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2015

Record 61 of

Title:Analysis the influence of pyramidal error on the encoder accuracy test by using coordinate transformation

Author(s):Tian, Liude(1,2); Liu, Chaohui(1); Zhao, Jianke(1); Duan, Yaxuan(1,2); Pan, Liang(1); Zhao, Huaixue(1); Long, Jiangbo(1); Zhou, Yan(1); Li, Kun(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 5 DOI: 10.3788/AOS201535.0512003 Published: May 10, 2015
Abstract:In order to realize the high precision measurement of encoder accuracy, the principle and method to measure encoder accuracy by using polyhedron and autocollimator are introduced. The polyhedron coordinate system and autocollimator measurement coordinate system are established, and the precise mathematical model is established, which is relation with the measurement error of the encoder accuracy and pyramidal error. The simulation results show that the encoder shaft tilt angle and tilt direction will affect the measurement results of the encoder accuracy. Measurement error of encoder accuracy increases with encoder shaft tilt angle, and approximately proportional to the square. Measurement error of encoder accuracy changes with encoder shaft tilt direction. When encoder shaft tilt direction is 0° or 180°, measurement error is the smallest; When encoder shaft tilt direction is 90° or 270°, measurement error is the maximum. As encoder shaft tilt angle is 5′, the measurement errors can reach 0.11″~0.48″, which cannot be ignored for encoder with 1~3 levels of precision grade. Pyramidal error should be cotrolled in the appropriate range based on the precision grade of measured encoder. Specific requirements on pyramidal error are given for encoders with different precision grades. ?, 2015, Chinese Optical Society. All right reserved.
Accession Number: 20152600979189
Record 62 of

Title:Optical system design for infrared target simulator

Author(s):Song, Yansong(1,2); Yang, Jianfeng(1); Zhao, Yiyi(1,2); Yan, Xingtao(1); Ma, Xiaolong(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 4 DOI: 10.3788/AOS201535.0422007 Published: April 10, 2015
Abstract:A new common-path scheme for infrared target simulator is proposed in order to simplify the structure of infrared target simulator. Based on this scheme, a dual-channel infrared projection system with compacted structure is designed. The optical system is characterized by the system field angle of ±3°, the spectral band of 3~5 μm, the entrance pupil distance of 550 mm, the focal length of 220 mm and the F number of 3.67. After analyzing the reason why the structure of the previous infrared target simulator is complex and the influence of different forms of interference target simulator structure on the design of common-path system, a good solution is given with combination of blackbody source and scanning mirror as interference target source. Through theoretical study of the influence of scanning mirror on the system performance, the feasibility of this scheme is proved. The results show that the modulation transfer function of the main target channel is better than 0.5 at the field of 16lp/mm, the root mean square (RMS) radius of each channel is less than 18 μm, and the distortion is less than 1%. The system can meet the requirements of minus 10 ℃ to 40 ℃ working environment by focusing. ?, 2015, Chinese Optical Society. All right reserved.
Accession Number: 20152300916639
Record 63 of

Title:Analyzing time walk error of leading trailing edge CFD of timing discrimination for gaussian and rayleigh distribution waveform

Author(s):Dong, Lijun(1); Liu, Ke(1); Guo, Lei(1); Miao, Yinxiao(1); Xin, Liwei(2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9446 Issue: DOI: 10.1117/12.2181701 Published: 2015
Abstract:In this study we analyze one of a CFD for timing discrimination. Walk error, drift and precision are the three performance parameters of timing discrimination. The walk error is the most important error type generally. Firstly, we divided the waveform into two types. One is the Gaussian waveform distribution which has three parameters: Amplitude, mean, and the pulse width; and the other is Rayleigh waveform distribution which has two parameters: mean and pulse. We analyzed different situations with their changing parameter, and the drift value of time can be obtained for each parameter changing. ?2015 SPIE.
Accession Number: 20151200656431
Record 64 of

Title:Method for measuring laser spot center based on multi-dimensional reconstruction in integrated diagnostic system

Author(s):Wang, Zhengzhou(1,2,3); Hu, Bingliang(3); Yin, Qinye(2); Cao, Shikang(3); Li, Dongjian(3); Li, Hongguang(3)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 44 Issue: DOI: Published: December 25, 2015
Abstract:In order to enhance the weak and asymmetrical image of small laser spot and suppress the noise information, eliminate unstable laser spot effect on the calculation results, a new method was proposed in this paper. Firstly, a multi-dimensional image cube was constructed by many images captured in different time, the primary information was concentrated in the first dimensional image, the correlation of each dimensional image was removed. Secondly, the first dimensional image was divided into laser spot and background by Kmeans method, the classified image was processed by mathematical morphology, the edge of largest spot was searched as edge of small laser spot. Finally, the least square method of circle fitting was used to calculate small laser spot center. The experimental results show that the method can improve the accurate rate on checking the weak and asymmetrical laser spot, the binary laser spot area obtained by new method is 97.15% of ideal spot area, the error of small laser spot center and radius is less than 2 pixels, and realize the accuracy measure of small laser spot in the integrated diagnostic system. ? 2015, Editorial Board of Journal of Infrared and Laser Engineering. All right reserved.
Accession Number: 20160401852755
Record 65 of

