2017
2017
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Record 457 of
Title:Design of control system for piezoelectric deformable mirror based on fuzzy self-adaptive PID control
Author(s):Xiao, Nan(1,2); Gao, Wei(1); Song, Zongxi(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10463 Issue: DOI: 10.1117/12.2284441 Published: 2017Abstract:With the rapid development of adaptive optics technology, it is widely used in the fields of astronomical telescope imaging, laser beam shaping, optical communication and so on. As the key component of adaptive optics systems, the deformable mirror plays a role in wavefront correction. In order to achieve the high speed and high precision of deformable mirror system tracking control, it is necessary to find out the influence of each link on the system performance to model the system and design the controller. This paper presents a method about the piezoelectric deformable mirror driving control system. ? 2017 SPIE.Accession Number: 20180304654853 -
Record 458 of
Title:Space-based detection of space debris by photometric and polarimetric characteristics
Author(s):Pang, Shuxia(1,2); Wang, Hu(1); Lu, Xiaoyun(1,2); Shen, Yang(1,2); Pan, Yue(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10463 Issue: DOI: 10.1117/12.2285141 Published: 2017Abstract:The number of space debris has been increasing dramatically in the last few years, and is expected to increase as much in the future. As the orbital debris population grows, the risk of collision between debris and other orbital objects also grows. Therefore, space debris detection is a particularly important task for space environment security, and then supports for space debris modeling, protection and mitigation. This paper aims to review space debris detection systematically and completely. Firstly, the research status of space debris detection at home and abroad is presented. Then, three kinds of optical observation methods of space debris are summarized. Finally, we propose a space-based detection scheme for space debris by photometric and polarimetric characteristics. ? 2017 SPIE.Accession Number: 20180304654859 -
Record 459 of
Title:Ranging method based on linear frequency modulated laser
Author(s):Guo, Na(1,2); Gao, Cunxiao(1); Xue, Mingyuan(1,2); Niu, Linquan(1); Zhu, Shaolan(1); Feng, Li(1); He, Haodong(1); Cao, Zongying(1)Source: Laser Physics Volume: 27 Issue: 6 DOI: 10.1088/1555-6611/aa6da3 Published: June 2017Abstract:In this paper, we obtain target information about the distance between laser sources and targets based on the linear frequency modulated laser ranging system. We designed a specific experimental scheme for the ranging of linear frequency modulated semiconductor lasers based on heterodyne ranging experiment. Ranging precision can reach micron dimension and range resolution is about 0.002 m within the range of 1-40 m. The ranging method in this paper can apply to laser radars which could be used to capture target information, which is very helpful for tracking, identifying and extracting targets. ? 2017 Astro Ltd.Accession Number: 20172103691508 -
Record 460 of
Title:Design of inspection system for surface defects on industrial parts under complex background
Author(s):Wang, Yudan(1,2); Wen, Desheng(1); Song, Zongxi(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2282664 Published: 2017Abstract:This work aims at detecting defects on metallic industrial parts with complex surface. The searched defects are scar, rust and inclusion. A specific inspection system has been designed to deal with the particular inspected surface features. In the system, two images are acquired with the help of multiple light sources and CCD color digital camera. Based on the traditional algorithm, the background removal algorithm is designed in this article, and the color image feature extraction is also used for auxiliary analysis. A thresholding processing is then applied on this image in order to segment the imperfections. The perimeter and area of defects are calculated to further identifies the characteristics. The developed inspection system has been tested and it can accurately detect the defects of industrial parts with complex background. The recognition rate of algorithm is more than 96%. ? 2017 SPIE.Accession Number: 20180404671093 -
Record 461 of
Title:Improved automatic exposure algorithm for the stereoscopic panoramic camera in space application
