Φ450mm口径空间天文相机轻量化碳化硅主反射镜组件设计

Design ofΦ450mm light-weighted SiC mirror subsystem in space-based astronomy telescope

针对某空间天文相机对轻量化、光学效率、杂光抑制与探测能力的需求,设计Φ450 mm口径碳化硅主反射镜,镜体轻量化率超过70%;选取线膨胀系数匹配的殷钢材料,设计基于两脚架柔性结构的侧面支撑以消除装配应力和热应力,通过渗硅改性获取高反射率光学镜面。光学加工完成后反射镜质量7 kg,反射率优于98%。在严格的工艺条件控制下,对反射镜组件进行精密装配。光学检测结果表明,反射镜装配完成后面形误差优于0.02λRMS,与分析结果吻合。证明了空间天文相机主反射镜组件结构设计方案与装调工艺的合理性,满足空间天文相机光学设计要求。

AΦ450 mm primary mirror subsystem of a space-based astronomy telescope was designed with mass,optical surface distortion and reflectivity requirement.The open-back primary mirror was made of pressureless sintering silicon carbide,light-weighted at a ratio of approximately 70%.Three side supporting invar flexure bipods were designed to minimize the assembling stress and the thermal stress.The high reflection was obtained from the optical surface cementite.The mirror weighted 7 kg and the reflectivity was 98%after optical polishing.The mirror subsystem was precisely assembled under the strict technical condition.The optical test with interferometer show that the optical surface distortion is less than 0.02λRMS,which meet the critical optical requirements for the primary mirror of the space-based astronomy telescope.