2011
2011
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Record 85 of
Title:Improvement of the diffraction efficiency of isotropic and anisotropic gratings in fulgide film by auxiliary light
Author(s):Cheng, Ming(1,2,3,4); Menke, Neimule(1,2,3,4); Yao, Baoli(1,2,3,4); Wang, Yingli(1,2,3,4); Chen, Yi(1,2,3,4)Source: 2011 International Conference on Remote Sensing, Environment and Transportation Engineering, RSETE 2011 - Proceedings Volume: Issue: DOI: 10.1109/RSETE.2011.5965734 Published: 2011Abstract:No matter during the ordinary holograph recording process in photochromic media, or during the polarization holograph recording process in photoinduced anisotropy media, there exits an overshooting peak in the diffraction efficiency, which then decays to a lower permanent level or also to zero, because of the diminishing of fringe contrast caused by a photochemically active readout beam, unequal intensities of object and reference waves and the nonlinear saturation effects of photoisomerization process and photoinduced anisotropy process. It is known that in ordinary holograph recording, this decreasing process can be eliminated by illuminating the hologram with a uniform control beam that has the effect of molecular back-conversion photo chrome. It was found that in polarization holograph recording, this method also can be used. Experiments done with an ordinary hologram and a polarization hologram recorded in a bistable state photochromic 3-indolybenzylfulgimide/PMMA film at 633 nm have shown that a control beam at 405 nm can increase the stable-state diffraction efficiency, thus, allowing to decrease the rigorous requirements on the recording time, the object reference ratio and the reading beam intensity in the holographic recording. And the theoretical qualitative analyses are also given. ? 2011 IEEE.Accession Number: 20113614293300 -
Record 86 of
Title:A study on the buffeting aberrance regulation of TDICCD mapping camera
Author(s):Bai, Zhe(1,2); Ma, Zhen(1); Zhang, Boheng(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8194 Issue: DOI: 10.1117/12.900996 Published: 2011Abstract:In this paper, the fundamental of the TDICCD mapping camera is introduced, and the influence of the satellite buffeting on the image quality of the TDICCD camera is analyzed. In order to reduce the influence, a regulated resolution is put forward. Compared with the traditional TDICCD mapping camera, a special TDICCD focal plane which several TDICCD devices splited joint end to end is designed. A great deal of information are captured through the focal plane, and a mathematical model is established to analyze the data information. Then the results are feed back to the satellite, and the attitude of the satellite is actively regulated in real time. Finally, make experiments and simulation to validate it. The experiment result indicate that the design is valid. ? 2011 SPIE.Accession Number: 20113714325932 -
Record 87 of
Title:Fiber temperature sensor based on micro-mechanical membranes and optical interference structure
Author(s):Liu, Yueming(1); Tian, Weijian(1,2); Hua, Jing(1)Source: Journal of Physics: Conference Series Volume: 276 Issue: 1 DOI: 10.1088/1742-6596/276/1/012151 Published: 2011Abstract:A novel fiber temperature sensor is presented theoretically and experimentally in this paper. Its working principle is based on Optical Fabry-Perot interference structure that is formed between a polished optical fiber end and micro-mechanical Bi-layered membranes. When ambient temperature is varying, Bi-layered membranes will be deflected and the length of Fabry-Perot cavity will be changed correspondingly. By detecting the reflecting optical intensity from the Fabry-Perot cavity, the ambient temperature can be measured. Using finite element software ANSYS, the sensor structure was optimized based on optical Interference theory and Bi-layered membranes thermal expansion theory, and theoretical characteristics was simulated by computer software. In the end, using optical fiber 2×2 coupler and photo-electrical detector, the fabricated sample sensor was tested successfully by experiment that demonstrating above theoretical analysis and simulation results. This sensor has some favorable features, such as: micro size owing to its micro-mechanical structure, high sensitivity owing to its working Fabry-Perot interference cavity structure, and optical integration character by using optical fiber techniques.Accession Number: 20111513911278 -
Record 88 of
Title:An algorithm of spatial beamforming in far-field using amplitude weighting method
Author(s):Zhong, Lanxiang(1,2); Zhang, Zhiyong(1,2); Zhang, Wanxu(2)Source: Proceedings - 2011 7th International Conference on Natural Computation, ICNC 2011 Volume: 3 Issue: DOI: 10.1109/ICNC.2011.6022340 Published: 2011Abstract:Using amplitude weighting instead of phase shifting of radiation emitted by planar array, an algorithm for forming a specific radiation pattern in far-field was proposed, and the formula of calculating amplitude value was derived. As an example, in which the radiation energy was strained in a limited solid angle, the beamforming process was numerically analyzed, and it was finally indicated that the total number of elements can be determined by the ratio between the energy of main beam and amount of energy from all elements. ? 2011 IEEE.Accession Number: 20114014404534 -
