2014
2014
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Record 205 of
Title:Shaping algorithm for laser spot
Author(s):Wang, Feng(1,2); Luo, Jianjun(1); Li, Ming(2); Deng, Yue(2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 12 DOI: Published: December 25, 2014Abstract:In order to eliminate the backscattering phenomenon of the infrared laser sport images, or make the distribution of laser spot's gray levels reasonable, a backscattering suppression algorithm based on the spot center of gravity and an algorithm for compensating the gray levels of a laser spot were proposed. The backscattering suppression algorithm was based on extracting the laser spot's center of gravity. Then, the radius of the laser spot can be determined. Finally, the gray levels of the image should be decided by the set threshold. The algorithm for compensating the gray levels of the laser spot was based on determining the laser spot's edge points. Then, the center of the laser spot can be calculated. After that, the center should be corrected through the intensity of regional energy, and the radius of the laser spot would be confirmed. Finally, the gray levels of the laser spot were adjusted through the laser spot's center and radius. The experiment results of these two algorithms and their analyses were shown. Research proves that the backscattering suppression algorithm can substantially eliminate the backscattering phenomenon in the laser spot image, and the distribution of laser spot's gray levels is improved. The images which are processed by the algorithms are suitable for further analysis in engineering experiments or real-time observation. ?, 2014, Chinese Society of Astronautics. All right reserved.Accession Number: 20150300435793 -
Record 206 of
Title:Research on color constancy computation based on YCbCr color space and gray surface
Author(s):Wang, Hong(1,2); Yang, Jianfeng(1); Xue, Bin(1); Yan, Xingtao(1); Liang, Xiaofen(1,2)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9301 Issue: DOI: 10.1117/12.2070658 Published: 2014Abstract:Color constancy is of important for many computer vision applications, such as image classification, color object recognition, object tracking and so on. But unlike the human visual system, imaging device cannot be able to compute color constant descriptors which do not vary with the color of the illuminant, so solving color constancy problem is necessary. In the calculation of color constancy, illuminant estimation is the key. Because grey surfaces can perfectly reflect the color of the scene illumination, many methods have been proposed to identify grey surfaces to estimate the illuminant. But they either rely on the camera.s parameters, lacking universality, or work inaccurate in worse conditions. In order to solve these problems, in this paper, an iterative method is proposed. The quality of the proposed method is tested and compared to the previous color constancy methods on the Macbeth Chart and two data sets of synthetic and real images. Through MATLAB simulation, experimental pictures and quantitative data for performance evaluation were gotten. The simulated results show that the proposed algorithm is accurate and efficient in identification of the grey surfaces, even in worse condition. And it performs well in color constancy computation on both synthetic and real images. ? 2014 SPIE.Accession Number: 20150800551956 -
Record 207 of
Title:The precision analysis of continuous zoom lens in airborne electro-optical pod
Author(s):Yang, Xiao-Xu(1); Li, Da-Wei(1); Han, Jun-Feng(1); Dong, Qiang(1,2); Huang, Wei(1); Wei, Yu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9142 Issue: DOI: 10.1117/12.2054095 Published: 2014Abstract:In the research of electro-optical pod, this paper propose a mission requirements that continuous zoom lens system is using for measuring angle in the process. This paper analyzes the influence of angle measurement accuracy from focal length and optical axis errors in the process of continuous zoom, and given the mathematical model of the influence of angle measurement accuracy. The simulation analysis indicated that Angle measuring accuracy is affected by the process of continuous zoom. The simulation analysis results have certain instructive significance to engineering practice. ? 2014 Copyright SPIE.Accession Number: 20141217474341 -
Record 208 of
Title:Research on combined precision angle measurement theory of optical rotation platform
Author(s):Yuan, Hui(1,2); Liu, Zhao-Hui(1); Liang, Dong-Sheng(1,2); Liu, Fu-Cheng(1,2); Dong, Qiang(1,2)Source: Guangzi Xuebao/Acta Photonica Sinica Volume: 43 Issue: 11 DOI: 10.3788/gzxb20144311.1112003 Published: November 1, 2014Abstract:As the conventional angular measuring system which uses rotary encoders has the shortcomings of low resolution, large quantization noise and low angular velocity accuracy, a sensor fusion angle measurement method based on fiber optic gyroscope and rotary encoder was proposed. First, the encoder angle signal and the fiber optic gyro rate integration value were subtracted in a sliding window, and the rate drift of fiber optic gyroscope was estimated utilize least square method from the deviation signal. Secondly, the angle was estimated using the compensated angular velocity signal and the encoder signal through a certain combination algorithm. Finally, mathematical simulation and experimental verification were conducted for the proposed method. The results show that the simulation value and experimental value of angle measurement accuracy are improved from 1.2″ and 1.1″ to 0.17″ and 0.76″, respectively. The angular velocity measurement accuracy are also improved from 0.002°·s-1 to 0.001°·s-1. The proposed methed effectively improves the angle and angular velocity measurement accuracy, while avoiding the rate drift problem of fiber optic gyroscope. ?, 2014, Chinese Optical Society. All right reserved.Accession Number: 20144900301552 -
