中国科学院机构知识库网格系统: 检索

浏览/检索结果: 共8条，第1-8条

帮助

条数/页：排序方式：
	Space camera dynamic image quality measurement and evaluation (EI CONFERENCE) 会议论文 OAI收割 3rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2011, January 6, 2011 - January 7, 2011, Shanghai, China 作者: Zhang X.; Zhang X.; Zhang X. 收藏 \| 浏览/下载：21/0 \| 提交时间：2013/03/25 By using analysis of the infinity image of the space camera we intend to obtain the curve of the dynamic modulation transfer function. We extract the pixel gray values at the image edge which distribute as a knife-edge function and make differential calculation and Fourier transformation of it and then we can obtain the dynamic MTF curve of the optical system. The value of the curve at the Nyquist frequency is the most important parameter that reflects the image quality. We add push-scanning imaging and environmental effects to the static MTF of space camera and compare the MTF value with the dynamic MTF at Nyquist frequency. The comparison result can help us verify the accuracy of the calculating results and the feasibility of our method. (2011) Trans Tech Publications.
	Design of reimaging F/1.0 long-wavelength infrared optical system (EI CONFERENCE) 会议论文 OAI收割 International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China 作者: Zhang X.; Zhang X.; Zhang X. 收藏 \| 浏览/下载：36/0 \| 提交时间：2013/03/25 A reimaging F/1.0 long-wavelength infrared optical system is proposed. The design has a flexible opto-mechanical layout. The design process is as follows. Firstly the catadioptric reimaging system consists of two reflecting mirrors and a relay lenses. Two reflecting mirrors make up of the first imaging system and are therefore free of chromatic aberrations while low dispersion lenses were used in the reimaging system so the optical system do not need achromatic design for a high image quality. Then to correct high-order aberrations resulting from large relative aperture more parameters need to be used with aspheric or diffractive surfaces due to modern optic technology development. Here aspheric is selected for easily manufacture. Finally the design is completed with the help of ZEMAX software. The effective focal length of the objective is 120mm and the field of view (FOV) is 4. The simulated final design shows adequate image quality and the modulation transfer function (MTF) is close to diffraction limit. The effect of the surrounding environmental temperature is analyzed using the concept of thermal defocusing and the thermal compensation is discussed. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).
	The application of diagnostic equipment in the Tokamak fusion reaction (EI CONFERENCE) 会议论文 OAI收割 2011 International Conference on Optical Instruments and Technology: Optical Systems and Modern Optoelectronic Instruments, November 6, 2011 - November 9, 2011, Beijing, China Zhang B.-S.; Chang J.; Gong X.-Z.; Gan J.-F.; Feng S.-L. 收藏 \| 浏览/下载：18/0 \| 提交时间：2013/03/25 This paper introduces the infrared optical system in the Tokamak fusion reaction device. In this optical system 3.the relay group lenses. This paper describes the decrease of the modulation transfer function (MTF) when the temperature changes and how to compensate the decrease of the MTF in order to maintain the image quality in a high level. As a result the traditional optical structure can't meet the requirements 2.the Cassegrain system the image quality of this optical system can reach the requirements when the temperature changes. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE). because the length of the infrared optical system in the Tokamak is very long. The design of optical system in the detection facility includes three parts:1.the combination of the concave aspheric mirror and flat mirror
	Modulation transfer function in seeker camera limits resulting from missile flutter caused by aerodynamic force (EI CONFERENCE) 会议论文 OAI收割 2010 2nd International Conference on Industrial Mechatronics and Automation, ICIMA 2010, May 30, 2010 - May 31, 2010, Wuhan, China 作者: Zhang X.; Zhang X.; Zhang X. 收藏 \| 浏览/下载：26/0 \| 提交时间：2013/03/25 The imaging quality of seeker in flight mode has been evaluated through analyzing the effects of missile flutter on optical modulation transfer function (MTF) of the optical system. Firstly the data of transverse vibration has been processed to eliminate the trend term caused by the trajectory then obtained the displacement with two times trapezoidal integration. For the side rotation the high frequency noise interference in the data has been filtered by using five-point moving average method. Took this model as the quivering rule between the object and the image and then analyzed the effects of the transverse vibration and the side rotation on imaging quality through MTF. By calculation the r.m.s value of the image motion caused by missile transverse vibration is 0.026mm and the side rotation angle is 0.0044 . Through the establishment of two modulation transfer functions (MTF) of image random vibration and linear vibration the results show that the image quality had declined and the effect of transverse vibration on image quality is obvious. Through improving the rigidity of the missile and selection of small focal length optical system and shorten the time of exposure can improve the imaging quality of the seeker. 2010 IEEE.
