大型离轴三反相机主镜组件结构设计与验证

大口径长条形反射镜是大型离轴三反相机的核心部件之一，针对“吉林一号”宽幅01C星中通光口径为1 250 mm×460 mm的主反射镜，系统论述了1.2 m量级大长宽比反射镜组件的结构设计方法，并对所研制的主镜开展了详细的验证。从材料属性和现有工艺出发，镜体材料选择反应烧结碳化硅，采用半封闭式轻量化形式，通过二目标全局优化确定了镜体结构参数的最佳组合，最终镜体设计质量为41.8 kg，面板厚5 mm、最薄加强筋仅厚3 mm。采用经典背部三点支撑方案，优化柔性支撑中的双轴柔性铰链结构参数以兼顾组件基频和热稳定性，并与镜体质心位置进行匹配。提出了主镜组件的装配流程和相应的消应力措施。测试结果表明：主镜在装调重力工况下全口径面形精度均方根值为0.016λ(λ=632.8 nm)，翻转180°后主镜全口径面形精度均方根值为0.019λ；实测主镜组件一阶基频为127.8 Hz，经大量级随机振动和高低温循环后，主镜面形精度均方根值基本不变。主镜组件具有良好的动、静力学特性，且面形精度高、稳定性良好，能够满足高性能空间光学系统的使用要求。

Structure design and verification of primary mirror assembly for large off-axis TMA camera

Large aperture rectangular mirror is one of the core components in large off-axis TMA camera, focusing on the primary mirror with clear aperture of 1250 mm×460 mm in Jilin-1KF01C satellite, the structural design method for 1.2 m scale mirror assembly with large aspect ratio was systematically discussed, and the developed mirror was verified in detail. Based on material properties and existing processes, the mirror body was made of reaction bonded silicon carbide, semi-closed lightweight form was adopted, the optimal combination of structural parameters was determined through two-objective global optimization. The final design weight of mirror body was 41.8 kg, with the facepanel 5 mm thick and the thinnest stiffener 3 mm thick. The classical back three-point support scheme was adopted, the structural parameters of the biaxial flexure hinge in the flexible support were optimized, so as to take into account fundamental frequency and thermal stability of the component, and match the centroid position of the mirror body. The assembling process for the primary mirror assembly and the corresponding stress relief measures were put forward. Test results showed that the full aperture surface accuracy of primary mirror under testing gravitational condition was 0.016λ (λ=632.8 nm) in root mean square value, and the full aperture was 0.019λ after turning 180°. The tested 1st fundamental frequency of the assembly was 128.5 Hz, and the root mean square value of primary mirror basically remained stable after large scale random vibrations and wide range temperature cycles. The primary mirror assembly not only has good dynamic and static characteristics, but also has the features of high surface accuracy and good stability, which can meet the application requirements of high-performance space optical system.