation plan..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1063 (2025)
Visual measurement method for morphing wings based on active luminous markers
Xintao DU and Zhiwei XU
Dynamic deformation of aircraft wings during flight significantly impacts aircraft performance and safety. Binocular vision measurement technology enables non-contact, high-precision three-dimensional measurement, however, conventional methods are susceptible to ambient light interference and exhibit limited real-time Dynamic deformation of aircraft wings during flight significantly impacts aircraft performance and safety. Binocular vision measurement technology enables non-contact, high-precision three-dimensional measurement, however, conventional methods are susceptible to ambient light interference and exhibit limited real-time performance. This paper presented a novel binocular vision measurement method for wing deformation based on active luminous markers. Through the implementation of active luminous markers and a feature mask-based rapid centroid localization algorithm, the method effectively mitigated the issues of marker identification difficulty and measurement accuracy degradation caused by environmental lighting variations. Additionally, a error model for the displacement measurement of the binocular vision system was established based on error theory. Experimental results demonstrated that when measuring static deformation displacement and dynamic deflection angles of a morphing wing, the experimental errors correlated well with the proposed error model. The displacement errors were less than 0.5 mm and angular errors were within 0.5°. For dynamic measurements at frequencies up to 150 Hz, the correlation coefficient with the reference signal exceeded 0.97. The system offers advantages including robustness for environmental light interference, high real-time performance, and low equipment requirements, providing a practical solution for wing deformation monitoring..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1073 (2025)
On-orbit MTF evaluation of infrared spaceborne cameras based on three-bar target patterns
Kun QIAN, Weiwei XU, Xiaolong SI, Wenxin HUANG, Liming ZHANG, Jiawei LI, and Baoyun YANG
MTF(modulation transfer function) serves as a critical parameter for imaging quality evaluation of infrared remote sensing satellites; however, its on-orbit detection faces two major challenges: insufficient thermal stability of calibration targets and complexity in data processing. This study proposed a direct on-orbiMTF(modulation transfer function) serves as a critical parameter for imaging quality evaluation of infrared remote sensing satellites; however, its on-orbit detection faces two major challenges: insufficient thermal stability of calibration targets and complexity in data processing. This study proposed a direct on-orbit MTF detection method utilizing the synergistic three-bar and temperature-step targets. Through the target optimized design and fuzzy PID (proportional-integral-derivative) temperature control algorithm, the targets could achieve temperature uniformity (<0.5°C), stability (±0.6°C), and operational repeatability (>99%). By integrating Fourier optics theory and radiative transfer modeling with the computational principle of "object-image modulation separation", MTF values could be directly extracted at Nyquist frequency from remote sensing imagery. This approach could effectively eliminate errors caused by atmospheric interference, numerical differentiation, and parameter fitting inherent in conventional methods, providing high-precision technical support for quantitative applications of high-resolution infrared satellite systems..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1083 (2025)
Measurement method of infrared radiation characteristics of targets based on grayscale images of thermal imager
Yuanyuan ZHU, Wei MU, Lirong XU, Lina DENG, and Leilei SHI
Aiming at the problem that thermal imager of existing in-service equipment cannot obtain target radiation temperature information, a simple measurement method for obtaining target infrared radiation characteristics using video images of thermal imagers is studied. By setting the gain and the level parameters in fixed iAiming at the problem that thermal imager of existing in-service equipment cannot obtain target radiation temperature information, a simple measurement method for obtaining target infrared radiation characteristics using video images of thermal imagers is studied. By setting the gain and the level parameters in fixed integration time of thermal imager, the gray images of the blackbody at different temperatures are collected, and the gray and temperature models of the thermal imager are established. After collecting the target image, the target radiation temperature is retrieved by the model, and the target temperature is displayed in pseudo color. According to the target radiation temperature, the infrared radiation information such as target radiation brightness and radiation intensity can be calculated accordingly. The feasibility of this method is verified in the thermal imager experiment. The results show that the absolute error of retrieving the target radiation temperature is less than 4℃ and the relative error is less than 14% under the condition of certain gain and level. The error of target radiation temperature is large in field experiment. The model needs to be further improved. However, this method is feasible and has a strong application prospect..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1090 (2025)
Model of line structured light measurement system under influence of glass
Guofeng XIA, Bailin CAI and Xiangcheng CHEN
