2010
2010
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Record 109 of
Title:Design of a four-mirror optical system with wide field of view
Author(s):Liang, Shi-Tong(1,2); Yang, Jian-Feng(1); Xue, Bin(1); Ruan, Ping(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 7849 Issue: DOI: 10.1117/12.871717 Published: 2010Abstract:Reflective optics is used widely in space optical systems for their achromatization, large aperture and lightweight compared with refractive systems. Four-mirror system especially off-axis system is desired for its excellent imaging performance and compact structure. Aberration theory of coaxial four-mirror system based on PW method is analyzed and the design procedure is proposed to get the initial four-mirror system in this paper. A large field off-axis four-mirror system is designed based on the theory and the design process. The system contains four conic aspheric mirrors. It has a 2°×0.32° rectangular field of view. The MTF of the system is diffraction-limited and the distortion is less than 0.1%. The structure of the system is compact and the ratio of total axis length to focal length is about 1/3.9. The excellent imaging performance and compact structure make it adaptable to space remote sensing systems. ? 2010 Copyright SPIE - The International Society for Optical Engineering.Accession Number: 20110113551089 -
Record 110 of
Title:An analytical investigation of excitonic absorption in terahertz-driven quantum wells
Author(s):Zhang, Tong-Yi(1); Zhao, Wei(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 7854 Issue: DOI: 10.1117/12.868775 Published: 2010Abstract:An analytical solution of the optical susceptibility of quantum wells driven by a terahertz (THz) field is achieved based on the density-matrix formalism. A simplified three-level model is adopted for the quantum well structures, with the levels coupled by a near-infrared (NIR) and a THz field. The equation of motion for the polarization is derived from Liouville's equation for the density matrix. Using Floquet's theorem, and under the rotating-wave approximation with respect to the NIR probe field, analytical expression for the optical susceptibility of the driven quantum wells is obtained. Different features rising induced by the driving THz field in the absorption spectrum of the NIR probe are discussed for the THz field near resonance and out of resonance of the intraexcitonic transition. This analytical investigation of the susceptibility of the THz-field-driven quantum wells is much useful for clearly identifying the physical principles obscured in the full numerical calculations. ? 2010 Copyright SPIE - The International Society for Optical Engineering.Accession Number: 20110213560531 -
Record 111 of
Title:Simple approach to picosecond pulse generation based on semiconductor optical amplifier
Author(s):Yan, S.Y.(1); Zhao, W.(1); Xie, X.P.(1); Lu, H.Q.(1)Source: Electronics Letters Volume: 46 Issue: 10 DOI: 10.1049/el.2010.0313 Published: May 13, 2010Abstract:A simple optical pulse generator based on a semiconductor optical amplifier (SOA) is demonstrated with an easy-generated external optical pulse sequence. Using the cross-gain modulation and self-phase modulation effects inside an SOA, the simple optical pulse generator generates a 10GHz 3.8ps optical pulse train with an extremely low timing jitter of 60fs. ? 2010 The Institution of Engineering and Technology.Accession Number: 20103313147371 -
Record 112 of
Title:Hybrid finite difference method and its application in micro-strip circuit analysis
Author(s):Wang, Shengyuan(1,3); Li, Yushan(2); Cao, Jianzhong(1)Source: Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument Volume: 31 Issue: 7 DOI: Published: July 2010Abstract:In this paper, the hybrid finite difference method is used in the analysis and design of micro-strip circuit. This method can deal with the issue that the difference between the spatial resolution and structure size of monolithic microwave integrated circuits (MMIC) needs to be considered. For the geometrical details, such as the edges of micro-strip line planar metal, the quasi-static field simulation is used to estimate the field and current distribution. Then the result is incorporated into the dynamic part of the hybrid method. This will maintain the accuracy of general finite difference method while reducing computational complexity. This method is applied to extract the effective dielectric constant of MMIC. The results of this method are compared with those of conventional finite-difference (FD) method. The two results agree well, which shows the efficiency of HFDM. This method is used to analyze actual micro-strip divider. Numerical results and measurement results demonstrate the accuracy of the proposed method.Accession Number: 20103413175008 -
Record 113 of
Title:Study of the radiation calibration of TDI-CCD spatial stereo camera
