星载大视场多光谱成像光学系统设计

Design of Spaceborne Large Field of View Multispectral Imaging Optical System

大视场、多通道、小型化已成为星载测绘光学系统的迫切需求。根据上述需求,提出了先用视场分光再用窄带分色片分光的设计方案、并构建了自动消遮挡和轻小型化优化函数。设计了一款主、次、三镜均为球面的离轴三反四通道光学系统,其焦距360mm、相对孔径为1/6、视场角13°×5°、工作波段0.4~1.1mm、地面像元分辨率5 m、全视场畸变小于5%。加工、装调后的整机系统实测MTF(Modulation Transfer Function)曲线在奈奎斯特频率100 lp/mm处均大于0.25,同时系统所占空间面积仅为245 mm×423 mm、整机重量仅13.82 kg,从而实现了系统大视场、无遮挡、多通道、体积包络的小型化。

A large field of view,multi-channel,lightness,and miniaturization have all become critical requirements for satellite-borne surveying and mapping optical systems.According to the above-mentioned requirements,a design method that uses the field of view to split light and then uses a narrowband dichroic plate to split light is proposed,and an optimization function for automatic de-occlusion,lightness,and miniaturization is constructed.This method was used to design an off-axis three-mirror four-channel optical system with spherical primary,secondary,and tertiary mirrors.For the ground image,the focal length was360mm,relative aperture was 1/6,field of view was 13°×5°,and working waveband was 0.4-1.1mm.The element resolution was 5m,and the distortion of the full field of view was less than 5%.The entire system installation and adjustment were completed according to the tolerance analysis results.After processing and installation,the measured modulation transfer function(MTF)curve of the100 lp/mm entire system was greater than 0.25.The system had good image quality and it occupied only 245mm×423mm and the entire weight was only 13.82 kg.This shows that the system had excellent characteristics of a large field of view,no obstruction,lightness,and miniaturization.