Journals >Optics and Precision Engineering
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2025
Volume: 33 Issue 3
13 Article(s)
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Dual-comb based dynamic radius external reference measurement of precision centrifuge
Siyu ZHOU, Yuxuan MA, Dong HE, Chunjing ZHANG, Li TANG, Xin LIU, Shanshan WANG, and Guanhao WU
To achieve precise measurement of the dynamic radius of a precision centrifuge， an external reference measurement system was established utilizing dual-comb ranging technology. This approach capitalizes on the advantages of high speed， exceptional precision， and absolute distance measurement， and incorporates a spatialTo achieve precise measurement of the dynamic radius of a precision centrifuge， an external reference measurement system was established utilizing dual-comb ranging technology. This approach capitalizes on the advantages of high speed， exceptional precision， and absolute distance measurement， and incorporates a spatial optical configuration featuring a cylindrical mirror and focusing path. Initially， the structure and principles underlying the external reference measuring device based on dual-comb ranging are presented. Subsequently， an analysis is conducted regarding the influence of curvature radius and alignment errors of the cylindrical mirror target on the precision of dynamic radius measurements， accompanied by the proposal of a method for mutual compensation error correction. An experimental system has been constructed to assess the dynamic radius of the precision centrifuge across various acceleration levels. Both static and dynamic measurement precisions of the system are evaluated， and sources of measurement errors are identified alongside a proposed system optimization plan. Experimental results demonstrate that the system effectively measures dynamic radius variations under accelerations ranging from 0g to 15g. With 20 sliding averages at a repetition frequency difference of 2 kHz， the dynamic measurement accuracy exceeds 0.56 μm， with a maximum dynamic radius recorded at 204.90 μm. This methodology satisfies the stringent requirements for high-speed and high-precision dynamic radius measurements， thereby enhancing the accuracy of centrifuge acceleration calibration..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 349 (2025)
Mid-infrared standing wave V-cavity ring-down 14CO2 spectral detection
Hongwei ZHANG, Gang ZHAO, Bingchi ZHU, Kang JIAO, Di ZHU, Zhe SHI, Tianyue YANG, Xiaojuan YAN, Jiaqi YANG, Weiguang MA, and Suotang JIA
To address the pressing need for highly sensitive detection of gaseous pollutants in nuclear facilities， a detection technique employing cavity-enhanced absorption spectroscopy of 14CO2 was developed. This method incorporates a standing wave V-shaped cavity alongside a quantum cascade laser. A mid-infrared absorption sTo address the pressing need for highly sensitive detection of gaseous pollutants in nuclear facilities， a detection technique employing cavity-enhanced absorption spectroscopy of 14CO2 was developed. This method incorporates a standing wave V-shaped cavity alongside a quantum cascade laser. A mid-infrared absorption spectroscopy detection system was constructed， successfully achieving highly sensitive detection of 14CO2 gas. The system utilizes a standing wave V-shaped cavity comprising three high-reflectance mirrors， which effectively doubles the spectral resolution without necessitating an increase in the physical length of the optical cavity. By incrementally scanning the laser wavelength to sequentially provoke the absorption events of adjacent cavity modes， comprehensive molecular spectral measurements are obtained while maintaining a high signal-to-noise ratio of cavity absorption spectroscopy signals. Furthermore， to mitigate variations in trigger positions caused by fluctuations in cavity length and laser frequency drift， dynamic correction of the step voltage values was implemented during the experiment， resulting in long-term stability of 14CO2 spectral measurements. Allan variance analysis revealed that the detection limit of this system is 2.5×10-10 cm-1， corresponding to a minimum detectable concentration of 1.2×10-12 for 14CO2. This technology holds significant promise for monitoring the emission of radioactive carbon dioxide in the exhaust gases from nuclear power plants..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 359 (2025)
Detection of seed viability by photoacoustic carbon dioxide sensing
Zhenyu GUO, Yashan FAN, Baojie ZHAI, Ruijun XIE, Zhijin SHANG, Yali TIAN, Xuanbing QIU, and Chuanliang LI
