深低温SiC空间反射镜背部与侧面支撑结构对比

在深低温下的反射镜及其支撑结构设计中,温度变化作用下的面形精度是空间反射镜性能的重要影响因素。以温度变化作用下的面形RMS为性能指标,基于碳化硅反射镜不同支撑结构和不同材料搭配形式下对空间反射镜的面形变化进行对比研究。首先,在深低温下对背部支撑和侧面支撑的以下两种情况进行仿真分析:(a)反射镜和支撑结构都用碳化硅制造;(b)反射镜用碳化硅制造,支撑结构用其他材料制造。仿真分析得到在(a)条件下背部支撑结构能获得更好的面形,在(b)条件下,侧面支撑结构能获得更好的面形;然后对侧面支撑结构中不同材料搭配情况下对面形精度的影响进行研究,对面形RMS与反射镜材料的线膨胀系数,支撑结构材料的线膨胀系数和反射镜材料与支撑结构材料的线膨胀系数之差的绝对值之间的关系用多元线性回归方法进行统计分析,研究其影响程度,分析得到线膨胀系数之差的绝对值对面形精度RMS的影响更大。研究取得的成果和研究思路对今后的深低温光学反射镜及其支撑结构设计提供参考。

Comparison of back supporting structure and side supporting structure of space mirror manufactured by silicon carbide in cryogenic environment

In the design of mirror and its supporting structure in cryogenic environment, the surface accuracy under the temperature variation is an important factor affecting the performance of the space mirror. The surface shape RMS under the temperature change was taken as the performance index, and the surface shape variation of the space mirror was compared and studied based on the different supporting structures of the mirror manufactured by silicon carbide and the collocation forms of different materials. Firstly, the following two conditions of back support and lateral support were simulated and analyzed in cryogenic environment:(a) the mirror and the supporting structure was made of silicon carbide; (b) the mirror was made of silicon carbide and the supporting structure was made of other materials. Simulation analysis shows that the back support structure can obtain a better surface shape under condition (a), and the lateral support structure can obtain a better surface shape under condition (b). Then, the influence of the side supporting structure on the surface accuracy under different material matching conditions was studied. The relationship among the RMS and the CTE(coefficient of linear thermal expansion) of mirror material, the CTE of supporting structure materials, the absolute value of the difference between the CTE of mirror material land the CTE of supporting structure materials was analyzed using multivariate linear regression method. The analysis result shows that the absolute value of the difference between the CTE of mirror material and the CTE of supporting structure materials has greater influence on the RMS. The research results and ideas provide reference for the design of cryogenic optical mirror and its supporting structure in the future.