空间相机消杂光设计及仿真

Stray light removing design and simulation of spaceborne camera

针对空间相机中的杂光会引起像质模糊和对比度下降问题,设计了空间相机消杂光机构。研究的空间相机基于同轴三反系统,消杂光机构主要由内外镜筒、视场光阑、里奥光阑和挡光板组成。在内外镜筒的设计中参考了卡塞格林系统的设计方法并利用CAD建模进行辅助设计。为了对消杂光效果进行评价,采用了基于计算机随机光线Monte-Carlo仿真方法。介绍了对表面的散射特性进行描述的双向散射模型、关键面的选取和模型的建立。利用计算机分析得到了空间相机的杂光系数和点源透射比的曲线,子午方向+10°入射的杂光在像面造成的杂光系数在0.35%以下,0～20°的非成像视场点源透射比为10-6量级,该结果可作为进一步优化设计消杂光系统的参考依据。

A stray light removing mechanism is designed for improving image contrast and image deblurring in a spaceborne camera. The spaceborne camera researched in this paper is based on on-axis Three Mirror Anastigmatics（TMA）, and the stray light removing mechanism consists of inner and outer baffles, field stop, Lyot stop and blocking board. Cassegrain system is taken as a reference in the CAD modeling for design of inner and outer baffles and the random light Moente-Carlo simulation method is adopted to evaluate the effect of stray light removing. Moreover, the Bidirectional Scattering Distribution Function（BSDF） for describing the scatter character of surfaces, choice of key surfaces and the establishment of model are introduced and the stray light ratio and Point Source Transmittance （PST） curves are acquired by computer analysis. Results show that the stay light ratio is below 0.35% when stay light incidents at ＋10° meridional direction and the PST is at the level of 10^-6 in 0-20°. These results can offer a good reference for the further optimization design.