2013
2013
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Record 277 of
Title:Numerical study on time response characteristics of InP/InGaAs/InP infrared photocathode
Author(s):Sun, Qiaoxia(1); Xu, Xiangyan(1); An, Yingbo(1); Cao, Xibin(1); Liu, Hulin(1); Tian, Jinshou(1); Dong, Gaiyun(1); Guo, Hui(2); Li, Yanhong(2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 42 Issue: 12 DOI: Published: December 2013Abstract:The time response characterisitics of InP/In0.53Ga0.47As/InP heterojunction infrared photocathode was studyed in this paper, such photocathode worked at transmission mode with a wide spectral response range from 1.0-1.7 μm. Under certain field-assisted bias voltage, the transmission characteristics of photo-excited electrons inside the phococathode were simulated. The results show that the response speed of the photocathode are accelerated with the increasing of the field-assisted bias voltage. While P-InGaAs photo-absorbing layer is thickened, the response speed gets slow. The response speed also gets slow when increasing the doping concentration of InGaAs photo-absorbing layer. When increasing the thickness and doping concentration of P-InP photoelectron-emitting layer, the respose time will be prolonged. Based on all these conclusions, the structure parameters and doping concentration of each layer were optimized. The optimization results show that when the thickness of the photo-absorbing layer and the photoelectron-emitting layer are about 2 μm and 0.5 μm respectively, and the doping concentration of photo-absorbing layer and photoelectron-emitting layer are about 1.5×1015 cm-3 and 1.0×1016 cm-3 respectively, the response time of photocathode can be reduced to less than 100 ps.Accession Number: 20140817349947 -
Record 278 of
Title:Analytical model of amplitude-weighted array technology in forming symmetrical radiation patterns
Author(s):Zhong, Lanxiang(1,2); Zhang, Zhiyong(1); Li, Jianlang(2)Source: Chinese Optics Letters Volume: 11 Issue: 8 DOI: 10.3788/COL201311.080102 Published: August 2013Abstract:A method on amplitude-weighted array technology is proposed based on an analytical formula in which the radiation amplitudes of array elements are evaluated analytically by a random symmetrical far-field radiation pattern. Using this formula, any desired spatial radiation pattern in the far field could be built by applying the analytical solutions of radiation amplitudes of array elements. To check the validity of this formula as well as the proposed technique, an annular intensity distribution as target far-field pattern is designed, and the respective radiation amplitude of array elements are determined by solving the formula analytically. The available far-field pattern is calculated by applying these solutions and then compared with the target far-field pattern. The theoretical results show the capabilities of the analytical derivation as well as the proposed technique in forming specific radiation patterns. ? 2013 Chinese Optics Letters.Accession Number: 20134917058249 -
Record 279 of
Title:Computational imaging technology for high-sensitivity space-image acquisition
Author(s):Sun, Jinqiu(1); Li, Haisen(1); Zhang, Haichao(1); Zhang, Yanning(1); Wen, Desheng(2)Source: Chinese Optics Letters Volume: 11 Issue: 11 DOI: 10.3788/COL201311.111101 Published: November 2013Abstract:Acquiring deep-space images with high spatial resolution and sensitivity is important for space-debris surveillance and early warning. We propose a novel computational imaging (CI) method for high-sensitivity image acquisition in this letter. The proposed approach introduces CI into image formation. The proposed capturing process conducts minor modifications for cameras to encode more desirable information during capture, which is practical for hardware implementation. The latent image is reconstructed by formulating a recovery problem into an optimization problem, which is solved with iteratively reweighted least square technique. The experimental results clearly show the effectiveness of the proposed method. ? 2013 Chinese Optics Letters.Accession Number: 20141017419575 -
Record 280 of
Title:An 90 degree airborne flex camera system
Author(s):Zhang, Jian(1); Yan, Aqi(1,2); Wang, Feng(2); Fan, Zheyan(1,2); Chen, WeiNing(1); Zhang, Zhi(1); Wu, Dengshan(1)Source: IEEE Region 10 Annual International Conference, Proceedings/TENCON Volume: Issue: DOI: 10.1109/TENCON.2013.6718913 Published: 2013Abstract:It is necessary to obtain high-speed dynamic image at a certain position outside an aircraft cabin such that we can monitor the state of the aircraft and measure some parameters quantitatively. We have to flex optical axis for 90 degree at mounting position. To solve long distance optical path conveying, improve imaging quality, and realize clear image at centre and other areas, secondary image is adopted when we design optical system. With the purpose of adapting to vibration and high-speed wind load on the aircraft, we adopt anti-mechanics and anti-wind load design. Finally, we test and verify the design by simulation and experiment. ? 2013 IEEE.Accession Number: 20140917393000 -
