2020

• Record 337 of
  
  Title:Automatic process parameters tuning and surface roughness estimation for laser cleaning
  
  Author(s):Liu, Haoting(1); Li, Jiacheng(1); Yang, Yong(2); Lan, Jinhui(1); Xue, Yafei(3)
  Source: IEEE Access  Volume: 8  Issue:   DOI: 10.1109/ACCESS.2020.2970086  Published: 2020  
  Abstract:An image analysis-based two-stage process parameters tuning and Surface Roughness (SR) estimation algorithm is proposed for the laser cleaning application. A Cartesian coordinate robot is utilized to collect image and implement cleaning. Before cleaning, in order to tune the proper laser parameters, first, the environment lighting is controlled for the metal image collection. Second, lots of classification features are computed for the images above. The Gray-Level Co-occurrence Matrix (GLCM) texture features, the concavo-convex region features, the histogram symmetry difference feature, and the imaging thermophysical property features are computed. Third, the initial laser parameters are created randomly and an iteration computation is performed: a Support Vector Machine (SVM) is used to forecast the cleaning effect; its inputs include the classification features and the initial laser parameters; its output is the cleaning effect degree. If the SVM output cannot fulfill user's demand, the laser parameters will be updated randomly. This iteration will be implemented constantly until the SVM output becomes valid. Then the laser cleaning will be performed. When estimating SR for the cleaned metal, multiple image features are calculated for the images after cleaning. The features include the Tamura coarseness, some GLCM features, and the convex region feature. To improve the prediction precision, different feature combinations are used for different cleaning effects. The linear function and the 3-order polynomial function are considered for the SR estimation. After tests, the accuracies of SVM, the SR prediction function, and the integrated SR control and estimation algorithm can be 90.0%, 80.0% and 80.0% approximately. © 2013 IEEE.
  Accession Number: 20200908231640
• Record 338 of
  
  Title:Position sensitive micro-channel plate based photon counting three-dimensional imaging for long space objects: Simulation and characteristics analysis
  
  Author(s):Yin, Haomeng(1,2); Zhao, Hui(1); Liu, Yong'an(1); Xia, Siyu(1); Fan, Xuewu(1); Sheng, Lizhi(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11567  Issue:   DOI: 10.1117/12.2580007  Published: 2020  
  Abstract:Position sensitive micro-channel plate (MCP) is a kind of high sensitivity detector with low noise, Combined with advanced time-correlated single photon imaging technique (TCSPC) could make a moderate aperture system be sensitive to only one single arriving photon. In this paper, a theoretical model of photon counting imaging with Position sensitive MCP was established and the factor of laser power affecting the detect possibility was analyzed. the three-dimensional point clouds data are generated using Monte Carlo simulation and the typical space target could be reconstructed three-dimensionally. Through the all-chain simulation model the comprehensive performance of the MCP based active three-dimensional imaging system could be analyzed from viewpoint of detection probability, ranging accuracy and signal to noise ratio etc. The application of the position sensitive MCP based active three-dimensional imaging system for long range space objects is verified in simulation condition. The results shows that only a single pulse energy of tens of mico-Joule is needed for the positive sensitive MCP based active three-dimensional imaging system to image the target at the hundreds of kilometers. the counting rate could reach 106 counts/s. And the ranging accuracy of this active three-dimensional imaging system for the objects at 300 kilometers could reach 0.1228meters by simulating with 50 mico-Joule single pulse power. © 2020 SPIE.
  Accession Number: 20205009602428
• Record 339 of
  
  Title:Non-contact heart rate and respiratory monitoring based on Imaging Photoplethysmography at fingertip
  
  Author(s):WenLong, Qiao(1,2); Liang, Zhou(2); Zhaohui, Liu(2); Jiangjun, Yu(1,2); Xiaoxiao, Sun(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11566  Issue:   DOI: 10.1117/12.2579405  Published: 2020  
  Abstract:In this paper, we use imaging photoplethysmography (IPPG) to realize non-contact measurement of blood volume change of human fingertip, which can avoid distortion of blood vessel wall caused by pressure applied to fingertip. We use CMOS color camera to collect signals and white LED as light source. In the process of signal processing, we abandon the traditional morphological filtering algorithm in the form of double-layer cascade, and use single-layer morphological filtering algorithm. Experiments show that the single-layer morphological filtering algorithm has a good effect of eliminating baseline drift of signals, and can perfectly retain the detail components of signals without shifting the transverse components. We proposed a peak-to-valley value detection algorithm to calculate the heart rate by detecting the time interval between the adjacent peaks value. The experiment compared the accuracy of calculating the heart rate by using the traditional fast Fourier transform and the heart rate based on peak-to-valley value detection. The respiration rate was detected by using the third-order Butterworth filter. The accuracy of heart rate monitoring can be achieved at 97.86% and the accuracy of respiration monitoring can be achieved at 95.02%. © 2020 SPIE. All rights reserved.
  Accession Number: 20204909589267
• Record 340 of
  