In order to investigate the relationship between variations in carbon dioxide （CO2） concentration and seed vitality during respiration， a CO2 photoacoustic sensing system utilizing a differential Helmholtz photoacoustic cell was designed. The system's performance was evaluated by measuring the CO2 production rate oIn order to investigate the relationship between variations in carbon dioxide （CO2） concentration and seed vitality during respiration， a CO2 photoacoustic sensing system utilizing a differential Helmholtz photoacoustic cell was designed. The system's performance was evaluated by measuring the CO2 production rate of south japonica rice seeds exhibiting varying levels of vitality. An independent signal processing module based on a field programmable gate array （FPGA） development board was developed to facilitate precise regulation of laser drive current and demodulation of photoacoustic signals. Through optimization of modulation frequency， laser modulation depth， working pressure， and other system parameters， optimal performance was achieved， with an integration time of 1 089 s and a detection limit of 0.6×10-6. In accordance with national standard GB/T 3543.1， a germination experiment involving 30 g of south japonica rice seeds was conducted. Linear fitting analysis was performed using CO2 evolution concentration data obtained from the photoacoustic sensing experiment. The results demonstrate that the seed respiration rate of south japonica rice is directly proportional to seed vitality， with a correlation coefficient of 0.979. This finding provides a valuable reference for assessing rice seed vitality through photoacoustic spectroscopy..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 367 (2025)
Technologies of real-time non-line-of-sight imaging based on time-of-flight array
Yuan HAN, Youzhi LI, Zhenchen JI, Hongxu AI, Jiaqi YAO, Yanqiu WANG, Fu ZHENG, and Zhibin SUN
To address the challenges associated with slow imaging speed， limited imaging range， and the complexity and high costs of existing non-line-of-sight （NLOS） imaging technologies， a novel real-time NLOS imaging method based on array time-of-flight （ToF） principles was proposed. A theoretical model for three-dimensional （To address the challenges associated with slow imaging speed， limited imaging range， and the complexity and high costs of existing non-line-of-sight （NLOS） imaging technologies， a novel real-time NLOS imaging method based on array time-of-flight （ToF） principles was proposed. A theoretical model for three-dimensional （3D） scattering NLOS imaging utilizing a planar array configuration was established， facilitating the investigation of the effects of imaging distance and light source illumination angle on system reconstruction outcomes and overall performance. An evaluation index for ToF NLOS 3D imaging was developed. This method employs an 850 nm modulated laser as the optical signal source， with a ToF camera functioning as the sensor to capture third-order forward scattering signals from concealed targets illuminated through an intermediate plane. The hidden target is reconstructed using depth information obtained from a demodulation algorithm. Experimental results demonstrate that the system can achieve real-time NLOS reconstruction of small targets， such as a plaster statue measuring 15 cm × 19 cm × 30 cm， when both the intermediate plane and NLOS objects are approximated as Lambertian surfaces within a distance of 3.5 m. The illumination angle of the light source can be adjusted between 60 and 90 degrees， resulting in a real-time imaging speed of 2.056 5 frame/s. The system features a pixel resolution of 320 × 240， with a maximum target area pixel size of 150 × 100， and a minimum horizontal distance for multiple target images without aliasing of 3.5 cm. This paper introduces key technologies for real-time NLOS imaging using array ToF， highlighting significant advancements in imaging range， speed， resolution， and interference resistance..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 377 (2025)
Adaptive focusing evaluation algorithm for optical imaging of wafer positioning marks
Jin YANG, Hangying ZHANG, Kai MENG, and Peihuang LOU
The wafer positioning mark is characterized by its small size and diverse shapes. Traditional focus evaluation functions exhibit limitations， including poor stability and low sensitivity during computation. To address these challenges， an adaptive focus evaluation algorithm based on multi-directional gradient variance The wafer positioning mark is characterized by its small size and diverse shapes. Traditional focus evaluation functions exhibit limitations， including poor stability and low sensitivity during computation. To address these challenges， an adaptive focus evaluation algorithm based on multi-directional gradient variance was proposed in this paper. Initially， feature edge pixel points of the mark image were adaptively sampled and extracted. Subsequently， a multi-directional gradient function， tailored for wafer positioning marks， was developed by integrating the Brenner function and the Roberts function. The sampled pixel points were then evaluated to derive the initial focus evaluation function value. Finally， the variance of the initial focus evaluation function values across the image set was computed， thereby enhancing the robustness of the function against noise and yielding the final focus evaluation function value. Experimental results indicate that the proposed algorithm reduces fluctuations in flat areas by 61.49% and enhances sensitivity by a factor of 2.56 compared to traditional evaluation algorithms. This innovative approach provides a superior calculation strategy for achieving high-sensitivity automatic focusing of wafer positioning marks and other micro-nano mark images characterized by distinct edge feature structures..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 389 (2025)
