为解决传统柔性支撑中小口径空间反射镜组件热稳定性与结构刚度间的矛盾，提出了一种新型刚性支撑结构，并为某高分辨率空间相机研制了通光口径?214 mm的高精度次镜组件。采用“镜体-锥套-支撑筒-刚性基板”组合，通过延长、优化热应力在组件内部的传递路径实现了消热目的。刚性支撑次镜组件重2.6 kg、4 ℃均匀温升工况下面形变化均方根（RMS）仿真值为2.573 nm，装调重力工况下镜体倾角和位移分别为2.028″、0.566 μm，与传统柔性支撑方案相比具有突出的优势。实测次镜的面形精度RMS为0.0181λ（λ=632.8 nm），在16 ℃及24 ℃时次镜面形变化量不超过0.0025λ；组件基频达到502.1 Hz，在快速高低温循环及大量级振动后次镜面形基本维持不变；装配容差测试中，次镜在0.02 mm不平度的作用下仅发生微弱变形。刚性支撑结构可以显著提升中小口径反射镜工作性能，在遥感器光机结构研制领域内具有广阔的应用前景。

A novel rigid support structure is proposed in this paper to solve the contradiction between thermal stability and structural stiffness in small- and medium-aperture space mirrors assembled using traditional flexible supports. Additionally, a high-precision secondary mirror assembly with a clear aperture of ?214 mm is developed for a high-resolution space camera. The combination of a mirror body, cone, support cylinder, and rigid base plate is adopted to realize heat dissipation by extending and optimizing the transmission path of the thermal stress within the assembly. The secondary mirror assembly with a rigid support structure weighs 2.6 kg, and the surface accuracy change has a root-mean-square (RMS) value of 2.573 nm in the simulation under the condition of a 4 °C uniform temperature rise. The inclination and displacement of the mirror body subjected to the gravity test are 2.028" and 0.566 μm, respectively, revealing the outstanding advantages of the proposed scheme over traditional flexible support systems. The measured surface accuracy RMS value of the secondary mirror is 0.0181λ (λ=632.8 nm), and the changes in the surface accuracy at 16 and 24 °C do not exceed 0.0025λ. The fundamental frequency of the assembly reaches 502.1 Hz, and the surface accuracy of the secondary mirror remains relatively unchanged after rapid heat cycles and large-scale vibrations. In the assembling tolerance test, the secondary mirror is only slightly deformed under 0.02 mm unevenness. The proposed rigid support structure can significantly improve the working performance of small- and medium-aperture mirrors and has broad application prospects in the optomechanical structural design of remote sensors.