2010
2010
-
Record 85 of
Title:Design of instantaneous measurement system based on optical transition radiation
Author(s):Jiang, Xiaoguo(1); Dong, Xiaona(2); Wang, Yuan(1); Chen, Liangyi(2); Zhang, Kaizhi(1); Shi, Jinshui(1); Deng, Jianjun(1)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 22 Issue: 9 DOI: 10.3788/HPLPB20102209.2147 Published: September 2010Abstract:An optical transition radiation(OTR)-based measurement system has been designed to obtain the instantaneous beam divergence and spot size of Dragon-I linear induction accelerator(LIA) simultaneously. It can achieve instantaneous mea-surement within about 10 ns, and provides an on-line instantaneous beam diagnostic method for a 18.5 MeV, 2 kA, 90 ns electron pulse. The typical results of beam spot and beam divergence are about 9 mm and 10.5 mrad. This system lays a foundation for the study of time-resolved beam diagnostic technique which will be adopted in Dragon-I LIA.Accession Number: 20104113283127 -
Record 86 of
Title:Effect of screen-electrode structures on MCP imager vacuum-gap discharge
Author(s):Cao, Zhurong(1); Yang, Zhenghua(1); Bai, Xiaohong(2); Zhang, Haiying(1); Liu, Shenye(1); Ding, Yongkun(1)Source: Qiangjiguang Yu Lizishu/High Power Laser and Particle Beams Volume: 22 Issue: 6 DOI: 10.3788/HPLPB20102206.1251 Published: June 2010Abstract:The vacuum-gap discharge damage of micro-channel plate(MCP) imagers based on two screen-electrode structures, with Al-screen and indium-tin-oxide(ITO) screen respectively, is investigated after first arcing. The results show that the erosion pattern of Al-screen MCP imager appears as crater, and the electric insulating strength is less than 3 kV/mm under 10 μs-wide screen voltage, independent of MCP. The erosion of ITO-screen mostly appears as phosphor transporting to MCP, which drives field emission to steady state, and the electric insulating strength can reach 9 kV/mm at 10 μs-wide voltage. Thus, the discharge of MCP imagers depends mostly on screen-electrode structure, and ITO-screen MCP imagers can obtain higher electric insulating strength.Accession Number: 20102713051246 -
Record 87 of
Title:Approximate analytical optical transfer function for a wavefront-coded imaging system with two-dimensional rectangularly separable phase masks
Author(s):Zhao, Hui(1); Li, Yingcai(1)Source: Optical Engineering Volume: 49 Issue: 9 DOI: 10.1117/1.3485759 Published: September 2010Abstract:Wavefront coding can be used to extend the depth of field of incoherent imaging systems and is a powerful system-level technique. In order to assess the performance of a wavefront-coded imaging system, defocused optical transfer function (OTF) is the metric frequently used. Unfortunately, to the best of our knowledge, among all types of phase masks, it is usually difficult to obtain the analytical OTF except the cubic one. Although numerical computation seems good enough for performance evaluation, the approximate analytical OTF is still indispensable because it can reflect the relationship between mask parameters and system frequency response in a clearer way. Thus, a method is proposed to derive the approximate analytical OTF for two-dimensional rectangularly separable phase masks. The analytical results are well consistent with the direct numerical computations, but the proposed method can be accepted only from engineering point of view and needs rigorous proof in future. ? 2010 SPIE.Accession Number: 20114714538274 -
Record 88 of
Title:Theodolite self-stabilization tracking servo system based on mobile platform
Author(s):Wang, Chen(1); Ma, Caiwen(1); Hao, Wei(1); Tian, Guangyuan(1)Source: Proceedings - 2nd IEEE International Conference on Advanced Computer Control, ICACC 2010 Volume: 1 Issue: DOI: 10.1109/ICACC.2010.5487052 Published: 2010Abstract:In order to improve the tracking and positioning accuracy of theodolite self-stabilization tracking based on mobile platform, the position of object is transformed from platform coordinate system to earth coordinate system by using coordinate axis circumrotation. A method of forecast tracking technique based on mobile platform is presented. The former compound angle is transform from platform coordinate to earth coordinate. The next compound angle is forecasted in earth coordinate, finally the forecast result is transform to the platform coordinate. The stable tracking technique based on mobile platform is realized. This forecast result is compared with direct forecast in platform coordinate. Tracking and positioning accuracy can be enhanced from 5′ to 1.5′,which fully prove that this forecast technique is more accurate and propitious to realize stable tracking on mobile platform. ? 2010 IEEE.Accession Number: 20104213306296 -
Record 89 of