	Modulation transfer function measurement of sampled imaging systems in field test (EI CONFERENCE) 会议论文 OAI收割 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, April 26, 2010 - April 29, 2010, Dalian, China 作者: Yang L.; Zhang J.; Zhang J.; Zhang J.; Wang J. 收藏 \| 浏览/下载：29/0 \| 提交时间：2013/03/25 A digital mirror device (DMD) based light projector was developed as the target generator in modulation transfer function (MTF) measurement. In order to overcome the sampling-scene phase effect in MTF measurement of sampled imaging systems a method using random targets is introduced to yield a phase-averaged MTF. The main potential problem of implementing this method is the fact that the stationary assumption of the random targets may be vitiated in practical measurement especially in field test due to the ill condition. We provide an efficient model-independent way of analyzing and isolating the spectral contents arising from these additional contributions to MTF measurement. Algorithms with adaptive parameter selection were also developed for spectral estimation of the test image in order to overcome the challenge brought by the size limit of the test matrices for one certain field of view derived from the isoplantic region. The MTF measurement of a CCD video imager is used to demonstrate the measurement technique and illustrate the benefits over other methods. In order to validate the results comparisons have been made between MTF measurements of imager implemented using this method and bar target direct measurements. 2010 Copyright SPIE - The International Society for Optical Engineering.
	Optical system of large relative aperture and wide field using aspheric corrector for detecting (EI CONFERENCE) 会议论文 OAI收割 4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, November 19, 2008 - November 21, 2008, Chengdu, China 作者: Zhang J.; Zhang J.; Zhang J.; Wang J. 收藏 \| 浏览/下载：22/0 \| 提交时间：2013/03/25 The magnitude requirement of space target detecting determines that the image of detecting telescope should have several performances: small spots the wider field of view small 80% encircled energy diameter and good MTF(Modulation transfer function). So the aperture and field of view of optical system have some demands accordingly. The larger aperture the more extensive range which the telescope searches. Now most of ground telescopes whose apertures are from 500mm to 1000mm is on-axis optical system the more energy that telescope collects and higher magnitude the telescope detects so wide field of view becomes the most importance problem. To obtain large relative aperture and wide field of view the paper introduces a catadioptric telescope with small aperture aspheric refractive corrector whose conic surface will be used to remove the aberrations due to large relative aperture and wide field of view. As to the optical system there is only one aspheric refractive corrector and it is relatively easy for manufacturing because of its concave figure and normal material. The paper gives the example and optimizes this optical system with ZEMAX program. And then the paper provides a specific analysis program for testing the aspheric refractive corrector. The aperture of this optical system is 750mm and its relative aperture is 0.82 and the field of view is 3.6 diameter(diagonal). Its structure is simple and the image quality is also very good. 2009 SPIE.
	On orbit MTF measurement of remote sensing camera based on wavelet transform (EI CONFERENCE) 会议论文 OAI收割 ICO20: Remote Sensing and Infrared Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China 作者: Wang X.; Wang X.; Wang X. 收藏 \| 浏览/下载：18/0 \| 提交时间：2013/03/25 High resolution remote sensing images are often applied in many research fields. But there are less research on images quality for an orbit remote sensing camera. The magnitude of the OTF as the modulation transfer function (MTF) is a measure of the 2-D spatial frequency response of the remote sensing camera. In this paper knife-edge technique based on quadratic spline wavelet fast transform algorithm is proposed and applied to generate MTF with a greatly high resolution in horizontal or vertical direction. The result has fully demonstrate the potential applicability and good property of the method to estimate MTF for remote sensing camera.
	Geometrical modulation transfer function of different active pixel of CMOS APS (EI CONFERENCE) 会议论文 OAI收割 2nd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, November 2, 2005 - November 5, 2005, Zian, China 作者: Li J.; Liu J.; Liu J.; Liu J.; Li J. 收藏 \| 浏览/下载：25/0 \| 提交时间：2013/03/25 The geometrical Modulation Transfer Function (MTF) of CMOS APS (active pixel sensor) is analyzed in this paper. Advanced APS have been designed and fabricated where different pixel shapes such as square rectangle and L shape were placed because the amplifier circuit and other function circuits inter pixel of APS take up some pixel area. MTF is an important figure of merit in focal plane array imaging sensors. Research on analyzing the MTF for the proper pixel shape is currently in progress for a centroidal configuration of a target position. MTF will give us a more complete understanding of the tradeoffs opposed by the different pixel designs and by the signal processing conditions. Based on image sensor sampling and reconstructing model the MTF expression of any active pixel shape has been deduced in this paper. According to actual pixel shape three different active area pixels were analyzed they were square rectangle and L shape their Fill Factor (FF) is 30% 44% and 55% respectively. Results of simulation experiments indicate that different pixel geometrical characteristics contribute significantly to the figures of their MTF. Different geometrical shape of active sensitive area of pixel and different station in pixel would influence MTF figures. The analysis results are important in designing better APS pixel and more important in analyzing imaging system performance of APS subpixel precision system.