Record 209 of
Title:The camera lens design of 3D low light level color nightvision system
Author(s):Li, Juan(1,2); Liu, Zhao Hui(1); Mei, Chao(1,2)Source: Applied Mechanics and Materials Volume: 568-570 Issue: DOI: 10.4028/www.scientific.net/AMM.568-570.598 Published: 2014Abstract:Two camera lenses for 3D low light level color night vision systemare designed in CODE V. The panchromatic sensitive camera lens works in a widespectral band 400nm-1000nm, yellow green-sensitive camera lens works in a band of400nm-600nm.The two camera lenses have same parameters, such as focal length 120mm,relative aperture 1/2, the field angle of 5.26 °. In the design of two camera lenses,we split and complex cooke triplet lens, the chromatic aberration is balanced byadding a binary diffractive surface. The results of design show that sensitivepanchromatic camera lens and yellow-green-sensitive camera lens, in the all fieldof view, when the Nyquist frequency is 77.5 (lp / mm), all MTF is larger than 0.6;the axial chromatic aberration of sensitive panchromatic camera lens is 0.056mm.Two camera lenses have good imaging performance. ? (2014) Trans Tech Publications, Switzerland.Accession Number: 20142717908421 -
Record 210 of
Title:Dynamical focus position detection of single pulse high power laser system
Author(s):Zhao, Juanning(1,2); Dong, Xiaona(1); Da, Zhengshang(1); Li, Hongguang(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 6 DOI: Published: June 2014Abstract:To tackle the problem that traditional focus measure technologies cannot measure the focus shifting caused by thermal distortion in single pulse high power laser system, a system, composed with double vertical wedge groups producing array spots, can make instantly focus measure available. Two pairs of wedge -mirror groups which are placed vertically to each other are utilized as beam splitting system in this system. All those rays are finally detected by a detector, and formed a matric of spots with various sizes. Through single detection of spots matrix, various focus position shifts and the focus shifting measurement of the high power laser with single shot are obtained. After theoretical analyzing, software simulating and experiment testing, this technique has the advantages such as the adjustable detecting accuracy and range, good disperse quality, and the ability of restraining the effect of parasitic light.Accession Number: 20142917960091 -
Record 211 of
Title:Performance of diode-pumped Tm3+:Sc2SiO5 crystal passively Q-switched 2 μm laser
Author(s):Li, Yaqi(1); Liu, Jie(1,2); Zhu, Hongtong(1); Zheng, Lihe(3); Su, Liangbi(3); Xu, Jun(3); Wang, Yonggang(4)Source: Optics Communications Volume: 330 Issue: DOI: 10.1016/j.optcom.2014.05.049 Published: November 1, 2014Abstract:A diode-pumped passively Q-switched Tm3+:Sc2SiO 5 laser with a single-walled carbon nanotube saturable absorber is demonstrated for the first time. The maximum average output power of 189 mW has been achieved at 1970 nm under an absorbed pump power of 4 W. The minimum pulse width of 442 ns was obtained at a repetition rate of 55.6 kHz, corresponding to the highest peak power of 7.7 W and single pulse energy of 3.4 μJ, respectively. ? 2014 Elsevier B.V.Accession Number: 20142517835167 -
Record 212 of
Title:Optimal design of a new type space laser communication optical system
Author(s):Yan, Pei-Pei(1); Deng, Xiao-Guo(1); Li, Gang(1); Liu, Kai(1); Duan, Jing(1); Shan, Qiu-Sha(1); Jiang, Kai(1); Zhang, Yu(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 9521 Issue: DOI: 10.1117/12.2185077 Published: 2014Abstract:A design of a laser communications optical system with high transmitting and receiving performance is given. The traditional on-axis Cassegrain optical antenna has the default that the transmitting and receiving power decreased greatly because of the obscuration of the secondary mirror. Considering that the eccentric-pupil Cassegrain optical antenna is designed. The optical antenna system in transceiver has been designed by means of CODEV software. It improves the efficiency of transmitting and receiving power effectively. Its properties have been analyzed, such as gain, image quality, and transmission efficiency. Meanwhile, the materials of optical elements have been analyzed. The power decline curve has been obtained by means of the detailed analysis of antenna system in partial axis situation. The system includes transmitter channel, receiving channel and experiment channel. It can realize the functions of transmitter-receiver isolation and multi-light ways using dichroic mirrors and beam splitting prisms. The system volume and weight are reduced greatly. The complexity of conventional laser communication system is reduced enormously at the same time. It has important reference significance and application value. ? 2015 SPIE.Accession Number: 20151100647725 -