  Title:Improved genetic algorithm for intrinsic parameters estimation of on-orbit space cameras
  
  Author(s):Zhang, Gaopeng(1,2); Zhao, Hong(1); Zhang, Guangdong(2); Chen, Yaohong(2)
  Source: Optics Communications  Volume: 475  Issue:   DOI: 10.1016/j.optcom.2020.126235  Published: 15 November 2020  
  Abstract:Computer vision plays a key role to measure the relative posture and position between the spacecrafts, especially in various important space tasks. As one of the essential steps for computer vision, camera calibration is important for obtaining precise three-dimensional contours of the space target. However, it is impossible to use the traditional calibration targets to calibrate the space camera in orbit. To solve this problem, in this paper, we attack the on-orbit space camera calibration problem by using two steps. First, we only use two images of the solar panel, which is a commonly used element of majority human-made spacecraft, to generate an approximate initial estimation of the camera intrinsic parameters. In order to improve the robustness and accuracy of our method, the second step optimizes the initial solution by using an improved genetic algorithm (IGA). Simulated and real experiments prove that the proposed method is accurate and flexible, and shows good robust performance. Therefore, our method has realistic significance for various space tasks. © 2020 Elsevier B.V.
  Accession Number: 20202808915622
• Record 341 of
  
  Title:Optimized design for the supporting structure of a large aperture mirror
  
  Author(s):Rui, Wang Jia(1); Tao, Yang Hong(2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11570  Issue:   DOI: 10.1117/12.2580254  Published: 2020  
  Abstract:With the continuous development of optical technology in recent years, the pace of human exploration of space has further accelerated. Space remote sensing technology is widely used in surveying and mapping, environmental monitoring and other fields. Therefore, the requirements for space optics technology are gradually increasing. In order to reduce the launch cost and the deformation of the supporting member and the main mirror base under its own gravity, a lightweight design must be carried out. Therefore, under the premise of ensuring the rigid body displacement of the mirror body and the error of the mirror shape, lightweight has become a key requirement for the development of remote sensing technology. By comparing various supporting structures, the spatial freedom of the mirror is calculated. Choose a combination of 9-point post-support and 3-point peripheral support. Compare and select the materials commonly used in the structure of the supporting part and the main mirror base. Although the support structure adopts topology optimization, a very effective support method can be obtained, but the final result cannot be universally applied to the support structure of mirrors with different apertures. Therefore, this paper determines the design structure of the relationship between the mirror support position, the fundamental frequency and the surface shape accuracy and the support structure parameters based on the flexibility matrix. For the rigid parts of the supporting structure and the main mirror base, simulation software was used to optimize the design of the initial design structure to remove excess materials. The final main mirror base lightweight rate was 36.6%, and the triangular plate lightweight rate was 65.9%. The static analysis and modal analysis of the supporting scheme are carried out by analysis software. After optimization, the shape accuracy of the primary mirror under its own weight is better than λ/50. Structural resonance will seriously affect the use and life of the equipment. Therefore, the modal analysis is performed, and the fundamental frequency is within a reasonable range during the optimization process. The simulation results show that the first-order fundamental frequency is 836.55 Hz. The analysis results show that while ensuring the shape accuracy of the primary mirror, the lightweight design of the mirror support assembly is realized. © 2020 SPIE. All rights reserved.
  Accession Number: 20204909580485
• Record 342 of
  
  Title:Hybrid multifocal structured illumination microscopy with enhanced lateral resolution and axial localization capability
  