Author(s):Ren, Huanhuan(1,2); Ruan, Ping(1); He, Jianwei(1,2); Xue, Bin(1); Qiao, Weidong(1); Liang, Shitong(1,2); Wang, Hongwei(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 12 DOI: 10.3788/AOS20103012.3476 Published: December 2010Abstract:The principle of the radiation calibration of TDI-CCD spatial stereo camera is introduced in detail in three aspects of dark current data, relative calibration and absolute calibration. Then the process of the radiation calibration is briefly described. Finally the data measured during the calibration is disposed and analyzed. How the dark current is eliminated effectively and the method of the relative calibration in each condition is mainly illustrated. In order to effectively eliminate the dark current, a part of the direct current, two methods are compared. In the process of relative calibration, the calibration matrices are calculated after analyzing a huge number of data. And in the tolerance of the system, the most suitable matrix to any condition is optimized among many matrices. It is proved that the average deviation of any calibrated image is usually between 0.08 and 1.5 in gray value, and the maximum error is 2.80%. So the complexity of the calibrating process is decreased in the practical application, and the image processing in the later stage of the work is also simplified.Accession Number: 20111213768122 -
Record 114 of
Title:Full-wave analysis and rigorous design of new annular branch hybrid
Author(s):Wang, Sheng-Yuan(1,2); Li, Yu-Shan(3); Cao, Jian-Zhong(1)Source: Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (Engineering and Technology Edition) Volume: 40 Issue: 3 DOI: Published: May 2010Abstract:A new design method is proposed and used to analyze the characteristics of micro-strip discontinuities of a new type of annular branch hybrid. First, the even-and odd-mode theory is employed to analyze the ideally simplified circuit model and to obtain the preliminary circuit dimensions. Then, based on these dimensions, the Method of Moments (MoM) to the electric field integral equation together with the full space-domain Green's function is used to find the currents in the micro-strip circuits and the junction scattering parameters. All the physical effects are taken into consideration in this proposed approach. Numerical and experimental results of the new type of annular branch hybrid demonstrated the accuracy and efficiency of the proposed method.Accession Number: 20102312987657 -
Record 115 of
Title:Blind image restoration based on automatic blur identify and total variation minimization
Author(s):Su, Xiuqin(1,2); Li, Xiang(1,2); Ji, Lei(1,2)Source: 2010 International Conference on Mechanic Automation and Control Engineering, MACE2010 Volume: Issue: DOI: 10.1109/MACE.2010.5536517 Published: 2010Abstract:In this paper, an adaptive blind image restoration algorithm is proposed. According to the feature that the certain blur may lead to the specific component distortion in the cepstral domain, we develop an automatic algorithm using Fourier-Mellin transform to classify and identify the point spread function (PSF) with cepstrum: for the usual types of blur, such as linear motion blur and defocus blur, we restore it with Wiener filter; while for others, we propose an improved total variation (TV) blind restoration algorithm. The algorithm combines the typical methods and blind methods of image restoration, achieving the adaptive blind image restoration. Experimental results show that it is effective in restoring degraded images under different environments, and it improves the restoring performance significantly under the presence of high noise level. ?2010 IEEE.Accession Number: 20103513202122 -
Record 116 of
Title:Design of VISAR optical system for Shen-Guang-III prototype
Author(s):Yan, Ya-Dong(1); Zhang, Fa-Quan(2); He, Jun-Hua(1); Qi, Wen-Bo(1)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 18 Issue: 11 DOI: 10.3788/OPE.20101811.2355 Published: November 2010Abstract:To establish a Velocity Interferometer System for Any Reflector(VISAR) for the shock velocity measurement based on a laser Doppler shift effect, an optical system with a bandwidth of 0.2 nm was designed by using the 532 nm laser illumination. By choosing advisable materials, the fused silica was used in the optical system to improve the radiation resistance. Then, the second harmonics of the drive lasers and other stray lights are filtered by band-pass filters and laser line filters. To simplify the system assembly, the modularized design method and a optical gemel hinge were taken to compose models. Furthermore, the 532 nm laser was used for initially adjustment and the white light was used for accurately adjustment to implement the optical path difference to the zero. The proposed system show its total path length is 6.3 m, field of view is φ1.0 mm, and magnifications are 5× and 10×. A static experiment was undertaken, which can offer straight fringes and can give a static contrast above 0.67 and a resolution of 5.3 um. Moreover, a dynamic experiment of the system was carried out on the Shen-Guang laser-III facility successfully.Accession Number: 20105113512309 -
Record 117 of
