中国科学院机构知识库网格系统: 检索

Effect of adhesive on surface accuracy and adaptability analysis of large aperture rectangular mirror 会议论文 OAI收割
Hybrid, Xi�an, China, 2023-10-20
作者: Feng, Jun; Wang, Feicheng; Chen, Wencong; Li, Siyuan; Tian, Feifei

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收藏 | 浏览/下载：10/0 | 提交时间：2024/08/16

adhesive curing shrinkage surface shape accuracy topology optimization environmental adaptability analysis

Accuracy Assessment of the Planar Morphology of Valley Bank Gullies Extracted with High Resolution Remote Sensing Imagery on the Loess Plateau, China 期刊论文 OAI收割
INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH, 2019, 卷号: 16, 期号: 3, 页码: 19
作者: Chen, Yixian; Jiao, Juying; Wei, Yanhong; Zhao, Hengkang; Yu, Weijie

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收藏 | 浏览/下载：69/0 | 提交时间：2019/05/22

valley bank gully Pleiades imagery visual interpretation accuracy assessing standard gully detection limit gully dimensions vegetation cover gully shape complexity broken topography

Design of Spatial Oval Plane Mirror and Its Support Structure 会议论文 OAI收割
Nanjing, PEOPLES R CHINA, 2017-10-24
作者: Chai Wenyi; Hu Yongming; Wang Chenjie; Chen Su; Feng Song

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收藏 | 浏览/下载：39/0 | 提交时间：2018/07/05

Spatial Oval Mirror Lightweight Shape Accuracy Flexible Support Environmental Experiment

The effect of temperature distribution on reflectors in satellite optical terminals 会议论文 OAI收割
Nanjing, PEOPLES R CHINA, 2017-10-24
作者: Wang Chenjie; Shangguan Aihong; Chai Wenyi; Hu Yongming; Tao, Wenquan

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收藏 | 浏览/下载：38/0 | 提交时间：2018/07/05

Reflectors Temperature Distribution Shape Accuracy Thermal-optical Vacuum Experiment Active Thermal Control

Corner detection using Gabor filters 期刊论文 OAI收割
iet image processing, 2014, 卷号: 8, 期号: 11, 页码: 639-646
作者: Zhang, Wei-Chuan; Wang, Fu-Ping; Zhu, Lei; Zhou, Zuo-Feng

收藏 | 浏览/下载：51/0 | 提交时间：2015/03/19

edge detection Gabor filters grey systems affine transforms Gabor filter contour-based corner detection magnitude response edge contour shape analysis local curvature maxima points planar curve corresponding grey-variation information Canny edge detector normalised magnitude response magnitude response threshold angle threshold detection accuracy localisation accuracy afflne transform noise-robustness

A shape context based Hausdorff similarity measure in image matching 会议论文 OAI收割
5th International Symposium on Photoelectronic Detection and Imaging (ISPDI) - Infrared Imaging and Applications, Beijing, June 25-27, 2013
作者: Ma TL(马天磊); Liu YP(刘云鹏); Shi ZL(史泽林); Yin J(尹健)

收藏 | 浏览/下载：36/0 | 提交时间：2013/12/26

The traditional Hausdorff measure, which uses Euclidean distance metric (L2 norm) to define the distance between coordinates of any two points, has poor performance in the presence of the rotation and scale change although it is robust to the noise and occlusion. To address the problem, we define a novel similarity function including two parts in this paper. The first part is Hausdorff distance between shapes which is calculated by exploiting shape context that is rotation and scale invariant as the distance metric. The second part is the cost of matching between centroids. Unlike the traditional method, we use the centroid as reference point to obtain its shape context that embodies global information of the shape. Experiment results demonstrate that the function value between shapes is rotation and scale invariant and the matching accuracy of our algorithm is higher than that of previously proposed algorithm on the MEPG-7 database.

Technology on fabrication of precise SiC aspherical mirror (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Materials and Products Manufacturing Technology, ICMPMT 2011, October 28, 2011 - October 30, 2011, Chengdu, China
Zhang Z.