Title:Invariants combination and optimization on aircraft recognition
Author(s):Zhu, Xufeng(1,2); Ma, Caiwen(1)Source: Journal of Information and Computational Science Volume: 7 Issue: 14 DOI: Published: December 2010Abstract:Controlling the stability of image invariants at every stage is proposed for extracting and selecting combined invariants. First, four stages on aircraft image recognition is discussed. Second, the benefits and shortages of four kinds of invariants, which include Hu's moments, Affine moments, Normalized Moment of Inertia and Normalized Fourier Descriptors, are analyzed. Third, multiple images for different aircraft types under various small space angles are collected and the above four invariants from these images are extracted. Fourth, the invariants are combined based on these four kinds of invariants and are optimized a new combined-invariants, which are sent to support vector machine classifier for identifying aircraft types. At last, the experiment results are shown that the recognition rate will be improved more apparently by using the optimized combined-invariants than by using the direct combined-invariants or single kind of invariants. Copyright ? 2010 Binary Information Press.Accession Number: 20111413890818 -
Record 90 of
Title:A digital pulse drive circuit for continuously modulated semiconductor laser
Author(s):Song, Zhi-Yuan(1,2); Feng, Li(1); Zhu, Shao-Lan(1,2); Niu, Lin-Quan(1,2)Source: Proceedings - 2nd International Conference on Information Technology and Computer Science, ITCS 2010 Volume: Issue: DOI: 10.1109/ITCS.2010.66 Published: 2010Abstract:A digital designing way of laser drive circuit for continuously modulate the frequency, pulse width and amplitude of the output of semiconductor laser has been demonstrated. Complex programmable logic device (CPLD) was utilized to generate square waves with tunable frequency, the accurate delaying chip and logic circuit which are digital controlled were used to generate electrical pulses with adjustable pulse width. The pulses were amplified by the laser diode driver. The maximum output current of the driver can be up to 600 mA. When the signal was used to drive the semiconductor laser, the shape of the pulses generated by the laser is identical with the electrical pulses. The repetition rate and pulse width of the laser pulse can be continuously adjustable from 1 to 10 kHz and 3 to 20 ns, respectively. Furthermore, the time of rising and falling edges for the laser pulse were less than 2 ns. ? 2010 IEEE.Accession Number: 20104213306917 -
Record 91 of
Title:Design of a color image fusion system based on DSP and FPGA
Author(s):Liu, Zhaohui(1); Wang, Yubing(1,2); Liu, Wen(1)Source: Proceedings - 2010 3rd International Congress on Image and Signal Processing, CISP 2010 Volume: 2 Issue: DOI: 10.1109/CISP.2010.5646714 Published: 2010Abstract:In this paper, a color image fusion system based on DSP and FPGA is introduced .In the system, TMS320DM642 is used as the kernel processor to finish the image's fusion arithmetic, storage and display. FPGA, which has the ability to control the logic of image capturing, is used as the assistive processor. The experiment shows that this technology can obtain color fusion image. ?2010 IEEE.Accession Number: 20105213529816 -
Record 92 of
Title:Simultaneous otdm demultiplexing and data format conversion using a D flip-flop
Author(s):Xie, Yiyuan(1); Zhang, Jianguo(2,3); Xu, Jiang(4)Source: Microwave and Optical Technology Letters Volume: 52 Issue: 2 DOI: 10.1002/mop.24955 Published: February 2010Abstract:A D flip-flop is used to simultaneously demultiplex and data format conversion a single 10 Gbits/s channel from a 20 Gbits/s optical time-division multiplexed data stream. Error-free demultiplexing was achieved at very low optical signal power: -14 dBm (20 Gbits/s). The proposed demultiplexer has a simple structure and achieves return-to-zero (RZ) to nonreturn-to-zero (NRZ) data format conversion. The demultiplexer allows monolithic integration. The proposed demultiplexer will become an important interface technology in future for connecting the ultra-fast optical time division multiplexing (OTDM) long haul networks to the wavelength division multiplexing (WDM) access and metro networks. ? 2009 Wiley Periodicals, Inc.Accession Number: 20100112616297 -
Record 93 of
Title:Stability analysis of on-board calibration system of spatially modulated imaging Fourier transform spectrometer
