www,色.com,av下页在线伊人

2011

Record 361 of

Title:Stray light removing design and simulation of the three-mirror optical system used in field bias

Author(s):Yan, Peipei(1,2); Fan, Xuewu(1); Zou, Gangyi(1); Yang, Lihua(1,2); He, Jianwei(1,2)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 10 DOI: Published: October 2011
Abstract:The stray light properties of the three-mirror optical system used in field bias was analyzed and the basic design principles of the light shade and baffle vanes were presented, then the design of them was discussed. The principles of stray light eliminating and evaluation using computer simulation technology were put forward. Considering that the system had a special rectangular field of view, and the field was off-axis in y direction, a certain demand on the external lens hood was proposed. So boxshaped outer wall combined with the cone-shaped wall was designed. The window shades were designed to be square and laid gradient by CAD modeling. Then, the system model was built in the Tracepro stray light analysis software with wavelength λ=0.25μm in which the light was traced according to the sixteen off-axis angles between 0.5 and 80, at the azimuth angles of 0° and 90°. Finally the PST curves were given through the calculation. It shows that the PST curves are going down in general and reach 10-8 at off-axis angles of 25°. The coefficient of the stray light is 3.59%. It proves the feasibility of design of the stray light eliminating and the further application can be carried out.
Accession Number: 20114814570320
Record 362 of

Title:Design of hybrid refractive-diffractive star sensor optical system with small F-number

Author(s):Yan, Peipei(1,2); Fan, Xuewu(1); He, Jianwei(1,2)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 12 DOI: Published: December 2011
Abstract:Diffractive optical elements were used in optical system of star sensor, and a new kind of very high precision star sensor optical system with small F-number was designed. The system had an effective focal length of 90 mm, an F-Number of F/1.2, a field of view 2ω of 7°, and a working wavelength range of 0.45-0.85 μm. The system structure was simple. And the especial requirements of star sensor system about the dispersion spot diameter, energy concentration, distortion, lateral color etc. were all satisfied. Moreover, the environmental temperature analysis about this system was carried through. The analysis result indicated that the athermal and anti-defocus performances of the optical system of star sensor were enhanced while miniaturization and lightweight design was realized by using diffractive optical elements. This method puts forward new ideas for star sensor optical system design and has important reference significance and application value.
Accession Number: 20120714765570
Record 363 of

Title:Precise thermal control of CCD assembly of space optical remote sensor

Author(s):Yang, Wengang(1); Li, Yifan(2); He, Tianbing(1); Bai, Zhe(1); Zhang, Xianghui(1); Wang, Yinghao(1); Yu, Lei(2); Fu, Weichun(2); Li, Yingcai(1)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8321 Issue: DOI: 10.1117/12.904832 Published: 2011
Abstract:One of the most significant requirements driving CCD assemblies design is the operating temperature. In order to avoid unaccepted dark current, CCD need operate between 7°C and 15°C and temperature gradient across the focal plane should be not greater than 1.0°C. These requirements must be achieved by combining active and passive measures. This paper focuses on the precise thermal control design, analysis and test. Because CCD assemblies include focal electronics and movable precise focalizing parts, thermal control must utilize the integrated method to achieve compatible design. Largely using standard and well-proven technologies, this paper also points out some special techniques used. Based on finite difference method and transient energy equations, thermal model of CCD assemblies were built utilizing thermal software and solved for extreme cases. To validate the design, thermal balance test has been done. Analysis and test results have shown that CCD temperature can be controlled between 7.2°C and 13.5°C and temperature gradient was less than 0.5°C. These jobs could give some guidance and reference for the precise thermal control of CCD assembly of other space optical remote-sensor. ? 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
Accession Number: 20120114664493
Record 364 of

Title:Optical design of two-step zoom system under visible light for a certain theodolite

Author(s):Zhou, Ke(1); Yang, Jianfeng(2)
Source: ICEOE 2011 - 2011 International Conference on Electronics and Optoelectronics, Proceedings Volume: 3 Issue: DOI: 10.1109/ICEOE.2011.6013403 Published: 2011
Abstract:Starting from the application background and the detector parameters, this paper computed the optical and structural parameters of the system. The basic design idea is dividing a large-scale and complicated system into several modules and allocating the design requirements to each subsystem reasonably. Every optical subsystem is independent, for all of them have reached almost a high image quality, as well as they can correct the aberration caused by other parts of the system. Connected the subsystems together by using ZEMAX, there formed a practical optical system of photoelectric theodolite. In the visible band of light, the aperture is 450mm, the long focal length is 4000mm with its maximum field 2ω=26.0' while the short focal length is 2000mm with its maximum field 2ω=51.9'. The value of MTF at 50lp/mm in every field is higher than 0.6. The image quality of the system is close to diffractive limit. ? 2011 IEEE.
Accession Number: 20114014386518
Record 365 of

Title:Athermalization design of wide temperature range for hybrid refractive/diffractive infrared objective