收藏 | 浏览/下载：26/0 | 提交时间：2013/03/25

This paper represents a technique to produce the large size optical aspherical mirror by using reaction-bonded silicon carbide to meet the material requirements of the space used mirrors based on the characters comparison of all types mirror material. Techniques are described in this paper including the bonding procedure of silicon carbide to form a mirror shape the CCOM technology for aspheric grinding polishing on a home-developed tool -FSGJ-2 and the aspheric profilometry. A specialized Offner Null lens is also developed to measure the aspherical mirror with laser interferometer. With the technology depicted in the paper a 502mm 298 mm off-axis SiC aspherical mirror is successfully made with a surface accuracy better than 1/50rms the final result meets the design requirement. (2011) Trans Tech Publications.

The optical design of cubic phase plate testing system (EI CONFERENCE) 会议论文 OAI收割
2011 Symposium on Photonics and Optoelectronics, SOPO 2011, May 16, 2011 - May 18, 2011, Wuhan, China
作者: Zhang X.; Zhang X.; Zhang X.; Zhang Y.

收藏 | 浏览/下载：19/0 | 提交时间：2013/03/25

Computer-generated holograms (CGH) have been widely used for years in optical testing of aspheric surfaces in combination with Fizeau interferometers. With the development of diffraction optics computer technology and micro-processing technology the accuracy of the CGH testing can achieve a hundredth of a wave and the cost is reduced greatly. CGH is capable of producing an optical wavefront with any desired shape. So it is fascinating and will have good prospects to test free-form surfaces using CGH. As the CGH can create any wavefront shape it can also be used in unsymmetrical aspherical surfaces testing. Taking the cubic surface as an example this paper gives a method to test unsymmetrical surfaces. This paper gives the design to test a cubic surface. And the separation of the diffraction orders and the binary process of the continuous CGH phase function are discussed in detail. The alignment tolerance of the test system and the CGH fabrication tolerance are analyzed. We also present an idea using a CGH and two spherical lenses as null lens to test the cubic surface when the surface deviation is great. 2011 IEEE.

Adaptive Wiener filtering with Gaussian fitted point spread function in image restoration (EI CONFERENCE) 会议论文 OAI收割
2011 IEEE 2nd International Conference on Software Engineering and Service Science, ICSESS 2011, July 15, 2011 - July 17, 2011, Beijing, China
作者: Yang L.; Zhang X.; Zhang X.; Zhang X.; Yang L.

收藏 | 浏览/下载：41/0 | 提交时间：2013/03/25

In the imaging process of the space remote sensing camera there was degradation phenomenon in the acquired images. In order to reduce the image blur caused by the degradation the remote sensing images were restored to give prominence to the characteristic objects in the images. First the frequency-domain notch filter was adopted to remove strip noises in the images. Then using the ground characters with the knife-edge shape in the images the point spread function of the imaging system was estimated. In order to improve the accuracy the estimated point spread function was corrected with Gaussian fitting method. Finally the images were restored using the adaptive Wiener filtering with the fitted point spread function. Experimental results of the real remote sensing images showed that almost all strip noises in the images were eliminated. After the denoised images were restored its variance and its gray mean gradient increased also its laplacian gradient increased. Restoration with Gaussian fitted point spread function is beneficial to interpreting and analyzing the remote sensing images. After restoration the blur phenomenon of the images is reduced. The characters are highlighted and the visual effect of the images is clearer. 2011 IEEE.

Research on automatic Hartmann test of membrane mirror (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: Zhang P.

收藏 | 浏览/下载：29/0 | 提交时间：2013/03/25

Electrostatic membrane mirror is ultra-lightweight and easy to acquire a large diameter comparing with traditional optical elements so its development and usage is the trend of future large mirrors. In order to research the control method of the static stretching membrane mirror the surface configuration must be tested. However membrane mirror's shape is always changed by variable voltages on the electrodes and the optical properties of membrane materials using in our experiment are poor so it is difficult to test membrane mirror by interferometer and null compensator method. To solve this problem an automatic optical test procedure for membrane mirror is designed based on Hartmann screen method. The optical path includes point light source CCD camera splitter and diffuse transmittance screen. The spots' positions on the diffuse transmittance screen are pictured by CCD camera connected with computer and image segmentation and centroid solving is auto processed. The CCD camera's lens distortion is measured and fixing coefficients are given to eliminate the spots' positions recording error caused by lens distortion. To process the low sampling Hartmann test results Zernike polynomial fitting method is applied to smooth the wave front. So low frequency error of the membrane mirror can be measured then. Errors affecting the test accuracy are also analyzed in this paper. The method proposed in this paper provides a reference for surface shape detection in membrane mirror research. 2010 Copyright SPIE - The International Society for Optical Engineering.