Record 281 of
Title:Optimal design of the laser communication optical system
Author(s):Yan, Peipei(1); She, Wenji(1); Zhang, Hengjin(1)Source: Advanced Optoelectronics for Energy and Environment, AOEE 2013 Volume: Issue: DOI: Published: 2013Abstract:A design of a laser communications optical system with high transmitting and receiving performance is given. Considering the decrease of transmitting power caused by the obscuration of secondary mirror in traditional optical antenna, the eccentric-pupil Cassegrain optical antenna is designed. It improves the efficiency of transmitting power of optical communication terminal effectively. The system only uses one beam steering mirror to perform platform jitter compensation, one detector to perform spatial acquisition and tracking function, and an optical feedback for point-ahead compensation. The reduction in design complexity can lead to reduced system cost and improved system reliability. ? OSA 2013.Accession Number: 20134717009744 -
Record 282 of
Title:LDFT-based watermarking resilient to local desynchronization attacks
Author(s):Tian, Huawei(1,2); Zhao, Yao(3); Ni, Rongrong(1,2); Qin, Lunming(1,2); Li, Xuelong(4)Source: IEEE Transactions on Cybernetics Volume: 43 Issue: 6 DOI: 10.1109/TCYB.2013.2245415 Published: December 2013Abstract:Up to now, a watermarking scheme that is robust against desynchronization attacks (DAs) is still a grand challenge. Most image watermarking resynchronization schemes in literature can survive individual global DAs (e.g., rotation, scaling, translation, and other affine transforms), but few are resilient to challenging cropping and local DAs. The main reason is that robust features for watermark synchronization are only globally invariable rather than locally invariable. In this paper, we present a blind image watermarking resynchronization scheme against local transform attacks. First, we propose a new feature transform named local daisy feature transform (LDFT), which is not only globally but also locally invariable. Then, the binary space partitioning (BSP) tree is used to partition the geometrically invariant LDFT space. In the BSP tree, the location of each pixel is fixed under global transform, local transform, and cropping. Lastly, the watermarking sequence is embedded bit by bit into each leaf node of the BSP tree by using the logarithmic quantization index modulation watermarking embedding method. Simulation results show that the proposed watermarking scheme can survive numerous kinds of distortions, including common image-processing attacks, local and global DAs, and noninvertible cropping. ? 2013 IEEE.Accession Number: 20135117094997 -
Record 283 of
Title:Low-dose carbon-implanted planar waveguides in Er3+/Yb 3+ co-doped silicate glasses
Author(s):Liu, Chun-Xiao(1,2); Peng, Bo(2,3); Wei, Wei(2,3); Cheng, Shu(4); Li, Wei-Nan(2); Guo, Hai-Tao(2); Shen, Yuan(1)Source: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms Volume: 295 Issue: DOI: 10.1016/j.nimb.2012.11.010 Published: 2013Abstract:We report, for the first time to our knowledge, on the fabrication of planar waveguides in Er3+/Yb3+ co-doped silicate glasses by 6.0 MeV carbon implantation with a dose of 6.0 × 1014 ions/cm2. The guiding properties are measured by the prism-coupling and end-face coupling methods with a He-Ne beam. The refractive index profile of the planar waveguide is reconstructed by the reflectivity calculation method, which shows a typical "enhanced well + optical barrier" distribution. The micro-luminescence and Raman investigations reveal that the bulk features are not deteriorated significantly by the carbon implantation in the waveguide, exhibiting possible applications for integrated active photonic devices. ? 2012 Elsevier B.V. All rights reserved.Accession Number: 20130215877191 -
Record 284 of
Title:Research on the trends of photonic crystal polarization maintaining fibers
Author(s):Zhang, Chen-Yang(1,2); Shi, Teng-Fei(1,2)Source: Applied Mechanics and Materials Volume: 380-384 Issue: DOI: 10.4028/www.scientific.net/AMM.380-384.4391 Published: 2013Abstract:Based on a large number of domestic and foreign literatures, we Put forward that the global polarization maintaining structure PM-PCF is the future development trend. The PM-PCF preform manufacture and drawing process were detailedly analyzed and summarized in this paper. And the development difficulties of the PM-PCF were analyzed in-deep. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20134116829548 -