Author(s):Wang, Jiali(1,2); Duan, Yongqiang(1); Zheng, Peiyun(1); Gao, Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2285786 Published: 2017Abstract:The automatic exposure algorithms have been successfully used in a variety of imaging platforms. However, most automatic exposure algorithms are not suitable for the application in space due to the complicated space environment, such as dramatically varying temperature and special space background. Additionally, the algorithms must be designed to adapt to the hardware platform with the limited storage capacity and real-Time capability. This paper proposes an improved automatic exposure algorithm for the special application scenario in space, which is suitable for the real-Time application of space panorama cameras. In this paper, a simulation experiment of the mean-based exposure algorithm is carried out. And the result shows that temperature change and deep dark background in space environment will cause the computation error. So we introduce the iterative calculation and automatic threshold segmentation method to improve the mean-based exposure algorithm. The improved algorithm is implemented using FPGA in standard hardware description language (VHDL), and a test platform to simulating deep space environment is built with a halogen lamp, a whiteboard and a temperature controlled tank in a dark room. The experiment results show that the exposure time almost unchanged when the dark background varies greatly (25% - 100%), which verifies that the effect of dark background is removed. And it can be demonstrated that the influence of temperature on the algorithm is decreased, which based on the experiment result that the exposure time decreases with increasing temperature (15°C to 70°C). ? 2017 SPIE.Accession Number: 20180404671057 -
Record 462 of
Title:Fast triangle star identification algorithm based on uncertain sign
Author(s):Wei, Xin(1,2); Wen, Desheng(1); Song, Zongxi(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2285591 Published: 2017Abstract:As a fine star-field identification algorithm, triangle algorithm is used far and wide currently, but there are some defects in triangle algorithm, such as low search efficiency and high mismatches probability. In allusion to these defects, a new triangle algorithm based on uncertain sign is presented. This algorithm extracted F and R features of star triangle, and then built a guidance characteristic catalogue which was searched by means of k-vector, promoting the search efficiency, moreover, in order to avoid the occurrence of mismatch, this algorithm would verify guide star triangle's auxiliary information if its uncertain sign is 1. Simulation shows that: compared to the traditional triangle algorithm, this algorithm has a couple of advantages, including the higher rate of correct star recognition, lower mismatches probability, and better real-Time adaptability and robustness. And this algorithm can reach 97% on identification rate when the position error is 2 pixels, and average identification time is 38.74ms; the traditional algorithm is 75% when the position error is 2 pixels, and average identification time is 187.26ms. ? 2017 SPIE.Accession Number: 20180404671048 -
Record 463 of
Title:A novel remote sensing image fusion scheme based on NSCT and Compressed Sensing
Author(s):Wan, Peng(1); Song, Zongxi(2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2285590 Published: 2017Abstract:In this letter, we propose a novel remote sensing image fusion method based on the non-subsampled contourlet transform and the compressed sensing (CS) theory.[2][3] Method First, the IHS transformation of the multispectral images is conducted to extract the I component. Secondly, the panchromatic image and the component intensity of the multispectral image are decomposed by NSCT. Then the NSCT coefficients of high and low frequency subbands are fused by different rules, respectively. For the high frequency subbands, the absolute maximum selection rule is used to integrate high-pass subbands; while the adaptive regional energy weighting rule is proposed to fuse low-pass subbands. The sparse coefficients are fused before being measured by Gaussian matrix. The fused image is accurately reconstructed by Compressive Sampling Matched Pursuit algorithm (CoSaMP). Some experiments are taken to investigate the performance of our proposed method, and the results prove its superiority to the counterparts. ? 2017 SPIE.Accession Number: 20180404671047 -
Record 464 of
Title:A star pattern identification algorithm based on wheel code feature