In order to eliminate the influence of glass thickness on the line structured light 3D measurement system, a new 3D measurement model was constructed. A camera refraction model was established based on Snell's law to accurately calculate the propagation path of light under the influence of glass. A new calibration In order to eliminate the influence of glass thickness on the line structured light 3D measurement system, a new 3D measurement model was constructed. A camera refraction model was established based on Snell's law to accurately calculate the propagation path of light under the influence of glass. A new calibration method was proposed, and the experimental results showed that the camera's reprojection error was 0.23 pixel. Meanwhile, a new plane correction method was proposed, which could quickly complete all laser plane corrections through the relationship between the laser plane, refractive surface, and glass thickness. The root mean square error of the point cloud fitting plane could reach 0.32 mm, and the absolute distance error could reach 0.26 mm. The experimental results show that the proposed method has good measurement accuracy and certain practicality in the industrial field..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1097 (2025)
High precision alignment and measurement of parallelism for multi-beam laser transceivers
Weijian LIU, Guojun DU, Xinyu ZHANG, Chao ZHANG, Chunhui WANG, and Zongyao OU
The parallelism of the optical axes between multi-beam laser transmitting and receiving system is a critical parameter for ensuring the performance of laser radar systems. To address the extremely high-precision registration challenge of achieving better than 10 μrad parallelism for a 48-beam laser transceiver system, The parallelism of the optical axes between multi-beam laser transmitting and receiving system is a critical parameter for ensuring the performance of laser radar systems. To address the extremely high-precision registration challenge of achieving better than 10 μrad parallelism for a 48-beam laser transceiver system, a high-precision alignment and testing method for transmitting-receiver registration was proposed. A measurement system for laser transmitting-receiving parallelism was constructed using a long-focal-length collimator and a beam analyzer. By accurately measuring the parallelism errors of the 48 laser beams, the spacing of the 48 receiving fibers of the receiving system was arranged and manufactured according to the measurement results to achieve high-precision alignment of the parallelism. A 20 m focal length collimator was applied to measuring a laser system with a divergence angle of 15 μrad for the transmitter and a reception field of view of 80 μrad. The achieved precision for aligning and measuring the parallelism of the multi-beam laser transceivers was 3.56 μrad. After alignment, the maximum measured parallelism error for the 48 beams was 8.81 μrad, demonstrating strong feasibility for practical engineering applications..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1104 (2025)
Response linearity of a short-exposure laser power meter
Tao YU, Zhaohui LIU, Qing SUN, and Liqiang ZHAO
Short-exposure laser power meters have the advantages of high measurement efficiency and low cost, and have a broad application prospect in high-power laser measurement. A short-exposure laser power meter was designed, and the temperature response characteristics of the detector under different power lasers and differeShort-exposure laser power meters have the advantages of high measurement efficiency and low cost, and have a broad application prospect in high-power laser measurement. A short-exposure laser power meter was designed, and the temperature response characteristics of the detector under different power lasers and different laser irradiation times were experimentally studied. The experimental results show that the temperature rise data at the end of the laser for 10 s can better characterize the laser power. The nonlinear deviation of the detector response is less than 3% when the duration of the detector is less than 1 s, and the nonlinear deviation of the detector response is not more than 5.5% when the duration of the laser is less than 2 s. A three-dimensional finite element model of the detector was developed. Simulations were carried out for scenarios with heat dissipation and without heat dissipation, respectively. The results show that the influence of heat dissipation on the nonlinearity of the detector response is small, the nonlinearity of the response in a short time is mainly caused by the heat transfer process, and the main factor affecting the linearity of the detector response in a long time is the measurement of signal-to-noise ratio..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1110 (2025)
Laser weak signal detection experiment
Xiaofei HU, Xiangfei MENG, Jun ZHANG, Tianze LI, Weichen REN, Yang WEN, Dong WANG, and Minglei HUO
The semi-active laser seeker has been widely used in weapon guidance systems due to its miniaturization, low cost, and high precision. Concerning the issues of low signal-to-noise ratio and weak detection ability of weak laser echo signals, this paper analyzed the relevant factors influencing weak echo signals. It was The semi-active laser seeker has been widely used in weapon guidance systems due to its miniaturization, low cost, and high precision. Concerning the issues of low signal-to-noise ratio and weak detection ability of weak laser echo signals, this paper analyzed the relevant factors influencing weak echo signals. It was proposed to suppress background noise from the perspective of the optical system, and optimize the indicators of the spot ellipticity and uniformity. By using high-speed direct sampling method for multifeature recognition and judgment, achiving feature extraction of weak signal complete waveform, improving signal-noise ratio.The results of laser spot quality and high-speed direct sampling experiments indicated that the ellipticity of the spot is about 95%, and the uniformity is 80%, the signal-noise ratio is greater than 10 dB, the detection limited distance is greater than 6 km. This study meets the needs of laser detection in terms of long-range terminal guidance, antiinterference, and has certain engineering application reference value..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1119 (2025)