Title:Effect of self-generated magnetic fields on fast-electron beam divergence in solid targets
Author(s):Yuan, X.H.(1,6); Robinson, A.P.L.(2); Quinn, M.N.(1); Carroll, D.C.(1); Borghesi, M.(3); Clarke, R.J.(2); Evans, R.G.(2,4); Fuchs, J.(5); Gallegos, P.(1,2); Lancia, L.(5); Neely, D.(2); Quinn, K.(3); Romagnani, L.(3); Sarri, G.(3); Wilson, P.A.(3); McKenna, P.(1)Source: New Journal of Physics Volume: 12 Issue: DOI: 10.1088/1367-2630/12/6/063018 Published: June 11, 2010Abstract:The collimating effect of self-generated magnetic fields on fast-electron transport in solid aluminium targets irradiated by ultra-intense, picosecond laser pulses is investigated in this study. As the target thickness is varied in the range of 25 μm to 1.4 mm, the maximum energies of protons accelerated from the rear surface are measured to infer changes in the fast-electron density and therefore the divergence of the fast-electron beam transported through the target. Purely ballistic spreading of the fast-electrons would result in a much faster decrease in the maximum proton energy with increasing target thickness than that measured. This implies that some degree of 'global' magnetic pinching of the fast-electrons occurs, particularly for thick (>400 μm) targets. Numerical simulations of electron transport are in good agreement with the experimental data and show that the pinching effect of the magnetic field in thin targets is significantly reduced due to disruption of the field growth by refluxing fast-electrons. ? IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.Accession Number: 20102513018259 -
Record 118 of
Title:Athermalization design of wide temperature range for hybrid refractive-diffractive objective in 8~12 μm
Author(s):Chen, Xiao(1,2); Yang, Jianfeng(1); Ma, Xiaolong(1); Bai, Yu(1,2); He, Jike(3); He, Jianwei(1,2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 7 DOI: 10.3788/AOS20103007.2089 Published: July 2010Abstract:A large relative aperture athermalized infrared optical system with wide field of view is introduced. The working wavelength is 8~12 μm; the full field of view is 40°; the effective focal length is 6 mm; the relative aperture is 1.25; the total optical length is 50 mm; and the back focal length (BFL) is 15 mm. It consists of a diffraction surface and two aspheric surfaces with a triplet structure, only using germanium and ZnSe. The system is simple, low mass and high image quality. The evaluation of the system is given in the temperature range of -80°C~200°C. The results show that the modulation transformation function (MTF) is near to 0.7 at the spatial frequency of 16 lp/mm and also near to the diffraction limit.Accession Number: 20103113111311 -
Record 119 of
Title:Design of multi-spectral adaptive spectrometer based on Hadamard transform
Author(s):Shao, Xiu-Juan(1,2); Hu, Bing-Liang(1); Yan, Peng(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 39 Issue: 5 DOI: Published: October 2010Abstract:Spectral characteristics can be used to reveal surface composition and then recognize the target. In this paper, the principles of Hadamard transform based multi-channel detection and imaging spectrometer were discussed. A Hadamard transform multi-spectral adaptive imaging spectrometer based on digital micro-mirror device (DMD) was designed and developed. The spectrum of the target used this imaging spectrometer in the experiment was successfully restored. Since each substance had its unique spectrum, the curve of spectrum recuperated form the experimental data could be used to distinguish the practical composition of the target. The spectrum curve obtained in the laboratory with the international standard spectrum curve were compared as well. The result shows that the average error of spectrum curve obtained in the laboratory compared with the international standard spectum is less than 4%.Accession Number: 20105113512528 -
Record 120 of
Title:Optical design of imaging spectrometer based on acousto-optic tunable filter
Author(s):Chang, Lingying(1,2); Zhao, Baochang(1); Qiu, Yuehong(1); Wen, Desheng(1); Ma, Xiaolong(1)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 30 Issue: 10 DOI: 10.3788/AOS20103010.3021 Published: October 2010Abstract:In order to acquire space, spectrum, and polarization information, the optical system which is applied to acousto-optic tunable filter(AOTF) imaging spectrometer is designed. The work principle of AOTF is described, then on the basis of instrument and system considerations, the optical parameters of the telescope and collimating optics are distributed reasonably. The optical design software CODE-V is used for the design, optimization and analysis of the optical system, and a refractive grating halfway along the crystal is used to simulate the effects of the AOTF. The +1 and -1 orthogonally polarized orders are produced by the AOTF at the same time. The whole system is achromatized from 400~900 nm using only three types of glass and imaging resolution excelled 32 lp/mm when the modulation transfer function (MTF) reaches 0.75.Accession Number: 20104613383573