Magnetorheological elastomer uniform polishing method for shell components
Bo XUE, Lijun ZHU, Xing SU, Li CHEN, Tao ZHOU, Jianfei ZHANG, Kuo HAI, and Wen HUANG
This study introduces a novel uniform polishing method for the ultra-precision finishing of the inner surfaces of thin-shell components， based on the principles of magnetorheological elastomer （MRE） polishing. The methodology involves the application of a magnetic field to the outer surface of the component， enabling pThis study introduces a novel uniform polishing method for the ultra-precision finishing of the inner surfaces of thin-shell components， based on the principles of magnetorheological elastomer （MRE） polishing. The methodology involves the application of a magnetic field to the outer surface of the component， enabling precise control of the MRE pressure on the inner surface， thereby facilitating uniform polishing. Magneto-elastic coupling simulations of the MRE were conducted using COMSOL Multiphysics software to determine the polishing pressure， its distribution across the component surface， and the velocity distribution within the polishing area. A material removal function model was developed based on the Preston equation， which was subsequently discretized and sampled to derive the material removal vector. The residence time at each point in the polishing area was calculated using the non-negative least squares method. To validate the proposed approach， a polishing experiment was conducted under a magnetic field of 0.32 T， utilizing a magnetorheological MRE device to polish a fused quartz glass workpiece measuring 60 mm × 60 mm × 1 mm for a duration of 78 minutes. The experimental results indicated that controlling the residence time at each point achieved an average material removal depth of 84.4 nm， with a fluctuation range of 10.9%， thereby attaining a uniform surface finish. These findings substantiate the effectiveness of the proposed method in achieving uniform polishing of the inner surfaces of thin-shell components..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 402 (2025)
Influence of vacuum adsorption mounting on adjustment of lens surface shape
Xi WANG, Peng YAO, Jiarong BAI, Xiang LIU, Fengguo LI, Dongkai CHU, Shijie HOU, and Zonglei WEI
Vacuum adsorption clamping ensures a uniform distribution of force on the lens， mitigates the occurrence of surface scratches， and is widely utilized in the processing and assembly of optical machine systems. This study examines the impact of vacuum adsorption on the surface morphology of thin plane lenses. Initially， Vacuum adsorption clamping ensures a uniform distribution of force on the lens， mitigates the occurrence of surface scratches， and is widely utilized in the processing and assembly of optical machine systems. This study examines the impact of vacuum adsorption on the surface morphology of thin plane lenses. Initially， the theory of circumferentially simply supported flat plate deformation， in conjunction with thin plate theory， is applied to analyze how various contact states between the lens and fixture， as well as differing vacuum levels， influence lens deformation. Subsequently， a fluid-solid coupling model is established to investigate the effects of various negative pressure conditions on lens surface geometry， thereby validating the feasibility of employing vacuum adsorption to regulate lens shape. Finally， adsorption clamping experiments are conducted to assess changes in lens morphology before and after vacuum application. The findings reveal a reduction in the error of the lens adsorption surface shape from 10 μm to 7 μm， while the gap between the lens and fixture decreased from 9 μm to 4 μm， reaching a minimum of 0.8 μm. In conclusion， negative pressure adsorption enhances the conformity of the lens adsorption surface to the fixture surface， thereby substantiating the efficacy of vacuum adsorption as a method for regulating lens surface shape. The proposed vacuum adsorption clamping technique not only improves the precision of lens processing and assembly but also effectively minimizes the impact of initial surface shape errors on the optical system..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 416 (2025)
Three-degree-of-freedom parallel piezoelectric stick-slip platform
Lingwei MENG, Yiling YANG, Gaohua WU, Yuguo CUI, and Yanding WEI
In addressing the performance requirements associated with macro-stroke applications， such as high precision， substantial load capacity， and multi-degree-of-freedom functionality for tasks involving cell puncture， micro-operation， and micro-assembly， a novel three-degree-of-freedom parallel stick-slip driving platform In addressing the performance requirements associated with macro-stroke applications， such as high precision， substantial load capacity， and multi-degree-of-freedom functionality for tasks involving cell puncture， micro-operation， and micro-assembly， a novel three-degree-of-freedom parallel stick-slip driving platform utilizing piezoelectric compliant mechanisms was proposed. The integration of macro fiber composite with the arch driving mechanism constructed a driving unit that facilitates stick-slip actuation， enabling large-scale， high-precision motion of the parallel platform. Furthermore， the implementation of