大型光学望远镜扇形子镜拼接设计及仿真分析

Design and Simulation of Splicing of Sector-Shaped Segments of a Large Optical Telescope

目前,国际上大型望远镜拼接镜面采用的拼接子镜几乎都是六边形而没有采用扇形。比较六边形子镜和扇形子镜各方面的优缺点,建立六边形和扇形子镜的有限元模型,均采用18点轴向支撑,优化支撑方式,计算各子镜在自重作用下,镜面在水平位置,倾斜45°和垂直位置时的变形参数RMS值。结果表明在面积和支撑点数目均相同的条件下,扇形子镜在理论上可以获得与六边形子镜近似的镜面RMS值,但是在实际应用中扇形子镜的支撑,镜面调控与六边形子镜相比将更加复杂困难。

In instead of seetor-s almost all large telescopes of segmented primary mirrors in the world hexagonal segments haped segments are adopted. We compare the advantages and disadvantages of hexagonal segments and sector-shaped segments, and establish finite-element model of both types of segments with optimized 18 axial-support points. We further calculate the surface-deformation patterns of segments due to gravity when these segments are in three different directions, being laid horizontally, put vertically, and 45° from vertical. Our results show that sector-shaped segments can in principle have almost the same surface RMS as hexagonal segments if these two types of segments have the same area and number of axial-support points. However, sector-shaped segmented mirrors practically require much more complicated support and control systems.