Author(s):Shao, Yuancheng(1,2); Gao, Wei(1); Song, Zongxi(1); Wei, Xin(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10462 Issue: DOI: 10.1117/12.2285784 Published: 2017Abstract:Pyramid algorithm and grid algorithm are typical algorithms for all-sky autonomous star identification, and it has advantages of high recognition rate, and fast in running. However their recognition rate decreases rapidly when the position noise, lost stars or fake stars exist in the star image. In order to improve the performance of star sensor, a new star identification algorithm based on star pattern of wheel code is proposed. The algorithm combines the main star and its surrounding neighbor stars to form the characteristic unit, and then constructs the corresponding code feature and the wheel feature respectively. In the process of star matching, the algorithm uses the code feature of the observation star as an index to Inquire storage address of the candidate navigation star, and then calculates the similarity of wheel feature between the candidate navigation star and the observation. Simulation shows that: compared to the grid algorithm, this algorithm has higher rate of correct star recognition and better robustness. When the position error is 1 pixel and 2 lost stars exist in star image, this algorithm can reach 98.4% on identification rate, while the grid algorithm is 94.6%, and the pyramid algorithm is 83.5%; when the position error is 1 pixel and 2 fake stars exist in star image, this algorithm can reach 98.6% on identification rate, while the grid algorithm is 92.3%, and the pyramid algorithm is 87.2%. ? 2017 SPIE.Accession Number: 20180404671056 -
Record 465 of
Title:Entangled-photons compressive ghost imaging based on spatial correlation of sensing matrix
Author(s):Liu, Dawei(1,2); Li, Lifei(1); Geng, Yixing(1); Kang, Yan(1,2); Zhang, Tongyi(1,2); Zhao, Wei(1,2); Dong, Weibin(3); Shi, Kunlin(3)Source: Optical Engineering Volume: 56 Issue: 12 DOI: 10.1117/1.OE.56.12.123108 Published: December 2017Abstract:Using the entangled photons generated by the spontaneous parametric down conversion as a light source, we demonstrate the first quantum ghost imaging system with a modified compressive sensing technique based on the spatial correlation of sensing matrix (SCCS). The ghost image is achieved at 16.27% sampling ratio of raster scanning and 0.65 photons/pixel at each measurement on average. Our results show that image quality and photon-utilization efficiency are remarkably enhanced in comparison with the traditional compressive imaging technique, due to the sensing matrix and noise-free measurement vector rebuilt by SCCS technique. It suggests the great potential of SCCS technique applied in quantum imaging and other quantum optics fields, such as quantum charactering and quantum state tomography to use the information loaded in each photon with high efficiency. ? 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20180304652589 -
Record 466 of
Title:Refractive index and temperature sensitivity characterization of excessively tilted fiber grating
Author(s):Yan, Z.(1,2,3); Sun, Q.(1); Wang, C.(2); Sun, Z.(2); Mou, C.(2,3); Zhou, K.(2,4); Liu, D.(1); Zhang, L.(2)Source: Optics Express Volume: 25 Issue: 4 DOI: 10.1364/OE.25.003336 Published: February 20, 2017Abstract:We have investigated experimentally and numerically the temperature and refractive index (RI) sensitivity characteristics of excessively tilted fiber gratings (Ex-TFGs) in detail. Both results have shown that the temperature and RI sensitivities of Ex-TFGs are mode order dependent. For temperature sensitivity, the higher order cladding mode of Ex- TFG exhibited lower temperature sensitivity, quantitatively, the temperature sensitivities of TM cladding modes at the resonance wavelength around 1550nm are 9pm/°C, 6.8pm/°C, 5.6pm/°C and, 4pm/°C for cladding mode 28th, 31st, 35th, 40th, respectively, indicating the overall temperature sensitivity of Ex-TFGs were lower than that of normal FBGs. The SRI sensing results have shown that the RI sensitivity of Ex-TFG at the special index value could be improved by choosing the cladding mode with effective index close to the refractive index of the detecting medium. The SRI sensitivities at the effective mode index were 2250nm/RIU at 1.408, 864nm/RIU at 1.395, 1536nm/RIU at 1.380 and 1360nm/RIU at 1.355, for the cladding mode of 28th, 31st, 35th, 43rd, respectively. The experimental results have also shown the SRI sensitivity of Ex-TFG was increasing with increasing of the resonance wavelength. ? 2017 Optical Society of America.Accession Number: 20170903384132 -
Record 467 of
Title:A method to measure the modulation transfer function of Bayer filter color camera