cylindrical support significantly enhanced the platform's load capacity， while universal bearings mitigate non-driven friction， thereby improving overall motion performance. The finite element method was utilized to establish the static model of the compliant arch driving unit， followed by simulations and analysis of output displacement and natural frequency. An experimental test system was subsequently developed to validate the output performance of the platform. Experimental results indicate that the piezoelectric stick-slip platform， operating in stepping mode， achieves maximum single-step translation displacements of 294.7 μm and 304.5 μm along the X and Y axes， respectively， as well as a maximum single-step rotation angle of 9.96 mrad around the Z axis， with a maximum vertical load capacity of 110 N. In scanning mode， the displacement resolutions for translation and rotation are recorded at 6 nm and 0.28 μrad， respectively. Thus， the designed parallel piezoelectric stick-slip platform effectively satisfies the performance criteria required for precision micromanipulation tasks..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 427 (2025)
Binocular vision-based trackside pantograph anomaly detection under strong environmental noise
Jin ZHAO, Yin GUO, Shibin YIN, Lei GUO, and Jigui ZHU
To address the challenge posed by significant environmental noise that disrupts the parameters of binocular vision systems in pantograph anomaly detection-thereby compromising the accuracy of disparity maps and detection precision-an improved stereo matching method was developed and integrated with anomaly feature deteTo address the challenge posed by significant environmental noise that disrupts the parameters of binocular vision systems in pantograph anomaly detection-thereby compromising the accuracy of disparity maps and detection precision-an improved stereo matching method was developed and integrated with anomaly feature detection for this application. This study employs an expanded neighborhood cost calculation and weighted cost aggregation to mitigate the inaccuracies associated with binocular epipolar geometry induced by environmental noise or structural alterations. The local binary pattern method was utilized to compute the cost distribution function， rendering the algorithm applicable for fixed scene detection. Additionally， the disparity search space was constrained to enhance efficiency for real-time trackside detection. Subsequently， abnormal feature detection was conducted on the reconstructed 3D point cloud to derive measurement outcomes. The efficacy of this approach was validated within a pantograph anomaly detection system at railway stations. Experimental results indicate that the proposed algorithm enhances time efficiency by over 30% and measurement accuracy by more than 60% when compared to conventional algorithms， thus effectively addressing the issues of low efficiency and insufficient accuracy in rail transit on-site detection equipment..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 438 (2025)
Ultra-wideband multi-anchor resilient-assisted vision/inertial tightly coupled navigation
Haolong LUO, Jiansheng LI, Zhitao XU, Li WANG, Shitian ZHANG, and Guangyun LI
Due to the limitations of distance measurement from a single ultra-wideband （UWB） anchor， which provides only one-dimensional information， significant enhancement in system accuracy and robustness is constrained. To address this issue， a UWB multi-anchor resilient-assisted vision/inertial tightly coupled navigation metDue to the limitations of distance measurement from a single ultra-wideband （UWB） anchor， which provides only one-dimensional information， significant enhancement in system accuracy and robustness is constrained. To address this issue， a UWB multi-anchor resilient-assisted vision/inertial tightly coupled navigation method was proposed， which obviates the necessity of pre-obtaining UWB anchor positions and demonstrates universal applicability. Initially， based on the plug-and-play concept， an online asynchronous positioning estimation method was introduced to effectively and timely utilize UWB anchor information. Subsequently， a resilient factor graph optimization framework was employed to construct a tightly coupled factor graph model for vision-inertial UWB fusion， facilitating tightly coupled navigation that integrates information from vision， inertial sensors， and multiple UWB anchors. The proposed method was validated using both the open-source VIRAL dataset and datasets collected from real-world environments. Experimental results indicate that， in comparison to state-of-the-art open-source algorithms VINS-MONO and VIR-SLAM， the positioning accuracy of the proposed method improved by an average of 30.61% and 23.19%， respectively. These findings underscore that the UWB multi-anchor resilient-assisted vision/inertial tightly coupled navigation method provides enhanced positioning accuracy and improved robustness..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 452 (2025)
Automatic measurement of folding wing geometry size based on improved Canny-FAST
Yindi CAI, Zimeng SUN, Shixiong LI, Chao NIU, Taikun GE, and Xinwei GAO