Title:Filtering analysis on the random noise of fiber optic guroscope

Author(s):Tian, Yunpeng(1,2); Yang, Xiaojun(1); Guo, Yunzeng(1); Liu, Feng(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 9 DOI: 10.3788/AOS201535.0906006 Published: September 10, 2015
Abstract:The datum axis of high precision photoelectric steady tracking platform jittering and drifting slowly often makes the output signal of fiber optic gyroscope (FOG) contain random noise. Based on the characteristics mentioned above, time series analysis of the data actually measured from FOG which is actually applied in engineering is conducted. Noise model is established by using the recursive least squares method, and it is processed with adaptive Kalman filter. With an exhaustive analysis by using the Allan variance method, it is shown that the filtering effect of Kalman algorithm that simply adapts the observation noise covariance matrix R is much better than that of normal Kalman algorithm, and the real-time performance is better than that of the Saga-Huga adaptive Kalman algorithm. For the Kalman algorithm, the amount of calculation added is small. This work has some practical value to improve the performance of photoelectric stable tracking platform. ?, 2015, Chinese Optical Society. All right reserved.
Accession Number: 20154401475188
Record 66 of

Title:Athermalization design of collimating lens system for space solar telescope

Author(s):Tao, Shuaiyang(1,2); Yang, Jianfeng(1); Ma, Xiaolong(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9795 Issue: DOI: 10.1117/12.2207993 Published: 2015
Abstract:The Solar Magnetic Field Telescope (MFT) , which imaged directly towards the sun , received about 1000W heat load irradiating into the telescope system, resulting in changes of ambient temperature. According to the principles of athermal design, a collimating lens system was designed, allowing MFT to work properly between a wider temperature range . The collimating lens system with F number of 3.55, worked in the visible spectrum, had the effective focal length of 156.4mm and the full field of view of 2.8 arc min ×2.8 arc min. Through the passive optical athermal method , the optimized lens works at ambient temperature ranging from -40° to 60°.The radii of RMS are all smaller than the pixel pitch. The image quality approaches to diffraction limit and the MTF value is over 0.75, which satisfies the system specifications. ? 2015 SPIE.
Accession Number: 20161702279092
Record 67 of

Title:Galvanometer control system design of aerial camera motion compensation

Author(s):Qiao, Mingrui(1,2); Cao, Jianzhong(1); Wang, Huawei(1); Guo, Yunzeng(1); Hu, Changchang(1,2); Tang, Hong(1,2); Niu, Yuefeng(1,2)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9678 Issue: DOI: 10.1117/12.2197149 Published: 2015
Abstract:Aerial cameras exist the image motion on the flight. The image motion has seriously affected the image quality, making the image edge blurred and gray scale loss. According to the actual application situation, when high quality and high precision are required, the image motion compensation (IMC) should be adopted. This paper designs galvanometer control system of IMC. The voice coil motor as the actuator has a simple structure, fast dynamic response and high positioning accuracy. Double-loop feedback is also used. PI arithmetic and Hall sensors are used at the current feedback. Fuzzy-PID arithmetic and optical encoder are used at the speed feedback. Compared to conventional PID control arithmetic, the simulation results show that the control system has fast response and high control accuracy. ? 2015 SPIE.
Accession Number: 20161602271467
Record 68 of

Title:Technology research on image motion compensation of the rotating double optical wedge

Author(s):Zhao, Junli(1,2); Wu, Yiming(1,3); Gao, Limin(1); Zhang, Heng(3); Yin, Xunlong(3); Yao, Zhen(1,2)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 44 Issue: 5 DOI: Published: May 25, 2015
Abstract:Image blur dues to the relative motion with the target in the camera exposure time, it would be worse while the ratio of speed and height (or speed and distance) increased. At present, the optical image motion compensation method bases mainly on the reflective element. In order to overcome the disadvantages of complicated image rotation corrected mechanism, difficult position location and optical vibration occurred by the swing scanning, a new method based on rotating double optical wedge was proposed, the dynamic working matrix was built, the emergent light vector's trajectory was analyzed and simulated. According to the actual image motion compensation demand, the double optical wedge designing result and controlling method were presented. Through analysis and simulation, the results show that this method has significant advantages such as compact structure, easy controlling method, stable motion state, high compensation capacity, etc. It has very important practical value for the occasions of the greater ratio of speed and height (or speed and distance). ?, 2015, Chinese Society of Astronautics. All right reserved.
Accession Number: 20153501209530
Record 69 of