Record 89 of
Title:Accelerating vehicle detection in low-altitude airborne urban video
Author(s):Cao, Xianbin(1); Lin, Renjun(1); Yan, Pingkun(2); Li, Xuelong(2)Source: Proceedings - 6th International Conference on Image and Graphics, ICIG 2011 Volume: Issue: DOI: 10.1109/ICIG.2011.93 Published: 2011Abstract:The limitation of the existing methods of traffic data collection is that they rely on techniques that are strictly local in nature. The airborne system in unmanned aircrafts provides the advantages of wider view angle and higher mobility. However, detecting vehicles in airborne videos is a challenging task because of the scene complexity and platform movement. Most of the techniques used in stationary platforms cannot perform well in this situation. A new and efficient method based on Bayes model is proposed in this paper. This method can be divided into two stages, attention focus extraction and vehicle classification. Experimental results demonstrated that, compared with other representative algorithms, our method obtained better performance with higher detection rate, lower false positive rate and faster detection speed. ? 2011 IEEE.Accession Number: 20113914362052 -
Record 90 of
Title:KLT feature based vehicle detection and tracking in airborne videos
Author(s):Cao, Xianbin(1); Lan, Jinhe(1); Yan, Pingkun(2); Li, Xuelong(2)Source: Proceedings - 6th International Conference on Image and Graphics, ICIG 2011 Volume: Issue: DOI: 10.1109/ICIG.2011.92 Published: 2011Abstract:Airborne vehicle detection and tracking systems equipped on unmanned aerial vehicles (UAVs) are difficult to develop because of factors like UAV motion, scene complexity and so on. In this paper, we propose a new framework of multi-motion layer analysis to detect and track moving vehicles in airborne platform. Moving vehicles are firstly detected by registration and temporal differencing to establish motion layers. After motion layers are constructed, they are maintained over time for tracking vehicles. All vehicles are tracked by maintaining their corresponding motion layers. Our experimental results showed that compared with other previous algorithms, our method can achieve better results in terms of detection and tracking performance. ? 2011 IEEE.Accession Number: 20113914362056 -
Record 91 of
Title:Current characteristic analysis of thermoelectric cooler
Author(s):Pan, Haijun(1,2); Ruan, Ping(2); Li, Fu(2); Wang, Hongwei(1,2)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 6 DOI: Published: June 2011Abstract:With the development of high performance cooling CCD imaging module in aerospace imaging detection, thermoelectric refrigeration is widely used for precision temperature control of electronic equipments as an effective active thermal control method. So the working current characteristic of thermoelectric cooler (TEC) was analyzed. Firstly, the operating modes of a TEM (thermoelectric module), such as cooling, heating and thermoelectric generation were introduced based on the analysis of the principle of thermoelectric refrigeration. Then, the temperature distribution in a thermocouple was analyzed under the first boundary condition. Finally, the influence of working current on the performance of thermoelectric refrigerator was analyzed, and the selection range of working current under cooling mode was obtained. The results show that the refrigeration effect can be decreased by too much or too little working current. Therefore these results have great value for the selection of working current of thermoelectric cooler.Accession Number: 20113114199247 -
Record 92 of
Title:New measurement method of the sub-pixel image motion based on optical correlator
Author(s):Yi, Hongwei(1); Li, Yingcai(1); Wen, Desheng(1); Li, Xuyang(1,2); Ma, Zhen(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 4 DOI: Published: April 2011Abstract:Joint transform correlator (JTC) is an effective way to measure the sub-pixel image motion which is caused by instability or vibration of satellite camera. The measurement accuracy is the key factor to determine its critical performance index. On the basis of the principle of image motion measurement with JTC, a method using a Fourier optical processor in combination with an electronic system to implement the function of the JTC was proposed. The upsampled version of a small region around cross-correlation peak was computed by digital processing unit, and the measurement accuracy of the cross-correlation peak was improved. The simulation test results show that, when upsampling factor k≥10, the measurement accuracy of 0.045 pixel can be achieved for 128 × 128 input image with SNR≥20 dB. Within 0-60 pixels displacement, the measurement accuracy can be controlled at about 0.05 pixel in different input scenes. The new method can improve the measurement performance effectively and reduce the complexity of the measurement system.Accession Number: 20112714112369 -
Record 93 of
