高分辨率红外成像仪五反无焦主系统设计

为提高多通道红外成像仪的空间分辨率,同时确保系统结构紧凑,具有良好的轴对称性,设计了应用于像方扫描主系统的主镜轴对称的五反无焦系统。论述了基于初级像差理论的五反无焦系统设计方法,由各镜面之间的放大率和遮拦比求解出了结构参数,利用初级像差系数求解出了反射面二次曲面参数,并且编制了初始结构计算程序。设计了一个入瞳直径1 m、视场50.1、工作谱段8~10 m、口径压缩倍率10的五反无焦系统。设计结果表明:光学系统最大波前差RMS值优于0.065(=9 m),最大光程差优于/4(=8~10 m),各视场的MTF曲线接近衍射限。该设计方法可广泛应用于高分辨率多通道成像仪的光学系统设计。

Design of five-mirror afocal principal system for high spatial resolution infrared imager

In order to increase spatial resolution, five-mirror afocal optical system with axial-symmetric primary mirror was designed, which was used for principal system of image space scanning system. The system was well compact and axial-symmetrical. The method of five mirror afocal system design based on primary aberration was explored. The structural parameters were calculated according to magnification and obscuration ratio of each mirror. The conic parameters were calculated according to primary aberration coefficient. The procedure for calculating initial structural parameters was programmed. Then a five-mirror afocal system was designed with an entrance pupil diameter of 1 m, a field of view of 50.1, the operating wave band of 8-10 m, compression ratio of 10 times. The results indicate that the maximum root mean square (RMS) wavefront error is less than 0.065(=9 m), the maximum optical path difference(OPD) is less than /4(=8-10 m). It has high imaging quality and the modulation transfer function (MTF) is approached to the diffraction limit. The method of afocal system design can be widely used for high spatial resolution multichannel imaging.