Record 213 of
Title:From heuristic optimization to dictionary learning: A review and comprehensive comparison of image denoising algorithms
Author(s):Shao, Ling(1); Yan, Ruomei(2); Li, Xuelong(3); Liu, Yan(4)Source: IEEE Transactions on Cybernetics Volume: 44 Issue: 7 DOI: 10.1109/TCYB.2013.2278548 Published: July 2014Abstract:Image denoising is a well explored topic in the field of image processing. In the past several decades, the progress made in image denoising has benefited from the improved modeling of natural images. In this paper, we introduce a new taxonomy based on image representations for a better understanding of state-of-the-art image denoising techniques. Within each category, several representative algorithms are selected for evaluation and comparison. The experimental results are discussed and analyzed to determine the overall advantages and disadvantages of each category. In general, the nonlocal methods within each category produce better denoising results than local ones. In addition, methods based on overcomplete representations using learned dictionaries perform better than others. The comprehensive study in this paper would serve as a good reference and stimulate new research ideas in image denoising. ? 2013 IEEE.Accession Number: 20142717881481 -
Record 214 of
Title:Aberration athermal design for infrared search and trace optical system
Author(s):Shen, Mande(1); Jiang, Qinxiu(1); Li, Cheng(1); Ren, Huanhuan(1); Chen, Liangyi(2)Source: Optik Volume: 125 Issue: 14 DOI: 10.1016/j.ijleo.2014.01.076 Published: July 2014Abstract:To satisfy environment requirement of infrared search and trace optical system, an infrared diffractive/refractive hybrid optical system in 3.7-4.8 μm with 11.42°of field of view for passive athermalization is presented. The system is consisted of three lenses, including two aspheric surfaces and a diffraction surface, which has only two materials Ge and Si. The optical system has compact structure, small volume and light weight. The image quality of the system approaches the diffraction limit in the temperature range -80 °C to 160°C. It is compatible with staring focal plane array which has a format of 320 × 240 and the pixel pitch of 30 μm. The system need not move the compensated lens repeatedly to obtain the best images from -80°C to 160°C and enhances the performance of target tracking and recognition. ? 2014 Elsevier GmbH. All rights reserved.Accession Number: 20142417824161 -
Record 215 of
Title:Space target sequence image simulation based on STK/matlab
Author(s):Liu, Fucheng(1,2); Liu, Zhaohui(1); Liu, Wen(1); Liang, Dongsheng(1,2); Yuan, Hui(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 43 Issue: 9 DOI: Published: September 25, 2014Abstract:A method for sequence image generation of dim point moving targets in complex star background was presented based on STK/matlab software. Firstly, the starry background modeling process was analyzed; then, the satellite disturbance and noise that affected the point target imaging were detailedly discussed to make sequence images simulated closer to the real world; and besides the space target was modeled and its relative geometric relationship with the observation satellite was predicted by the STK software, at the same time the visibility of high earth orbit was systematically analyzed. In addition, a simple and convenient method to calculate the space target visibility criterion was given. By taking into account of various factors that impacted the visibility of high earth orbit target, the space target orbit prediction data was generated by STK and then matlab software was adopted to simulate the sequence image. It's useful in providing space environment for detection and tracking space target.Accession Number: 20144400132265 -
Record 216 of
Title:Large-mode-area infrared guiding in ultrafast laser written waveguides in Sulfur-based chalcogenide glasses
Author(s):D'Amico, C.(1); Cheng, G.(1,2); Mauclair, C.(1); Troles, J.(3); Calvez, L.(3); Nazabal, V.(3); Caillaud, C.(3); Martin, G.(4); Arezki, B.(4); LeCoarer, E.(4); Kern, P.(4); Stoian, R.(1)Source: Optics Express Volume: 22 Issue: 11 DOI: 10.1364/OE.22.013091 Published: 41792Abstract:Current demands in astrophotonics impose advancing optical functions in infrared domains within embedded refractive index designs. We demonstrate concepts for large-mode-area guiding in ultrafast laser photowritten waveguides in bulk Sulfur-based chalcogenide glasses. If positive index contrasts are weak in As2S3, Ge doping increases the matrix rigidity and allows for high contrast (10?3) positive refractive index changes. Guiding with variable mode diameter and large-mode-area light transport is demonstrated up to 10μm spectral domain using transverse slit-shaped and evanescently-coupled multicore traces. ? 2014 Optical Society of America.Accession Number: 20142417813130