根据某空间光学系统的SiC 反射镜的设计指标要求,对比分析了各种轻量化结构(包括三角形、正方形、六边形和各种扇形轻量化结构)的力学(自重变形)、热学性能(温度应力变形)。综合比较这些轻量化结构的轻量化率、比刚度和热稳定性能,最终确定采用一种扇形轻量化结构。在轻量化率达到75%的情况下,镜体的自重变形和热变形均满足要求:采用Zernike 多项式拟合去除刚体位移后得出,在周边支撑情况下镜面由于自重引起的表面畸变量的RMS 值为0.010 1 μm,约为λ/60(λ=0.632 8 μm)。

According to the design targets of a mirror which is made with the material SiC in a certain space optical system, analyze and contrast the calorific capability (which is figured by the deformation caused by the different temperature) and the mechanical capability (which is figured by the deformation caused by the gravity) of many different light-weighted structures (such as triangle, square, hexagon and various sectors). Then, decide to use one of the sector light-weighted structures after contrasting and balancing the light-weighted percent, rigidity ratio (which is the ratio of the elastic model-E and the density of the material) and the calorific stability. With the sector light-weighted structure, the light-weighted ratio reaches 75 percent, and the deformation brought by the gravity and the calorific deformation are both enough small for use. The RMS of aberration-deformation of the mirror surface with surrounding support is 0.010 1 μm which is about λ/60 (λ=0.632 8 μm). The aberration-deformation does not contain the rigid displacement of the mirror surface which is removed by using the Zernike polynomial to fit the deformation of the mirror surface calculated by the MSC software.