Record 285 of
Title:Development of the control circuits for the TID-CCD stereo camera of the Chang'E-2 satellite based on FPGAs
Author(s):Duan, Yong-Qiang(1,2); Gao, Wei(1); Qiao, Wei-Dong(1); Wen, De-Sheng(1); Zhao, Bao-Chang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8907 Issue: DOI: 10.1117/12.2034877 Published: 2013Abstract:The TDI-CCD Stereo Camera is the optical sensor on the Chang'E-2 (CE-2) satellite created for the Chinese Lunar Exploration Program. The camera was designed to acquire three-dimensional stereoscopic images of the lunar surface based upon three-line array photogrammetric theory. The primary objective of the camera is, (1) to obtain about 1-m pixel spatial resolution images of the preparative landing location from an ellipse orbit at an altitude of ～15km, and (2) to obtain about 7-m pixel spatial resolution global images of the Moon from a circular orbit at an altitude of ～100km. The focal plane of the camera is comprised of two TDI-CCDs. The control circuits of the camera are designed based on two SRAM-type FPGAs, XQR2V3000-4CG717. In this paper, a variable frequency control and multi-tap data readout technology for the TDI-CCD is presented, which is able to change the data processing capabilities according to the different orbit mode for the TDI-CCD stereo camera. By this way, the data rate of the camera is extremely reduced from 100Mbps to 25Mbps at high orbit mode, which is benefit to raise the reliability of the image transfer. The results of onboard flight validate that the proposed methodology is reasonable and reliable. ? 2013 Copyright SPIE.Accession Number: 20141317510224 -
Record 286 of
Title:A new system of high-precision absolute laser interferometer distance measurement
Author(s):Zhang, Chen-yang(1); Li, Bing(2)Source: Applied Mechanics and Materials Volume: 380-384 Issue: DOI: 10.4028/www.scientific.net/AMM.380-384.769 Published: 2013Abstract:With the improvement of precision in various fields, we present a new method for the measurement of the absolute distance of a remote target based on the laser interferometry technique. In this paper, we obtain the interference fringes change information (the distance information) with the help of laser scanning with different frequency. It does not require the target to move in the direction of measurement. We have done experiments to compare this new method's results with the results of RENISHAW interferometer. It's improved that the accuracy of distance measurement is 10-4~10-5 relatively. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20134116828728 -
Record 287 of
Title:Underwater optical imaging technology and its applications
Author(s):Zeng, Rong(1); He, Jun Hua(2); Lv, Pei(2)Source: Advanced Materials Research Volume: 710 Issue: DOI: 10.4028/www.scientific.net/AMR.710.408 Published: 2013Abstract:The applications of underwater optical imaging technology are reviewed. The main types of underwater laser imaging technology are introduced, such as underwater laser scanning imaging and underwater distance selected imaging. The respective imaging principle and characteristics are presented. Furthermore, the newest imaging technology, such as underwater compressive sensing imaging technology is described in detail. The recent researching status is included. ? (2013) Trans Tech Publications, Switzerland.Accession Number: 20133016530636 -
Record 288 of
Title:An adaptive two-point non-uniformity correction algorithm based on shutter and its implementation
Author(s):Wang, Huawei(1,2); Ma, Caiwen(1); Cao, Jianzhong(1); Zhang, Haifeng(1)Source: Proceedings - 2013 5th Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2013 Volume: Issue: DOI: 10.1109/ICMTMA.2013.51 Published: 2013Abstract:Because of the non-uniform response of infrared focal plane arrays (IRFPA), non-uniformity correction is a key technology in IRFPA application. The two-point correction algorithm is widely used in practical applications, but there are some disadvantages. The detector's response will drift with time and temperature, correction parameters will drift with this accordingly. In order to acquire good quality images, the correction parameters need to be recalibrated periodically. It is inconvenient for user. This paper proposed an adaptive non-uniformity correction algorithm based on the two-point correction, which can update the correction parameters automatically. And this paper else introduced the approach of the algorithm. Results showed that the algorithm is effective to compensate the response drift influenced by time and temperature. ? 2013 IEEE.Accession Number: 20131816286148