Title:Confocal Fabry-Perot interferometer for frequency stabilization of laser
Author(s):Pan, H.-J.(1,2); Ruan, P.(1); Wang, H.-W.(1,2); Li, F.(1)Source: Laser Physics Volume: 21 Issue: 2 DOI: 10.1134/S1054660X11030170 Published: February 2011Abstract:The frequency shift of laser source of Doppler lidar is required in the range of a few megahertzs. To satisfy this demand, a confocal Fabry-Perot (F-P) interferometer was manufactured as the frequency standard for frequency stabilization. After analyzing and contrasting the center frequency shift of confocal Fabry-Perot interferometers that are made of three different types of material with the change of temperature, the zerodur material was selected to fabricate the interferometer, and the cavity mirrors were optically contacted onto the end of spacer. The confocal Fabry-Perot interferometer was situated within a double-walled chamber, and the change of temperature in the chamber was less than 0.01 K. The experimental results indicate that the free spectral range is 500 MHz, the full-width at half maximum is 3.33 MHz, and the finesse is 150. ? Pleiades Publishing, Ltd., 2011.Accession Number: 20110913706222 -
Record 94 of
Title:Design of catadioptric middle infrared continuous zoom lens for uncooled infrared detector
Author(s):Jiang, Kai(1); Zhou, Si-Zhong(1); Duan, Jing(1); Wang, Yan-Bin(1); Zhang, Heng-Jin(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8193 Issue: DOI: 10.1117/12.900193 Published: 2011Abstract:For uncooled 320x240 infrared detector, a catadioptric middle infrared continuous zoom lens is presented. The optical system is divided into three segments. First of all, a reflective system is designed as the front system. Then the continuous zoom lens which matches with the reflective system as the back system is designed. The conversed back system is assembled at the first imaging of the optical system with the reflective system. A continuous variable magnification catadiootric telescope is obtained. Projection objective is designed based on the telescope lastly. To ensure the imaging quality of the system, the whole system is optimized with the CODE V software. The system can realize 200mm～800mm continuous zoom. The designed result shows the system has the advantages of simple structure, short zoom path and smooth zoom locus, high image quality and approached or reached to the diffraction limit. ? 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).Accession Number: 20114114420333 -
Record 95 of
Title:Exploiting local coherent patterns for unsupervised feature ranking
Author(s):Huang, Qinghua(1); Tao, Dacheng(2); Li, Xuelong(3); Jin, Lianwen(1); Wei, Gang(1)Source: IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics Volume: 41 Issue: 6 DOI: 10.1109/TSMCB.2011.2151256 Published: December 2011Abstract:Prior to pattern recognition, feature selection is often used to identify relevant features and discard irrelevant ones for obtaining improved analysis results. In this paper, we aim to develop an unsupervised feature ranking algorithm that evaluates features using discovered local coherent patterns, which are known as biclusters. The biclusters (viewed as submatrices) are discovered from a data matrix. These submatrices are used for scoring relevant features from two aspects, i.e., the interdependence of features and the separability of instances. The features are thereby ranked with respect to their accumulated scores from the total discovered biclusters before the pattern classification. Experimental results show that this proposed method can yield comparable or even better performance in comparison with the well-known Fisher score, Laplacian score, and variance score using three UCI data sets, well improve the results of gene expression data analysis using gene ontology annotation, and finally demonstrate its advantage of unsupervised feature ranking for high-dimensional data. ? 2006 IEEE.Accession Number: 20114814561188 -
Record 96 of
Title:The hybrid refractive-diffractive optical system design of preposition of aperture LWIR
Author(s):Liu, Kai(1,2); Chen, Rongli(1)Source: ICEOE 2011 - 2011 International Conference on Electronics and Optoelectronics, Proceedings Volume: 3 Issue: DOI: 10.1109/ICEOE.2011.6013346 Published: 2011Abstract:The LWIR (Long Wave Infrared) used for observation heat. The influence of background radiation caused the sensitivity of the system decreased. The article uses subzero refrigeration detector, and require the efficiency of luminescence railing reaching 100%. The paper deduce the design formula of preposition of aperture LWIR, and the wave band 10～12μm, diameter 50mm, F/2, field 8.20×8.20. This paper based on the principle of binary diffractive optical elements, the unique dispersion properties have the incomparable advantage compared with traditional optical components in calibration system. Design results show that the hybrid refractive-diffractive Optical System compared with the traditional infrared optical system, not only use the fewer optical elements, and achieve the purpose of the lightweight, and the system performance also have significantly improved. ? 2011 IEEE.Accession Number: 20114014386461