Title:Evolutionary compact embedding for large-scale image classification

Author(s):Liu, Li(1,2); Shao, Ling(1,2); Li, Xuelong(3)
Source: Information Sciences Volume: 316 Issue: DOI: 10.1016/j.ins.2014.06.030 Published: September 20, 2015
Abstract:Effective dimensionality reduction is a classical research area for many large-scale analysis tasks in computer vision. Several recent methods attempt to learn either graph embedding or binary hashing for fast and accurate applications. In this paper, we propose a novel framework to automatically learn the task-specific compact coding, called evolutionary compact embedding (ECE), which can be regarded as an optimization algorithm combining genetic programming (GP) and a boosting trick. As an evolutionary computation methodology, GP can solve problems inspired by natural evolution without any prior knowledge of the solutions. In our evolutionary architecture, each bit of ECE is iteratively computed using a binary classification function, which is generated through GP evolving by jointly minimizing its empirical risk with the AdaBoost strategy on a training set. We address this as greedy optimization leading to small Hamming distances for similar samples and large distances for dissimilar samples. We then evaluate ECE on four image datasets: USPS digital hand-writing, CMU PIE face, CIFAR-10 tiny image and SUN397 scene, showing the accurate and robust performance of our method for large-scale image classification. ? 2015 Elsevier Inc. All rights reserved.
Accession Number: 20143600019053
Record 70 of

Title:Sparse representation based on multiscale bilateral filter for infrared image using compressed sensing

Author(s):Han, Jiaojiao(1); Qin, Hanlin(1); Leng, Hanbing(2); Yan, Xiang(1); Li, Jia(1,3); Zhou, Huixin(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9674 Issue: DOI: 10.1117/12.2202706 Published: 2015
Abstract:Compressed sensing is an arisen and significant theory, which has been widely used in infrared image reconstruction and many methods based on compressed sensing have been proposed. However, the existing methods can hardly accurately reconstruct infrared images. Considering that the sparsity of an infrared image plays a crucial role in compressed sensing to accurately reconstruct image, this paper presents a new sparse representation (MBFSF) that integrates the multiscale bilateral filter with shearing filter to overcome the above disadvantage. Firstly, one approximation subband image and a series of detail subband images at different scales and directions are obtained by the MBFSF. Then, in view of the feature that the most information is preserved in the approximation subband image, the proposed method only measures the detail subband images and preserves the approximation subband image. Subsequently, a very sparse random measurement matrix is used for the measurement at the detail subband images to reduce the computation cost and storage of large random measurement matrices in compressed sensing. Finally, an accelerated iterative hard thresholding algorithm is employed to reconstruct the infrared image. Experimental results show that the proposed method has superior performance in terms of reconstruction accuracy and compares favorably with existing compressed sensing methods, which is an effective method in high-resolution infrared imaging based on compressed sensing. ? 2015 SPIE.
Accession Number: 20155201719066
Record 71 of

Title:Color filter array demosaicing: An adaptive progressive interpolation based on the edge type

Author(s):Dong, Qiqi(1,2); Liu, Zhaohui(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9675 Issue: DOI: 10.1117/12.2199330 Published: 2015
Abstract:Color filter array (CFA) is one of the key points for single-sensor digital cameras to produce color images. Bayer CFA is the most commonly used pattern. In this array structure, the sampling frequency of green is two times of red or blue, which is consistent with the sensitivity of human eyes to colors. However, each sensor pixel only samples one of three primary color values. To render a full-color image, an interpolation process, commonly referred to CFA demosaicing, is required to estimate the other two missing color values at each pixel. In this paper, we explore an adaptive progressive interpolation based on the edge type algorithm. The proposed demosaicing method consists of two successive steps: an interpolation step that estimates missing color values according to various edges and a post-processing step by iterative interpolation. ? Copyright 2015 SPIE.
Accession Number: 20161602266820
Record 72 of

Title:Error analysis of electro-absorption-modulator-based depth imaging system

Author(s):Zhang, Minrui(1,2); He, Zhengquan(1); Tian, Jinshou(1); Wang, Tao(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 35 Issue: 6 DOI: 10.3788/AOS201535.0611004 Published: June 10, 2015
Abstract:A numerical model of electro-absorption-modulator (EAM)-based time-of-flight depth system is established. A formula with scale factor is deduced to quantify the contribution of timing-error to the accuracy of system. Measurement error is studied with parameters of EAM as well as background noise and timing-error. The results show that with no timing-error the standard deviation of measurements is inversely proportional to the square root of the number of signal electrons and is proportional to the square root of the ratio of the number of background electrons to the number of signal electrons. System accuracy improved by employing EAM with high speed modulation and higher extinction ratio. With skew error increasing, measurement error rises rapidly and is difficult to be reduced by increasing the number of signal electrons in the well of sensor. The well capacity of sensor must be larger than 300 Ke and the skew error of signal must be less than ±200 ps if the accuracy of 7 m single depth image is required less than 1 cm. ?, 2015, Chinese Optical Society. All right reserved.
Accession Number: 20153601250959