  Author(s):Wang, Zhaojun(1,2); Cai, Yanan(1); Qian, Jia(1); Zhao, Tianyu(1); Liang, Yansheng(1); Dan, Dan(1); Lei, Ming(2); Yao, Baoli(1)
  Source: Biomedical Optics Express  Volume: 11  Issue: 6  DOI: 10.1364/BOE.391024  Published: June 1, 2020  
  Abstract:Super-resolution (SR) fluorescence microscopy that breaks through the diffraction barrier has drawn great interest in biomedical research. However, obtaining a high precision three-dimensional distribution of the specimen in a short time still remains a challenging task for existing techniques. In this paper, we propose a super-resolution fluorescence microscopy with axial localization capability by combining multifocal structured illumination microscopy with a hybrid detection PSF composed of a Gaussian PSF and a double-helix PSF. A modified reconstruction scheme is presented to accommodate the new hybrid PSF. This method can not only recover the lateral super-resolution image of the specimen but also retain the specimen's depth map within a range of 600 nm with an axial localization precision of 20.8 nm. The performance of this approach is verified by testing fluorescent beads and tubulin in 293-cells. The developed microscope is well suited for observing the precise 3D distribution of thin specimens. © 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.
  Accession Number: 20202308792107
• Record 343 of
  
  Title:High-precision resin layer polishing of carbon fiber mirror based on optimized ion beam figuring process
  
  Author(s):Ding, Jiao Teng(1,2); Fan, Xue Wu(1); Xu, Liang(1); Ma, Zhen(1); Wang, Yong Jie(1); Wu, Xiao Ge(1)
  Source: Optik  Volume: 206  Issue:   DOI: 10.1016/j.ijleo.2019.163575  Published: March 2020  
  Abstract:Based on the advantages of stress-free and non-liquid environment, ion beam polishing is the ideal processing technology for the Resin modified layer polishing of the carbon fiber mirror. Since the glass transition temperature of the resin is low, the energy absorbed by the surface of the mirror during ion beam processing can cause localized high temperatures, which can lead to the risk of resin softening. The finite element analysis software was used to simulate the heat transfer process of Ion beam acting on the resin modified layer. The optimum process parameters of the ion beam polishing were determined. At the same time, the resin layer surface polishing test was completed. The experimental results show that the surface polishing of the resin modified layer can be achieved by ion beam processing, and it has the convergence property and the correctness of the theoretical model is Verified.In addition, according to the process instability phenomenon in the ion beam figuring of carbon fiber-based resin modified layer, analytical research on factors affecting the accuracy of ion beam processing were carried out. The effects of various factors on the processing precision of carbon fiber resin layer were analyzed by combing and theoretical analysis,combined with experimental research to determine the amount of influence, and finally put forward corresponding solutions. © 2019 Elsevier GmbH
  Accession Number: 20195107878899
• Record 344 of
  
  Title:Real-time long-term tracker with tracking–verification–detection–refinement
  
  Author(s):Liao, Jiawen(1,2,3); Qi, Chun(2); Cao, Jianzhong(1); Ren, Long(1,2,3); Zhang, Gaopeng(1)
  Source: Journal of Visual Communication and Image Representation  Volume: 72  Issue:   DOI: 10.1016/j.jvcir.2020.102896  Published: October 2020  
  Abstract:Long-term tracking is one of the most challenging problems in computer vision. In this paper, we make full use of the Discriminative Correlation Filter (DCF), and propose a real-time long-term tracker by exploiting a joint tracking–verification–detection–refinement framework. We utilize a DCF which is updated aggressively to estimate translation and scale variation of the target. Subsequently, a passively updated DCF checks the reliability of the tracking result. Once the result is not reliable, we evoke the proposed optimized candidate detector to generate a small number of relatively high quality candidates. Finally, one DCF with an adaptive online learning rate is adopted to refine the predictions that the sparse candidates inferred. In addition, we employ a selection mechanism for the correlation responses to maintain reliable samples effectively. Extensive experiments show that the proposed method performs favorably against lots of state-of-the-art methods while running more than 30 frames per second on single CPU. © 2020 Elsevier Inc.
  Accession Number: 20203609147464
• Record 345 of
  
  Title:High-precision speed control of the turntable of a circumferential scanning imaging system
  
