变厚变曲率反射镜及其在空间相机中的应用

Variable Curvature Mirror with Variable Thickness and Its Application in Space-Borne Optical Camera

变曲率反射镜是一种主动光学元件,通过改变自身曲率半径实现对波前的动态控制。首先对变曲率反射镜国内外现状及发展趋势进行了综述;其次,建立了变厚变曲率反射镜形变物理模型,对兼顾大中心形变与高面形精度的机理进行了理论分析,并通过形变的面形精度保持实验对其性能进行了验证;最后,从三个方面探索了变厚变曲率反射镜在空间光学相机中的应用:1)针对大变倍比变焦成像对反射镜超大中心形变的要求,设计了基于有限元迭代并叠加高阶球差的反射镜优化流程,实现了近毫米级中心形变反射镜设计;2)针对空间光学相机成像对调焦精度及速度的要求,提出了基于次镜变曲率反射镜的高精度大动态调焦方法;3)提出了积分时间内利用变曲率次镜沿光轴方向快速扫描的编码成像方法。

A variable curvature mirror is a kind of active optical element.By changing its curvature radius,the corresponding wave-front could be dynamically controlled.First of all,the current situation and development trend of variable curvature mirrors are summarized systematically.After that,the physical model of deformation of variable curvature mirrors with variable thickness is established and the capability of this kind of variable curvature mirror in generating large saggitus and maintaining good surface figure accuracy is proven through numerical simulation and experiments.Finally,the application of variable curvature mirrors with variable thickness in space optical cameras is explored from three aspects.In the first place,in order to satisfy the requirement for the super large saggitus variation required by realizing large magnification ratio zoom imaging,a finite element alternating(FEA)based optimization procedure by incorporating high-order spherical deformation is designed,and the mirror with the saggitus variation approaching 1 mm is obtained.In the second place,aiming at the requirements of focusing accuracy and speed in space camera imaging,a high-precision large dynamic focusing method based on sub-mirror variable curvature mirrors is proposed.In the third place,a coding imaging method using a variable curvature secondary mirror to scan quickly along the optical axis during integration time is proposed.