Visible light indoor position perception method based on broad learning system
Feng ZHANG, Dingding ZHANG, Xiangyan MENG, and Xia PENG
To address the challenges of complex network architectures, a large number of hyperparameters, and gradient explosion encountered during deep learning training and position prediction in visible light indoor positioning,which can cause the problem of poor positioning timeliness and unstable accuracy ,this paper introduTo address the challenges of complex network architectures, a large number of hyperparameters, and gradient explosion encountered during deep learning training and position prediction in visible light indoor positioning,which can cause the problem of poor positioning timeliness and unstable accuracy ,this paper introduces a broad-learning approach for visible light indoor position perception. First, the light radiation data acquired from the indoor visible light environment was utilized as the feature node for the network. Subsequently, a prediction model for visible light indoor positioning based on the broad learning system was established. Next, the dimensionality of the network feature nodes was expanded. Finally, the pseudo-inverse matrix was computed to train and evaluate the network model. In the laboratory experiment conducted in a 4 m×4 m×3 m environment, the proposed algorithm demonstrated an average positioning error of 11.63 cm. The cumulative probability of prediction errors less than 10 cm was 52%, and that for errors less than 20 cm was 97%. Compared to BP(back propagation) and RBF(radial basis function) neural networks, the width learning network exhibited a 55.1% and 39.9% increase in positioning speed, respectively. The method in this paper improves the accuracy and speed of visible light indoor position perception, and provides a stable and reliable method for indoor position perception..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1126 (2025)
Sensing characteristics of long-period fiber grating based on chiral micro-taper structure of eccentric fiber
Ruicheng SONG, Mengyun LIU, Yao BAI, Xuelan HE, Tiebin WANG, Jian XING, Wenchao LI, and Shuanglong CUI
A long-period fiber grating (LPFG) based on chiral micro-taper structure was proposed. The chiral micro-taper structure was fabricated on the eccentric optical fiber through arc discharge technology, and its introduction significantly enhanced the performance of the sensor, which not only greatly improved its torsionalA long-period fiber grating (LPFG) based on chiral micro-taper structure was proposed. The chiral micro-taper structure was fabricated on the eccentric optical fiber through arc discharge technology, and its introduction significantly enhanced the performance of the sensor, which not only greatly improved its torsional sensitivity, but also enabled the sensor to have the ability to identify the torsional direction. To deeply explore the sensing characteristics of this chiral micro-taper structure long-period fiber grating, a method combining simulation and experiments was adopted. The research results show that the proposed sensor has the ability of direction discrimination, and its sensitivity is as high as 592.1 pm/(rad·m?1). Compared with long-period fiber gratings without chiral structures, it not only has the function of direction discrimination, but also its sensitivity is increased by nearly three times. This sensor features small size, simple preparation and high sensitivity, and has broad application prospects in fields such as health monitoring and precise measurement..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1135 (2025)
Fresnel transform orthogonal chirp modulation of non-orthogonal multiple access optical communication systems
Ying WANG, Feng ZHANG, Xia PENG, and Xiangyan MENG
The integration of power-domain non-orthogonal multiple access (PD-NOMA) with visible light communications (VLC) effectively improves spectrum utilization. However, in NOMA-VLC systems, orthogonal frequency division multiplexing (OFDM) is susceptible to indoor multipath effects, which degrades system reliability and coThe integration of power-domain non-orthogonal multiple access (PD-NOMA) with visible light communications (VLC) effectively improves spectrum utilization. However, in NOMA-VLC systems, orthogonal frequency division multiplexing (OFDM) is susceptible to indoor multipath effects, which degrades system reliability and communication efficiency. To address this issue, this paper proposed a chirp modulation technique based on the fresnel transformation to enhances data transmission reliability by suppressing multipath effects. The PD-NOMA-VLC system model under the visible light channel was analyzed, and a PD-NOMA-VLC system based on orthogonal chirp division multiplexing (OCDM) was designed. A fixed power allocation method was employed according to the users' channel gains to achieve NOMA multi-user multiplexing in the power domain.The discrete fresnel transform was utilized to perform OCDM modulation, effectively mitigating multipath effects. Theoretical analysis and experimental results demonstrated that the PD-NOMA-VLC system modulated by the proposed method met the forward error correction bit error rate threshold. The communication performance for user 1 and user 2 improves by 3.3 dB and 3.2 dB, respectively, with an average improvement of 3.25 dB for both users, effectively suppressing multipath effects. Furthermore, at modulation orders of 16, 32, 64, 128, and 256, the system achieves bit error rate (BER) performance improvements of 2.3 dB, 2.4 dB, 2.8 dB, 6.1 dB, and 4.2 dB, respectively, thereby enhancing communication efficiency while ensuring reliability..
Journal of Applied Optics
- Publication Date: Sep. 15, 2025
- Vol. 46, Issue 5, 1143 (2025)
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