TMT三镜被动支撑技术研究

发布时间：2018-05-23 18:30

本文选题：TMT + 三镜　；参考：《中国科学院研究生院（长春光学精密机械与物理研究所）》2012年硕士论文

【摘要】：随着人类对宇宙进行的探索不断地深入,对天文望远镜的口径的需求也越来越大,三十米望远镜(TMT)代表了当代天文望远镜制造领域的最前沿,而镜子的面形精度是影响望远镜成像质量的关键因素之一,本文正是基于TMT的三镜进行了镜子支撑结构的设计与研究,以达到要求的面形精度。通过查阅文献资料,对国内外大口径地基望远镜的发展和现状进行了调研和总结；研究了镜子支撑的基础理论,对各种底支撑和侧支撑结构形式进行了归纳和总结；阐述了有限元分析的基本原理,主要对有限元静力学分析和有限元模态分析进行了学习和研究。根据TMT三镜的情况,底支撑选用18点两级whiffle tree被动支撑形式,利用有限元软件Ansys优化分析出18个支撑点的最佳支撑位置,初步设计出的底支撑结构,然后利用有限元软件MSC.Patran/Nastran进行有限元建模和分析。根据分析的结果对所设计的支撑结构进行修正,消除了由结构不对称引入的镜面不对称变形的影响,最终镜面的RMS值为99.7nm,符合设计要求；同时还设计了另一种半主动式底支撑结构,同样符合镜面的面形精度要求。通过研究和分析发现,对于TMT这种实心平面镜来说,侧支撑点的位置和数量对其面形的影响不大,只在镜子边缘的支撑点附近有影响。借鉴底支撑的设计经验,侧支撑仍然采用whiffle tree结构,共有12个支撑点,经过有限元分析和改正,最终在侧支撑的作用下镜面的RMS值达到了14.1nm,满足设计要求。最后分析了底支撑和侧支撑综合作用下的面形,满足设计要求。
[Abstract]:As mankind's exploration of the universe continues to deepen, the demand for the caliber of astronomical telescopes is growing, and the 30-meter telescope (TMTT) represents the most advanced field in the manufacture of contemporary astronomical telescopes. The mirror shape accuracy is one of the key factors that affect the imaging quality of the telescope. In this paper, the design and research of the mirror supporting structure based on TMT are carried out in order to achieve the required surface shape accuracy. The development and current situation of large caliber ground-based telescopes at home and abroad are investigated and summarized, the basic theory of mirror bracing is studied, and various forms of bottom and side bracing structures are summarized and summarized. The basic principle of finite element analysis (FEM) is expounded, and the finite element statics analysis and finite element modal analysis are studied. According to the condition of TMT three mirrors, 18 points two-stage whiffle tree passive support is used in the bottom support. The optimal support position of 18 support points is optimized by using the finite element software Ansys, and the primary design of the bottom support structure is obtained. Then the finite element modeling and analysis are carried out by using finite element software MSC.Patran/Nastran. According to the results of the analysis, the designed bracing structure is modified to eliminate the influence of the asymmetric deformation of the mirror surface introduced by the structural asymmetry. The final RMS value of the mirror surface is 99.7 nm, which conforms to the design requirements. At the same time, another semi-active bottom support structure is designed, which also meets the precision requirement of mirror surface. Through research and analysis, it is found that the position and number of side support points have little effect on the surface shape of TMT solid plane mirror, but only near the supporting point of the mirror edge. For reference to the design experience of the bottom bracing, the side bracing still adopts whiffle tree structure, which has 12 supporting points. Through finite element analysis and correction, the RMS value of the mirror surface under the action of the side brace finally reaches 14.1 nm, which meets the design requirements. Finally, the surface shape under the combined action of bottom bracing and side bracing is analyzed to meet the design requirements.
【学位授予单位】：中国科学院研究生院（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】：2012
【分类号】：TH751

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