Author(s):Duan, Ya-Xuan(1,2); Liu, Shang-Kuo(1,2); Chen, Yong-Quan(1); Xue, Xun(1); Zhao, Jian-Ke(1); Gao, Li-Min(1)Source: Wuli Xuebao/Acta Physica Sinica Volume: 66 Issue: 7 DOI: 10.7498/aps.66.074204 Published: April 5, 2017Abstract:With the development of optoelectronic technologies, color cameras have been widely exploited in space remote sensing, earth observations from space, environmental monitoring, urban construction, and many other fields. Currently, most commercial color cameras use a single charge coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) sensor that has a Bayer color filter array (CFA) on its pixel surface to obtain red (R), green (G), or blue (B) samples. As a way of evaluating imaging quality, modulation transfer function (MTF) can provide a comprehensive and objective metric for camera imaging performance. In the conventional knife-edge method for color camera MTF measurement, a linear uniform sampling of the edge spread function (ESF) must be completed before a fast Fourier transform (FFT) can be applied. As the sampling rate becomes large, the number of pixel points on the line which is parallel to the knife-edge become less. So taking average of the pixel points to obtain ESF can be strongly affected by the noise of sensor. Therefore it is necessary to balance the influences of sampling rate and sensor noise on the MTF measurement, and the recommended sampling rate is 4-6. When the tilt angle of knife-edge has an error, the nonuniform sampling ESF can be obtained by the slanted knife-edge method. This leads to a variation in the results of the camera MTF on a spatial frequency scale and early cut-off. The best MTF results of camera can be obtained by rotating knife-edge, calculating MTF power under different tilt angles of knife-edge, and finding the maximum MTF power. And we propose an algorithm for Bayer filter color camera MTF measurement. The algorithm processing includes extracting R, G, B colors of knife-edge images; projection; differential operation; Hanning window filtration; FFT; correction; weighting combination of R, G, B colors MTF; MTF power calculation; optimal tilt angle of knife-edge estimation. To verify the accuracy of the proposed method, the weighting response factors of R, G, B colors are calibrated and an experimental setup for color camera MTF measurement is established. The knife-edge target is rotated in angle steps of 0.02°, and the MTF results are calculated under different tilt angles of knife-edge within ±0.1° surrounding the estimate position by the proposed algorithm. The maximum differences of MTF results between the proposed method and fringe target method are 0.061 (Nyquist frequency fc) and 0.043 (fc/2), respectively. The results show that by searching the optimal tilt angle of knife-edge, the effect of non-uniform sampling on MTF result of color camera can be eliminated. Compared with the conventional method, the proposed method is superior for the measurement of the super-sampled MTF of color camera. Meanwhile, this method can also be applied to MTF measurements of radiographic systems, such as X-ray imaging system and other systems. ? 2017 Chinese Physical Society.Accession Number: 20171803621522 -
Record 468 of
Title:Dim targets detection and tracking by self-adaptive segmentation and particle filter in starry images
Author(s):Deng, Wen-Kang(1,2); Song, Zong-Xi(1); Gao, Wei(1); Li, Fei-Peng(1,2); Qi, Yin-Long(1,2); Wang, Chen-Chen(1,2)Source: Journal of Applied Science and Engineering Volume: 20 Issue: 2 DOI: 10.6180/jase.2017.20.2.06 Published: 2017Abstract:An effective method for dim and small multi-targets detection and tracking through successive CCD images in complex starry background is put forward in this paper. Optical starry background images contain a lot of interference noise besides the moving targets. Firstly, self-adaptive threshold segmentation can play an important role in eliminating noise and improving detection rate. Furthermore, back neighborhood frame correlation (BNFC) is proposed to detect and locate the target, which is sheltered by bigger interfered stars. After detection framework acquiring the location of moving targets, particle filter which has nonlinear filtering feature is applied to track the trajectories for multi-targets in real-time. Experimental results show that by using the adaptive target detection and improved particle filter, the trajectories could be achieved at a relative low signal to noise ratio (SNR ≥ 3.5) in the case of multi-targets detection and tracking in real time. The method has good prospect for engineering application.Accession Number: 20173404076940