长条形反射镜的集成优化设计

摘要

离轴三反系统(TMA)在具有高分辨率、大视场的空间遥感器中被广泛使用，长条形反射镜作为 TMA 系统中的核心元件，其自身的性能直接影响遥感器的成像质量。本文在传统反射镜轻量化结构的基础上，为改善反射面局部面形质量，提出一种变筋厚设计方案；为了确定各结构参数的最佳取值，将反射面的面形精度和镜体质量同时作为目标函数，采用邻域培植多目标遗传算法(Neighborhood Cultivation Genetic Algorithm, NCGA)对其进行集成优化求解；结合制造工艺的约束，调整并确定该反射镜最终的设计方案。在z向1 g工况下，优化后的反射镜RMS值为1.278 nm、PV值为5.642 nm，分别较初始结构(RMS=1.947 nm，PV=8.349 nm)降低了34.4%和32.4%，且质量比初始结构略有减轻，从而兼顾了面形精度和镜体质量。这说明本文所提出的轻量化方案和结构参数确定方法适用于TMA系统中长条形反射镜轻量化结构的设计，对今后相关元件的研制具有一定的参考价值。%Off-axis Three-mirror system (TMA) is widely used in space remote sensors with high resolution and wide field of view, in which rectangular reflective mirror is regarded as the core component, for its performance directly influences imaging quality. Based on traditional light-weighted structure for reflective mirror, bring forward a plan with variable rib thickness design in order to improve local surface quality. Take both the quality of reflective surface and the mass of mirror as objectives, use NCGA algorithm to solve the multi-objective optimization problem and ascertain the best combination of structure parameters. Modify the optimized design according to manufacturing constraints. Under the load condition of gravity in z-direction, the RMS value of final design is 1.278 nm, with the PV value of 5.642 nm, which is respectively 34.4% and 32.4% smaller than the original design ( RMS=1.947 nm, PV=8.349 nm ). Meanwhile, the mirror is lighter, satisfying the demand of high surface quality and light structure. This suggests that the light-weighted plan and the method of determining parameters proposed in this paper are effective for the light-weighted design of rectangular reflective mirror used in TMA system, and have reference value for future development of related elements.