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Advanced astigmatism-corrected tandem Wadsworth mounting for small-scale spectral broadband imaging spectrometer (EI CONFERENCE) 会议论文  OAI收割
作者:  Lin G.-Y.
收藏  |  浏览/下载：35/0  |  提交时间：2013/03/25
Tandem gratings of double-dispersion mount make it possible to design an imaging spectrometer for the weak light observation with high spatial resolution  high spectral resolution  and high optical transmission efficiency. The traditional tandem Wadsworth mounting is originally designed to match the coaxial telescope and large-scale imaging spectrometer. When it is used to connect the off-axis telescope such as off-axis parabolic mirror  it presents lower imaging quality than to connect the coaxial telescope. It may also introduce interference among the detector and the optical elements as it is applied to the short focal length and small-scale spectrometer in a close volume by satellite. An advanced tandem Wadsworth mounting has been investigated to deal with the situation. The Wadsworth astigmatism-corrected mounting condition for which is expressed as the distance between the second concave grating and the imaging plane is calculated. Then the optimum arrangement for the first plane grating and the second concave grating  which make the anterior Wadsworth condition fulfilling each wavelength  is analyzed by the geometric and first order differential calculation. These two arrangements comprise the advanced Wadsworth mounting condition. The spectral resolution has also been calculated by these conditions. An example designed by the optimum theory proves that the advanced tandem Wadsworth mounting performs excellently in spectral broadband. 2012 Optical Society of America.  
Study on ultra-light secondary baffle for coaxial two-mirror telescope (EI CONFERENCE) 会议论文  OAI收割
2012 9th IEEE International Conference on Mechatronics and Automation, ICMA 2012, August 5, 2012 - August 8, 2012, Chengdu, China
作者:  Zhang L.;  Zhang L.
收藏  |  浏览/下载：61/0  |  提交时间：2013/03/25
The coaxial two-mirror telescope consists of two mirrors facing each other. Classical two-mirror arrangements are Gregorian and Cassegrain. These systems are usually applied to space telescopes and often have optical baffles to prevent stray light from entering the focal plane. The optical baffles consist of concentric rings suspended between the secondary and the primary mirror. The secondary baffle for a large two-mirror optical system is designed and analyzed in this paper. According to mission of a telescope  the structure should have high stiffness and high reliability and light weight. Compared with invar  aluminum alloy and titanium alloy  carbon fiber composite is currently the best material in terms of weight-to-strength ratio. It also has advantages of high temperature tolerance and low thermal expansion. So carbon fiber composite is chosen as material to meet requirements of the coaxial telescope. In this paper  optimization method based on finite element analysis (FEA) is used for design the secondary baffle. Minimum weight of the baffle is chosen as an objective function. Thicknesses of former tube and vanes are chosen as variables. Analysis results show that the designed secondary baffle has maximum diameter of 180mm  total length of 120mm and weighs 142g. And its fundamental frequency reaches 651Hz. Therefore the baffle has many advantages  such as ultra-light weight  high stiffness and dimensional stability  etc. The optimization method and the baffle design can be helpful to other coaxial telescopes  such as Cassegrain  Gregorian and their subdivisions. 2012 IEEE.  
The research on statistical properties of TDI-CCD imaging noise (EI CONFERENCE) 会议论文  OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Imaging Detectors and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Gu Y.-Y.; Shen X.-H.; He G.-X.
收藏  |  浏览/下载：23/0  |  提交时间：2013/03/25
TDI-CCD can improve the sensitivity of space camera without any degradation of spatial resolution which is widely used in aerospace imaging devices. The article describes the basic working principle and application characteristics of TDI-CCD devices  analyses the composition of TDI-CCD imaging noise  and propose a new method to analyze TDI-CCD imaging noise with statistical probability distribution. In order to estimate the distribution of gray values affect by noise we introduced the concept of skewness and kurtosis. We design an experiment using constant illumination light source  take image with TDI-CCD working at different stage such as stage 16  stage 32  stage 48  stage 64 and stage 96  analyse the characteristics of image noise with the method we proposed  experimental results show that the gray values approximately meet normal distribution in large sample cases. 2011 SPIE.  
Study on spectrograph for ionosphere: A broadband imaging instrument prototype for far-ultraviolet (EI CONFERENCE) 会议论文  OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
作者:  Wang S.-R.;  Lin G.-Y.;  Yu L.
