TMT三镜Whiffletree底支撑系统设计与测试方法研究

发布时间：2018-03-09 01:20

本文选题：whiffletree　切入点：底支撑　出处：《中国科学院长春光学精密机械与物理研究所》2017年硕士论文　论文类型：学位论文

【摘要】：随着现代天文学和军事技术的不断发展,我们希望看得越来越远,看清越来越暗弱的目标。由于口径越大的望远镜分辨力和集光能力越强,所以人们不断地建造越来越大的望远镜。三十米望远镜(TMT)代表了当今天文望远镜研制的最高技术水平。TMT三镜作为直接参与光学系统成像的主要元件,其面形精度是影响望远镜成像质量的关键因素之一。针对TMT三镜,为了保证其在工作时保持良好的面形精度,本文设计了其Whiffletree形式的底支撑系统,并对支撑结构的参数敏感性和平衡性调节测试方法进行了分析研究。具体研究内容如下:首先分析总结大口径反射镜底支撑系统的结构形式和基本原理,重点对Whiffletree结构的工作原理进行分析研究。综合考虑各方面因素,最终选择了18点两级Whiffletree结构的底支撑方案。以镜面面形的RMS值为目标函数,优化计算底支撑点的位置,根据最优解的有限元分析结果,镜面面形的RMS值达到105.6nm。接着使用APDL建立TMT三镜底支撑系统的参数化有限元模型,针对Whiffletree结构直接应用在椭圆形反射镜支撑中支撑效果很差的问题,分析提出采用校正力矩法对支撑力进行校正,并对校正力矩进行优化计算,校正后的镜面面形RMS值为107.6nm,基本达到支撑点位置优化时的面形精度。然后考虑到实际加工装配过程中引入的误差会对支撑效果带来未知程度的影响,针对支撑结构主要参数进行了局部敏感性分析和全局敏感性分析,对结构位置误差和平衡性误差的敏感性进行了评估。最后针对Whiffletree结构的平衡性要求,设计了一种Whiffletree结构平衡性调节测试方法,并运用此方法对一套Whiffletree结构进行了调节测试,取得了良好的效果。
[Abstract]:With the development of modern astronomy and military technology, we want to see farther and further, to see the darker and weaker targets, because the larger the aperture of telescopes, the stronger the resolution and the ability to collect light. So people continue to build larger and larger telescopes. The 30 meter telescope represents the highest level of technology developed by today's astronomical telescopes. TMT3 mirrors are the main components directly involved in the imaging of optical systems. The plane shape accuracy is one of the key factors affecting the imaging quality of the telescope. In order to ensure the good surface shape accuracy of the TMT three-mirror, the bottom support system in the form of Whiffletree is designed in this paper. And the parameter sensitivity and balance adjustment test methods of braced structure are analyzed and studied. The specific research contents are as follows: firstly, the structure form and basic principle of large aperture mirror bottom bracing system are analyzed and summarized. The working principle of Whiffletree structure is analyzed and studied emphatically. Considering various factors, the bottom support scheme of 18:00 two-stage Whiffletree structure is selected. The RMS value of mirror surface is taken as the objective function to optimize the position of bottom support point. According to the results of the finite element analysis of the optimal solution, the RMS value of the mirror shape reaches 105.6 nm. Then, the parametric finite element model of the TMT three-mirror bottom support system is established by using APDL. Aiming at the problem that the Whiffletree structure is directly used in the elliptical mirror support, the correction torque method is proposed to correct the supporting force, and the correction moment is optimized. The corrected RMS value of mirror shape is 107.6 nm, which basically reaches the precision of support point position optimization. Then, considering the effect of the error introduced in the actual machining and assembly process, the support effect is unknown. The local sensitivity analysis and the global sensitivity analysis for the main parameters of the braced structure are carried out, and the sensitivity of the structural position error and the equilibrium error are evaluated. Finally, the equilibrium requirements of the Whiffletree structure are discussed. In this paper, a method of adjusting and testing the balance of Whiffletree structure is designed, and a set of Whiffletree structure is tested by this method, and good results are obtained.
【学位授予单位】：中国科学院长春光学精密机械与物理研究所
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH751

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