Author(s):Chen, Xiao(1,2); Yang, Jianfeng(1); Ma, Xiaolong(1); Bai, Yu(1,2); He, Jike(3); He, Jianwei(1,2)
Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 1 DOI: Published: January 2011
Abstract:Hybrid refractive-diffractive design offers a new approach for athermalization design in wide temperature range. In this paper, the working wavelength was in 8-12 μm; the full field of view was 9.15°; the efficient focal length(EFL) was 100 mm; the relative aperture was 1:1.5; the total optical length was 128 mm and the back focal length(BFL) was 10.5 mm. The system was designed with three lenses and two kinds of material-Ge and ZnSe. It was made simple, low mass and high image quality by introducing diffraction surface and even aspheric surfaces. The evaluation of the system was given in the temperature range -80-160°C. The results show that the modulation transformation function (MTF) is near to 0.6 at the spatial frequency of 12.5 lp/mm which is near to the diffractive limitation. It is compatible with staring focal plane array which has a format of 320 × 240 and the pixel pitch of 40 μm.
Accession Number: 20111313874968
Record 366 of

Title:A 3D non-linear orientation prediction wavelet transform for interference hyperspectral images compression

Author(s):Wen, Jia(1,2); Ma, Caiwen(1); Shui, Penglang(1)
Source: Optics Communications Volume: 284 Issue: 7 DOI: 10.1016/j.optcom.2010.11.069 Published: April 1, 2011
Abstract:According to the characteristic of large aperture static interference imaging spectrometer (LASIS), a non-linear orientation prediction three-dimensional (3D) wavelet transform method is proposed in this paper on the basis of the 3D orientation prediction wavelet transform method proposed by Li, Ma and Wu in 2008 [1]. The method proposed in this paper still combines directional prediction into 3D lifting wavelet transformation, but compared with the 3D orientation prediction wavelet transform method, it made a breakthrough in the limitation that the orientation predicted must be a straight linear direction. The experimental results showed that this method improved the performance of wavelet obviously, especially on the LASIS image with quite severe and unstable directional characteristic as seen in the study of Ma and Ma (2009) [2]. Meanwhile, the characteristic of spectrum image recovered by the proposed method also possessed better performance. ? 2010 Elsevier B.V. All rights reserved.
Accession Number: 20110813682028
Record 367 of

Title:Orthogonal matching pursuit signal reconstruction based on improved genetic algorithm

Author(s):Wang, Guo-Fu(1,2); Zhang, Hai-Ru(1); Zhang, Fa-Quan(1); Xu, Ting(1)
Source: Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics Volume: 33 Issue: 5 DOI: 10.3969/j.issn.1001-506X.2011.05.02 Published: May 2011
Abstract:The core problem of compressed sensing theory is how to find an efficient and fast reconstruction algorithm. The existing reconstruction algorithms (such as orthogonal matching pursuit) have some defects: slow reconstruction, the reconstruction algorithm is carried out under a given number of iteration conditions, and the adaptation is reduced by this compulsory stop. An improved genetic algorithm (IGA) combining with orthogonal matching pursuit (OMP) algorithm is carried out to construct the reconstruction matrix. First, an improved genetic algorithm is used to select the current maximum redundancy column vector from the measurement matrix columns with an optimal chromosome method. Then subtract the part of columns with optimal chromosome from the measurement matrix, and repeat iteration until it meets the reconstruction accuracy. Simulation results show that, compared with the existing reconstruction algorithms under the same conditions, time-consuming of the algorithm reduces 5 s and the size of the measurement matrix reduces about 10%. This method can stop iteration adaptively under the condition of reconstruction signal with unknown sparseness.
Accession Number: 20112414064869
Record 368 of

Title:Some observations on plasma-assisted combustion enhancement using dielectric barrier discharges

Author(s):Tang, Jie(1); Zhao, Wei(1); Duan, Yixiang(1,2)
Source: Plasma Sources Science and Technology Volume: 20 Issue: 4 DOI: 10.1088/0963-0252/20/4/045009 Published: August 2011
Abstract:We explore an effective way to promote propane combustion by applying a plasma discharge for efficiency enhancement. A coaxial-cylinder, dielectric barrier discharge is used to activate propane and air before they are mixed with each other and ignited for combustion. The characteristics of the combustion flame are well studied and evaluated by varying various operational parameters. It is found that the combustion process can be enhanced by applying a plasma on either the propane or air stream, and the combustion stability is found to be somewhat sensitive to the lean burning conditions and confined to a relatively narrow operating window. The temperature and spectrum of the flame in the main combustion zone are investigated with a 4 W plasma in the on or off state. The main components are identified, and the possible physical and chemical reaction mechanisms are discussed. A comparative analysis of these spectra and temperatures obtained in the main flame suggests that the energy generated from the 4 W plasma is partially used to heat the reaction gases in the flame, and another part of the energy is used to increase the luminosity, especially for activation of air. We also observe that combustion of high flow rate propane and/or air requires more discharge energy density under certain conditions. A comparison of combustion enhancement through different activation methods in flame blowout tests shows that reactive species derived from activation of air play a more critical role in the blowout limit of propane combustion flame than those generated by activation of propane at low equivalence ratio and propane flow. ? 2011 IOP Publishing Ltd.
Accession Number: 20113314241580
Record 369 of

