Φ1.05 m轻量化反射镜设计与制造

Design and manufacture ofΦ1.05 m lightweight mirror

针对Ф1.05 m空间光学系统主镜的设计指标要求,提出了轻量化反射镜结构优化设计的新方法,并建立了反射镜结构自动化仿真分析与优化设计平台,基于此平台确定了性能优异的主镜结构设计方案。主镜重量小于50 kg,轻量化率已接近国外先进水平;主镜在三球铰支撑下的第一阶模态频率为361.2 Hz,自由状态下的一阶非零模态频率为501.9 Hz;在1℃均匀温度变化下,不去离焦和去除离焦之后的面形RMS分别为0.55 nm和0.10 nm;主镜在30g过载加速度作用下的最大应力为16.1 MPa,均满足设计要求。采用目前最先进的第三代大口径反射镜加工工艺,路线为超精密铣磨—小磨头数控研抛—离子束精修,实现主镜面形误差的确定性去除。为保证面形检测结果的天地一致性,发展了重力卸载技术和面形误差数据后处理技术,剔除重力和其他系统误差对检测的影响。主镜最终面形精度达到0.011λRMS,获得了高精度的光学面形,也证明了方案的合理性。

In terms of the strict design requirements ofФ1.05 m primary mirrors for space optical systems,a new method of structural optimization design of lightweight mirrors is proposed,and a platform for automatic simulation analysis and optimization design of mirror structures are established.The primary mirror design with excellent performances is determined based on that platform.The primary mirror weighs less than 50 kg,and the lightweight ratio is close to the foreign advanced level.The first mode frequency of the primary mirror under the support of three spherical hinges is 361.2 Hz,and the first-order non-zero free modal frequency is 501.9 Hz.Under the uniform temperature change of 1℃,the surface figures with defocus and without defocus are 0.55 nm RMS and 0.10 nm RMS,respectively.The maximum stress of the primary mirror under 30g overload acceleration is 16.1 MPa.All of these performances meet the design requirements.The most advanced third-generation large-aperture mirror processing technology is adopted,and the route is ultra-precision milling,CNC grinding and polishing of small grinding head,and ion beam finishing.In order to ensure the consistency of surface shape test results no matter in the space or on the ground,the gravity unloading technology,and surface shape error data post-processing technology are developed to eliminate the influence of gravity and other systematic errors.The final surface shape accuracy of the primary mirror reaches 0.011λRMS,which shows a high precision optical surface and demonstrates the rationality of the scheme.