中国科学院机构知识库网格系统: 检索

中国科学院机构知识库网格

Chinese Academy of Sciences Institutional Repositories Grid

机构

采集方式

内容类型

发表日期

学科主题

筛选

浏览/检索结果: 共2条，第1-2条

帮助

条数/页：排序方式：
	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：69/0 \| 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.
	Gimbal displacement error analysis on an electro-optical seeker (EI CONFERENCE) 会议论文 OAI收割 Optical Design and Testing IV, October 18, 2010 - October 20, 2010, 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 It is essential to analyze the gimbal displacement errors for a seeker due to the importance for cueing of targets and tracking for the final approach. Otherwise for a seeker electro-driven with a concentric glass dome the large errors will decrease the picking pointing and tracking precision rooted from the displacement errors existing between the rotation center of the optical system and the gimbal. And the gimbaled camera system displacement errors are never eliminated but reduced due to the geometric errors consists of geometric tolerances of gimbal structure manufacture installation and vibration coming from working environment. In this paper the gimbal displacement errors in an electro-optically stabilized platform resulting from geometric errors and environment errors were analyzed and shown in detail. The mathematical modal of the gimbal displacement errors created based on multi-body dynamics demonstrated the connection between the gimbal displacement errors and the stabilized platform. Taking a visible light image seeker as a case the diameter is 120mm and the geometric tolerances came from the values of primary design and the vibration data came from the environmental vibration test on the pitch-yaw seeker and at the same time the errors resulting from installation were considered too. Based on calculating the maximum gimbal displacement error will reach to 0.2mm for pitching angle smaller than 40 and yawing angle smaller than 60. However the critical parts have been found out according to the probability theory and the reliability analysis successfully used in the paper and finally the maximum gimbal displacement error reduced to 0.1mm which is acceptable corresponding to the picking pointing and tracking precision for an optical imaging seeker. 2010 Copyright SPIE - The International Society for Optical Engineering.