收藏  |  浏览/下载：35/0  |  提交时间：2013/03/25
Current research on space-based exploration for the ionosphere needs more advanced technologies. Because the spectral signals in the ionosphere distributing basically in the far-ultraviolet waveband are very weak. Usual spectrometer structures and detectors such as CCD can't receive enough information. Based on this principle of atmospheric sounding  the imaging spectrometer prototype for ionosphere detection application was designed to solve the problem. This prototype consists of the telescope and the imaging spectrometer. The simple structure and small number of mirrors can help higher transmission efficiency be achieved and weak signals detection be implemented. The telescope is an off-axis parabolic mirror and the spectrometer is a modified Czerny-Turner spectral imaging system. Modified Czerny-Turner spectrometer contains a spherical mirror  a fixed plane grating and a toroidal mirror. By adjusting the incident angle to the collimating mirror and using toroidal mirror  coma and astigmatism were corrected well. We also optimize distances between the grating to the focusing mirror and the focusing mirror to the image plane to improve disadvantages of traditional Czerny-Turner structure. Designed results demonstrate that aberrations are substantially corrected  and high image quality can be obtained in broad waveband. The photon counting Wedge-Strip-Anode detector with micro-channel planes as the receiving plane is accepted for the instrument prototype. The other photon counting 2-D detector responding well for weak light such as Cross-Delay line detector and MAMA detector can also be used for detection. The calibration and performances testing system is made of a vacuum system  a deuterium lamp  a monochrometer and the instrument prototype. Results obtained from the experiment show that the spectral resolution is 2.4 nm and the spatial resolution is 80 m. The other calibration experiments are running. The technology of the spectrometer prototype is important for the research and applications of ionosphere remote sensing. 2011 SPIE.  
Design of motion compensation mechanism of satellite remote sensing camera (EI CONFERENCE) 会议论文  OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
Gu S.; Yan Y.; Xu K.; Jin G.
收藏  |  浏览/下载：47/0  |  提交时间：2013/03/25
With the development of aerospace remote sensing technology  the ground resolution of remote sensing camera enhances continuously. Since there is relative motion between camera and ground target when taking pictures  the target image recorded in recording media is moved and blurred. In order to enhance the imaging quality and resolution of the camera  the image motion had to be compensated. In order to abate the effect of image motion to image quality of space camera and improve the resolution of the camera  the compensation method of image motion to space camera is researched. First  the reason of producing drift angle and adjustment principle are analyzed in this paper. This paper introduce the composition and transmission principle of image motion compensation mechanism. Second  the system adopts 80C31 as controller of drift angle  and adopts stepping motor for actuators  and adopts absolute photoelectric encoder as the drift Angle measuring element. Then the control mathematical model of the image motion compensation mechanism are deduced  and it achieve the closed-loop control of the drift angle position. At the last  this paper analyses the transmission precision of the mechanism. Through the experiment  we measured the actual precision of the image motion compensation mechanism  and compared with the theoretical analysis. There are two major contributions in this paper. First  the traditional image motion compensation mechanism is big volume and quality heavy. This has not fit for the development trend of space camera miniaturization and lightweight. But if reduce the volume and quality of mechanism  it will bring adverse effects for the precision and stiffness of mechanism. For this problem  This paper designed a image motion compensation that have some advantages such as small size  light weight at the same time  high precision  stiffness and so on. This image motion compensation can be applicable to the small optics cameras with high resolution. Second  the traditional mechanism control need to corrected  fitting and iterative for the control formula of mechanism. Only in this way  we can get the optimal control mathematical model. This paper has high precision of the control formula derived. It can achieve the high precision control without fitting  It also simplify the difficulty of control mathematical model establishment. This paper designed the range of adjusting of image motion compensation mechanism between -5 +5. Based on choosing-5  -4  -3  -2  -1  0  +1  +2  +3  +4  +4 as the expectation value of the imaginary drift angle  we get ten groups of the fact data in adjusting drift angle measured. The test results show that the precision of the drift angle control system can be achieved in 1. It can meet the system requirements that the precision of the control system is less than 3'  and it can achieve the high-precision image motion compensation. 2011 SPIE.  
Research on lightweight outer baffle for coaxial space camera (EI CONFERENCE) 会议论文  OAI收割
2011 International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2011, August 12, 2011 - August 14, 2011, Harbin, China
作者:  Zhang L.;  Zhang L.