Title:Influence of defocusing on measurement accuracy of image motion of space camera

Author(s):Fan, Chao(1); Li, Yingcai(2); Fu, Hongliang(1); Yang, Tiejun(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 31 Issue: 10 DOI: 10.3788/AOS201131.1028002 Published: October 2011
Abstract:To research the influence of the defocusing of CCD on the measurement accuracy when using the joint transform correlator (JTC) to measure the image motion of space camera, the quadratic phase factor induced by defocusing is deduced based on the theory of Fresnel diffraction. Then the measurement error caused by defocusing is studied by emulation and experiment respectively for the JTC which is processed by using the method of power spectrum subtraction and binarization with threshold of zero. The results show that, the measurement error is not more than 10% when the defocusing amount is within 5% of the focal length of the Fourier lens, and the robustness is good; if the defocusing amount is increasing, the measurement error will nonlinearly increase observably. The results of the research can supply provide useful reference for the real-time and online measurement of image motion.
Accession Number: 20114914584047
Record 370 of

Title:The design and characteristics analysis of lunar based Two Axes gimbal with high reliability

Author(s):Huang, Jing(1,2); Liu, Zhao-Hui(2); Li, Zhi-Guo(1,2); Chang, Zhi-Yuan(2); Shi, Xin(3)
Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8196 Issue: DOI: 10.1117/12.899596 Published: 2011
Abstract:In order to meet the requirements of lunar based astronomical observation which includes three different observing modes: specific celestial body observations, calibration observations, sky surveys, the two Axes gimbal is designed to guarantee the telescope can point and listen to a exact point in the sky. Due to the harsh environment on the moon and space payload weight limit, based on lightweight design method, such as structure optimization and rational material selection, the weight of gimbal is greatly reduced without decrease of rigidity and strength. In addition, because of the usage of external rotor mechanism for vertical shaft, the system's first order mode along the emission direction is greatly improved. On the other hand, The shaft with one fixed end and another free end is adopted to reduce the deflection between its two larger span ends. Furthermore, the shaft stuck at both ends due to temperature changes on the moon is eliminated by rational determining the clearance of deep groove ball bearings. Experiments show that, the system's first order resonant frequency can reach 81HZ, and the mechanism works well from -25 °C to +60 °C without stuck phenomenon occured. So, because of the adoption of approaches mentioned above, the mechanism has good mechanical properties, such as high reliability and light weight. ? 2011 SPIE.
Accession Number: 20113614296259
Record 371 of

Title:Research on measurement method of image motion of space camera based on optical correlator

Author(s):Fan, Chao(1); Li, Yingcai(2); Fu, Hongliang(1); Liang, Yitao(1)
Source: Guangxue Xuebao/Acta Optica Sinica Volume: 31 Issue: 7 DOI: 10.3788/AOS201131.0712006 Published: July 2011
Abstract:To measure the sub-pixel image motion which is caused by satellite attitude instability or vibration, the optical joint transform correlator (JTC) is used, which is based on using the auxiliary plane CCD to record the image motion in the focal plane of the satellite camera. The principle of this method is described, and the experimental platform is built. The measurement performance of the JTC is researched. The results show that the JTC can measure the sub-pixel image motion of the space camera entirely, and the accuracy is not variable with the contents of the input images. The measurement error submits the normal distribution with the mean of zero, and the root mean square (RMS) error is no more than 0.12 pixel under the conspicuous level of 0.05. This can meet the operating requirement of the space camera completely.
Accession Number: 20113114199159
Record 372 of

Title:A new method of baffle design

Author(s):Mei, Chao(1,2); Zhou, Sizhong(1); Ma, Ming(1); Guo, Zhili(1); Zhao, Shimin(3)
Source: Procedia Engineering Volume: 15 Issue: DOI: 10.1016/j.proeng.2011.08.848 Published: 2011
Abstract:Nowadays, as the development of the level of the land observation technology constantly improved, the demanded of the image quality are increasing rise. There are so many possibility factors which may influences of the image quality, especially in the inferred optical system, the main reason of them is stray light. The baffle is the main element in the observe system which can inhibit the stray lights that comes from out side of the system. The paper will show you an new idea in baffle design, we put the block aura in an angle which is not 90 degree in conventional. The design can keeps the stray lights out of the system or been greatly absorbed on the condition of low absorption rate of the baffle. We will show you the evidences of calculation, and gave you the basis of the design. ? 2011 Published by Elsevier Ltd.
Accession Number: 20115214631558

首頁上一頁3132 33 34 35 下一頁尾頁