主反射镜的面形精度对空间相机的成像质量至关重要。为保证 空间相机在宽温度范围(20±10℃)内的成像质量，设计了一种柔性支撑结构。首先，选择碳化硅(SiC) 作为反射镜材料，并对主反射镜镜体进行了背部半封闭式轻量化处理。其次，针对这个孔径为550 mm的圆 形主镜组件在20±10℃温度范围内的使用环境，设计了一种柔性铰链结构。利用Matlab软件优化了支撑结构参 数，使得支撑柔性结构在受到温度载荷时沿着径向具有足够的柔性，并可吸收变形和降低反射镜应 力。通过有限元分析可以看出，该支撑结构的一阶频率达到267 Hz，远高于机身组件的固有频率，因此可保 证主镜组件不遭到破坏。而且在重力耦合10℃温度载荷时，反射镜的面形误差(RMS值)也满足光学 系统优于λ/40的要求。

The figure shape precision of primary mirrors are most important for the imaging quality of space cameras. To ensure a space camera to have high imaging quality in a wide temperature range (20±10℃), a flexible support structure is designed. Firstly, the SiC material is selected to make the mirror and semi-enclosed type light-weight processing is carried out for the back of the primary mirror body. Secondly, for the environment in the temperature range of 20±10℃ in which the round primary mirror module with an aperture of 550 mm will be used, a flexible articulated structure is designed. Because the parameters of the supporting structure are optimized by the Matlab software, the flexible supporting structure has enough radial flexibility and can absorb distortion so as to reduce the stress of the mirror. The finite element analysis result shows that the supporting structure has the first-order frequency of 267 Hz which is much higher than the inherent frequency of the mirror body module. So, it can ensure the primary module not to be damaged. Even when the gravitation is coupled with the temp-erature load of 10℃, the mirror can meet the requirement of the figure shape error (RMS) less than λ/40 of the optical system.