收藏  |  浏览/下载：17/0  |  提交时间：2013/03/25
Stray light is non-imaging light that reach the optical system imaging plane. The non-imaging light can be received by detector if it is not effectively controlled  and stray light which directly irradiates on the detector has great influence on the imaging quality. Stray light can be effectively inhibited  if the outer baffle of space camera is designed optimally. Carbon fiber composite material is chosen as main material to meet requirements of a coaxial space optical system. The outer baffle should have advantages  such as lightweight  high stiffness and dimensional stability  etc. Using optimization design tools  the lightweight outer baffle is designed. And finite element method is used to check the structure. Development and test results show that the outer baffle with a diameter of 620mm and a total length of 1200mm only weighs 7.3kg. And the baffle's natural frequency reaches 88Hz  and it can satisfy the requirements of the space camera. 2011 IEEE.  
The development and design of the chemiluminescence detection system based on DSP (EI CONFERENCE) 会议论文  OAI收割
2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China
Zhu J.-W.
收藏  |  浏览/下载：20/0  |  提交时间：2013/03/25
Scene matching based on directional keylines and polar transform (EI CONFERENCE) 会议论文  OAI收割
2010 IEEE 10th International Conference on Signal Processing, ICSP2010, October 24, 2010 - October 28, 2010, Beijing, China
作者:  Wang Y.;  Wang Y.;  Wang Y.;  Wang Y.;  Wang Y.
收藏  |  浏览/下载：24/0  |  提交时间：2013/03/25
Scene matching under complex background is a priority and difficulty in the field of computer vision  it has the characteristics of rotation and scaling invariance  commonly used in matching real-time collected images and photos for navigation. Scene matching techniques are faced with complex natural scenes  anti-light and anti-slight-distortion  the image distortion exist  applicable for complex scene matching. The project has a new idea: combining the keylines with the vectors description based on polar image translation  such as light  and utilize the rotation-scale-invariance vectors to describe the extracted keylines  change of gray levels  this method includes three steps: keylines extraction  perspective  description and matching. Preliminary experiments show that this keylines-based scene matching algorithm is applicable for image matching under complex background. 2010 IEEE.  scaling and other differences  which cause matching difficult. This paper aims to find a scene matching algorithm  
High accuracy star image locating and imaging calibration for star sensor technology (EI CONFERENCE) 会议论文  OAI收割
6th International Symposium on Precision Engineering Measurements and Instrumentation, August 8, 2010 - August 11, 2010, Hangzhou, China
作者:  Wang Y.;  Wang Y.;  Wang Y.;  Wang Y.;  Wang Y.
收藏  |  浏览/下载：21/0  |  提交时间：2013/03/25
Today aircraft attitude measurement technology plays an important role in an aircraft system because it can provide orientation for aircraft in action. Lately star sensor technology used in aircraft attitude measurement has become more and more popular because of its high accuracy  light weight  without attitude accumulation errors and other advantages. There are three main steps for star sensor to measure aircraft attitude  star image locating  star identification and attitude tracking. The latter two steps are based on the accuracy of star image locating. So it's critical to make efforts to advance the accuracy of star image locating. Some imaging errors  such as spherical aberration or coma aberration  also have negative effect on the accuracy of star image locating  of which the effect is necessarily reduced as well. At the beginning of this article  the structure of star sensor hardware is introduced. Secondly three methods for star image locating are described specifically  which are traditional centroid method  Gauss quadric fitting method and improved Gauss quadric fitting method. Subsequently an imaging calibration method is described for the purpose of reducing the effect of imaging errors. Finally the experiment shows that the accuracy of the star sensor is 2-arc-second. 2010 SPIE.  
New LED illumination optical engine for micro-projection display (EI CONFERENCE) 会议论文  OAI收割
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology, April 26, 2010 - April 29, 2010, Dalian, China
作者:  Meng Z.;  Meng Z.
收藏  |  浏览/下载：18/0  |  提交时间：2013/03/25
A new optical engine consisting of LEDs  rectangular CPC  rectangular lens array and micro display chip DMD is designed by using of KOLA illumination algorithm for micro-projection display. Detail description and analysis of the rectangular CPC and rectangular lens array are provided. The influence due to the size of rectangular CPC and rectangular lens array is analysed for illuminance uniformity on the DMD chip and light energy efficiency of the optical engine system by software ZEMAX. Based on the analysis of parameter of rectangular lens array  the size of rectangular lens array more decrease the illumination uniformity. Experimental results show that the proposed illumination light optical engine can obtain perfect rectangular focula with higher light uniformity more than 90 % and higher energy efficiency of 40 % to meet the needs of micro-projection display  at the same time the designed illumination optical engine compared with other uniformizing light algorithm have advantages such as: lesser capacity  high illumination uniformity. 2010 Copyright SPIE - The International Society for Optical Engineering.