  Author(s):Wu, Shao-Bo(1,2); Su, Xiu-Qin(1); Wang, Kai-Di(1,2)
  Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering  Volume: 28  Issue: 6  DOI: 10.3788/OPE.20202806.1353  Published: June 1, 2020  
  Abstract:In this study, a composite control algorithm was developed for controlling the turntable speed of a circumferential scanning imaging system (ICSIS) driven by a permanent magnet synchronous motor (PMSM) to obtain stable high-resolution images. Based on the load characteristics of the turntable and the mathematical model of the PMSM, a single-sampling rate control system model, comprising the mechanical parameter uncertainty and fast-changing torque disturbance, was established. The fast nonsingular terminal sliding mode (FNTSM) control and an extended high-gain observer were used in designing the speed-tracking controller. The maximum torque current ratio control was determined through another FNTSM control. Finally, the performance of the speed tracking control based on the above composite algorithm was analyzed and verified. The experimental results show that when the turntable speed is set to 120 or 240 r/min, the speed tracking error is less than 0. 1%. Compared with the proportional-integral control, FNTSM control, and linear sliding mode control+observer, the governing system with the proposed algorithm was characterized by no overshooting, stronger anti-disturbance, and higher speed-tracking precision, which enabled the ICSIS to capture clear and stable circumferential images. © 2020, Science Press. All right reserved.
  Accession Number: 20202608879110
• Record 346 of
  
  Title:Investigation of dwell time based on lucy-richardson algorithm and gercherg surface continuation algorithm
  
  Author(s):Qian, XinJie(1,2); Ma, Zhen(1); Yao, Yongsheng(1,2); Shen, Le(1)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11568  Issue:   DOI: 10.1117/12.2579836  Published: 2020  
  Abstract:Computer-controlled optical surface forming technology (CCOS) can greatly improve the processing accuracy and processing efficiency of optical mirrors. The most critical problem is the solution of dwell time, which will directly affect the final convergence of the surface shape. it is found through analysis that the solution of the dwell time is a deconvolution process, which is the same as the mathematical model of the Lucy-Richardson algorithm in image restoration technology, so the algorithm can be applied to Solution of dwell time; At the same time, in order to eliminate the high-frequency shape errors caused by discontinuities at the edges of the face shapes, the original shapes need to be extended to achieve smooth connections. The two-dimensional Gercherg bandwidth-limited continuation algorithm can achieve this requirement. The simulation results show that the root mean square value (rms) and peak-valley value (pv) converge from the initial 0.2534λ, 1.494λ (λ=632.8nm) to 0.0158λ and 0.393λ, which proves the effectiveness of the algorithm. Compared with the Lucy-Richardson algorithm, other traditional solving methods have simpler calculation process, higher calculation efficiency, and higher convergence rate. © 2020 SPIE. All rights reserved.
  Accession Number: 20204909580450
• Record 347 of
  
  Title:Design and improvement of a type of filter wheel in remote sensing
  
  Author(s):Song, Yang(1); Shen, Zeyi(1); Xin, Wei(1); Zhang, Xianghui(1); Lin, Shangmin(1,2)
  Source: Proceedings of SPIE - The International Society for Optical Engineering  Volume: 11570  Issue:   DOI: 10.1117/12.2572943  Published: 2020  
  Abstract:The field of laser remote sensing and laser detection is becoming a research hot spot. Filter wheel is an important part in the process of remote sensing. The purpose of filter wheel is to choose the proper band wavelength of light to realize the specific functions. The paper made a design scheme of a type of filter wheel component and then did structural analysis under different and strict load cases. These various load cases were used to prove that if the component could be safe during the launching time of the rocket. For the initial design scheme, the situation was not good. After that, the paper made an improved design by using special flexible supports, which had flexible links and support glue. At last, structural analysis was made. The result of analysis showed that the improvement was effective and successful. © 2020 SPIE. All rights reserved.
  Accession Number: 20204909580493
• Record 348 of
  
  Title:Implementation of IMM Kalman filtering feed-forward compensation technology in search and track systems
  
  Author(s):Lin, Di(1,2); Wu, Yi-Ming(1); Zhu, Fan(1)
  Source: Kongzhi yu Juece/Control and Decision  Volume: 35  Issue: 5  DOI: 10.13195/j.kzyjc.2018.1103  Published: May 1, 2020  
  Abstract:The UAV has large maneuver and angular velocity motions, which puts high requirments on the servo tracking accuracy of the ground search and tracking system. In order to improve the tracking accuracy of the ground search and tracking system, servo feed-forward compensation technology is often added. Accurate target velocity and acceleration estimation becomes the difficulty of feed-forward compensation control. IMM Kalman filtering is used to estimate the velocity and acceleration information of the target, and it is used as the input of servo feed-forward compensation system to eliminate the miss distance error caused by the velocity and acceleration of the target. The actual system test results show that the tracking accuracy of the search and tracking system is more than three times higher than that of the conventional Kalman filter compensation by using the IMM Kalman filter feed-forward compensation technology, and the model verification is effective. © 2020, Editorial Office of Control and Decision. All right reserved.
  Accession Number: 20202108693593