基于拓扑优化软件Optistruct对500 mm口径后背钻孔式碳化硅主镜进行了结构优化设计。对比了优化设计主镜结构与传统三角形轻量孔主镜在重力场,温度梯度场下其镜面变形情况。校核结果表明基于拓扑优化设计的主镜结构相比于传统的三角形轻量化孔均布式结构具有更好的光学性能以及更轻的质量。最后对比不同的温度梯度场下的镜面变形情况,结合技术要求提出了主镜的温控目标。 Based on the topology optimization software Optistruct, the structural optimization design of the 500 mm back-drilled silicon carbide primary mirror was carried out. The mirror deformation of the optimized primary mirror structure and the traditional triangular primary lens with a small aperture were compared under the gravitational field and the temperature gradient field. The results of the verification show that the primary mirror structure based on topological optimization has better optical performance and lighter weight than the traditional triangular lightweight hole uniform structure. Finally, the contrast of the mirror deformation under different temperature gradient fields is compared with the technical requirements of the main mirror temperature control target.