Author(s):Gao, Jing(1,2); Ji, Zhong-Ying(1); Wang, Zhong-Hou(1); Cui, Yan(1,2)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 30 Issue: 4 DOI: 10.3964/j.issn.1000-0593(2010)04-1013-05 Published: April 2010Abstract:Spatially modulated imaging Fourier transform spectrometer (SMIFTS) was an instrument that depended on interference, and after calibration, the reconstruction spectrum can quantificationally reflect the diffuse reflection of target under sunshine. On-board calibration of SMIFTS confirmed the change of SMIFTS according to relative spectrum calibration, inspected long-time attenuation of SMIFTS optical system, and corrected export data of SMIFTS. According to the requirement of remote sensor application, it must stay in vacuum environment for a long time. As a radiant standard, the stability of lamp-house in long time is the most important characteristic of on-board calibration system. By calculation and experimentation, analyses of on-board calibration of SMIFTS, and testing spaceflight environment characteristic of on-board calibration, the difficulty in the key parts of on-board calibration of SMIFTS such as lamp-house, spectrum filter and integrating sphere was solved. According to the radiation-time stability testing for lamp-house and optics, particle-radiation testing, environmental-mechanics testing and hot vacuum examination, good result was obtained. By whole-aperture and part-field comparative wavelength calibration, the spectrum curve and before-launch interferogram were obtained. After comparison with reconstruction spectrum under different condition, the stability and credibility of SMIFTS on-board calibration system was proved.Accession Number: 20101912918375 -
Record 94 of
Title:Optical system design of visible camera for space target detection
Author(s):Chang, Lingying(1,2); Zhao, Baochang(1); Wen, Desheng(1); Chen, Rongli(1); Ma, Zhen(1,2); Yao, Dawei(1)Source: Zhongguo Jiguang/Chinese Journal of Lasers Volume: 37 Issue: SUPPL. 1 DOI: 10.3788/CJL20103701.0136 Published: November 2010Abstract:In order to realize the detection of dark and weak target in space, the optical system of visible light detection camera with a large aperture is designed. Its effective focal length is 350 mm, F-number is 1/1.6, field of view is 3.2°, and working wavelength ranges from 450 to 950 nm. The structure of the visible light detection camera is described, and the structure form is determined to be Maksutov's two reflection system whose primary and secondary mirrors are spherical. CODE-V optical design software was used to iptimize the optical system. The image quality evaluation and thermal analysis result are presented. The result shows that each field spot diagram is nearly circular, 80% energy encircled is within the spot diameter of 26 μm, maximum distortion is less than 0.05% and lateral color is less than 5 μm, which meet the requirement of detection.Accession Number: 20105013489847 -
Record 95 of
Title:Design of new-style unobscured three-mirror optical system
Author(s):Guo, Yongxiang(1,2); Li, Yingcai(1); Lü, Baobin(1,2); Bai, Yu(1,2); Sun, Qibing(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 4 DOI: 10.3788/AOS20103004.1144 Published: April 2010Abstract:One new-style unobscured three-mirror optical system was designed, which was based on the Gregorian system. The design step of this special three-mirror optical system was analyzed, and then a system with effective focal length of 900 mm, field of view of 0.8°×0.8° and F-number of 9 was designed. Its total length is 330 mm. The image qualities of the example are near diffraction limit. The system has advantages of shorter physical size and better ability in restraining stray lights. Compare with other three-mirror optical systems, the most prominent advantage of this special three-mirror optical system is that it just uses two aspheric mirrors and one spherical, thus reducing the cost and the manufacturing difficulties a lot.Accession Number: 20102112958578 -
Record 96 of
Title:A compression algorithm of AT-3DSPIHT for LASIS's hyperspectral image
Author(s):Ma, Dongmei(1,2); Ma, Caiwen(1); Luo, Cuihua(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 2 DOI: 10.3788/AOS20103002.0378 Published: February 2010Abstract:A compression algorithm of asymmetric 3D set partitioning in hierarchical trees (AT-3DSPIHT) supporting region of interest (ROI) is proposed for imaging characteristics of large-aperture static imaging spectrometer (LASIS). Firstly, the hyperspectral image sequences are decomposed with asymmetric 3D discrete wavelet transform (3D-DWT). Secondly, different coding precisions are assigned to wavelet coefficients in different regions by the method of ROI to protect the hyperspectral information. Finally, the transformed images are encoded with the adapted 3D set partitioning in hierarchical trees (3DSPIHT) algorithm. The experimental results show that the peak signal-to-noise ratio (PSNR) is more than 40 dB at 8:1 compression rate, and the efficient protection of hyperspectral information is achieved.Accession Number: 20101312808402