主镜是空间相机的主要成像部件, 其面形误差和位置误差将会决定成像质量。 设计了一种孔径为Φ660 mm的圆形主镜组件。通过对比6点定位原理实现反射镜体的全约束, 并经三点在背 部支撑主镜, 其中每点均为多层柔性结构。合理分配每点支撑的自由度及刚度, 同时卸载温度变化时 由于材料的线胀系数不同而传递到反射镜上的应力, 使反射镜变形均匀。有限元分析结果表 明, 本文设计的主镜组件的面形误差RMS值达到1/50λ (λ=632.8 nm), 一阶模态达到249 Hz, 并具有良 好的动态刚度。

A primary mirror is a main imaging part of a space camera. Both its surface figure error and position error will decide the quality of imaging. A circular mirror assembly with an aperture of Φ660 mm is designed. It is restricted completely according to the six-point orientation principle. Its backside is supported by three fixers which are flexible multilayer frameworks. By reasonably distributing the freedom and rigidity of each supporting fixer and unloading the stress due to different expansion coefficients of different materials when temperature is changing, the distortion of the primary mirror assembly is symmetrical. The Finite Element Method (FEM) analysis result shows that the primary mirror assembly has a surface figure error (root-mean-square (RMS) value) up to 1/50λ (λ=632.8 nm), a first mode of 249 Hz and good dynamic rigidity.