反射镜轻量化设计一直是光机结构设计领域的一项挑战性课题。针对某机载红外光学系统的主反射镜，提出了一种基于SIMP 拓扑优化方法的反射镜轻量化设计流程，建立了反射镜拓扑优化的数学模型，以最小化镜体自重和抛光载荷作用下的镜面矢高位移RMS 值为优化目标，同时考虑对称约束和拔模约束，对反射镜进行了拓扑优化设计。根据拓扑优化结果设计了新的反射镜轻量化结构，并将其与传统结构进行了对比。采用拓扑优化方法设计的反射镜具有更高的轻量化率，同时能够获得较高的面形精度。

The lightweight design of mirror has always been a challenging task in the field of opto-mechanical structure design. For the lightweight design of the primary mirror in an airborne infrared optical system, a lightweight mirror design procedure is proposed based on the SIMP topology optimization method. The mathematical model of topology optimization is established. With the objective of minimizing the RMS value of surface sag displacements under the load of gravity parallel to the optical axis and polishing pressure, the mirror is optimized by using topology optimization method while symmetry and casting constraint considered. According to the topology optimization result, a new lightweight mirror configuration is designed. The proposed mirror is compared with a traditional lightweight structure. The comparison results show that the lightweight ratio of the mirror obtained by using topology optimization method is higher than the traditional one. And a high optical surface accuracy can be achieved.