In order to achieve high-precision and high-efficiency measurements of the folding wing geometry of non-standard complex components， an automatic measurement method based on an improved Canny-FAST algorithm was proposed. This method addresses the challenges of low measurement accuracy， poor repeatability， and reduced eIn order to achieve high-precision and high-efficiency measurements of the folding wing geometry of non-standard complex components， an automatic measurement method based on an improved Canny-FAST algorithm was proposed. This method addresses the challenges of low measurement accuracy， poor repeatability， and reduced efficiency associated with traditional manual measurement techniques. The Douglas-Peucker algorithm was integrated into the conventional Canny-FAST approach to enhance contour feature simplification， thereby improving extraction accuracy and robustness. An automatic measurement system for folding wing geometry was developed based on this method. By establishing seamless interactive communication between the measurement module and the motion module， measurement that is automatic， high-precision， stable， and efficient was realized. The performance of the self-developed automatic measurement system is verified， with length measurement accuracy exceeding 65 μm and angle measurement accuracy better than 0.049°， thus meeting the requirements for folding wing geometry assessments..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 466 (2025)
Fast dehazing for large format oblique images based on improved dark channel prior
Huang HUANG, Huan OUYANG, Yang DONG, Xin HE, and Xinghao ZHAO
The traditional dark channel dehazing algorithm is limited by its inability to adequately remove haze from the distal regions of large-format oblique images and suffers from low processing efficiency. To address these challenges， an improved dark channel prior-based dehazing algorithm for oblique images was proposed inThe traditional dark channel dehazing algorithm is limited by its inability to adequately remove haze from the distal regions of large-format oblique images and suffers from low processing efficiency. To address these challenges， an improved dark channel prior-based dehazing algorithm for oblique images was proposed in this paper. Initially， a rapid compensation method for the dark channel was employed， utilizing block-level and pixel-level window weighted fusion to enhance transmittance estimation. Subsequently， the dark channel prior was integrated with the radiative transfer equation to establish a haze distribution model and calculate transmittance. The atmospheric light value was then estimated to complete the dehazing process. Furthermore， a parallel computing scheme was designed to enhance dehazing speed. Experimental results indicate that the proposed algorithm effectively mitigates the effects of uneven haze distribution， thus significantly improving the quality of hazy images. In scenes with dense haze， image entropy and average gradient values increase by approximately 22.7% and 30.0%， respectively. Additionally， the dehazing speed during batch processing is approximately 11 times faster than that of traditional dark channel algorithms， demonstrating a substantial enhancement in processing efficiency..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 476 (2025)
Secret key extraction from atmospheric wireless optical channels by combing with generative adversarial network
Zhuozhan TIAN, Chunyi CHEN, Xiaojuan HU, Haiyang YU, Yanfeng LI, and Fang WANG
Wireless optical channel key extraction serves as an effective method for achieving physical layer security， wherein legitimate parties generate a key sequence by detecting and estimating the features of the optical channel. Eavesdroppers， however， may capture key-related information through optical signals outside theWireless optical channel key extraction serves as an effective method for achieving physical layer security， wherein legitimate parties generate a key sequence by detecting and estimating the features of the optical channel. Eavesdroppers， however， may capture key-related information through optical signals outside the legitimate party's receiving aperture. To address this challenge， a novel key extraction scheme was proposed. Initially， an enhanced generative adversarial network model was utilized to enable legitimate parties to accurately estimate channel features relevant for key extraction from the measured channel sequences. Subsequently， a random quantization alternating method was employed on the estimated channel feature sequences to derive the initial keys independently. Experimental results demonstrate that the key sequences generated by the legitimate parties exhibit high consistency， with the correlation coefficient between the channel feature sequences estimated by Alice and Bob reaching 0.998 3 in a 25 dB SNR environment. Furthermore， the initial key disagreement rate produced by Alice and Bob is 1.3×10-4 ，which is significantly reduced by the proposed scheme. The shared key obtained after information negotiation by the legitimate parties successfully passes the NIST randomness test， underscoring the efficacy and robustness of the proposed method in enhancing key extraction reliability..
Optics and Precision Engineering
- Publication Date: Feb. 10, 2025
- Vol. 33, Issue 3, 486 (2025)
