基于同轴三反射光学系统基本原理，将孔径光阑和视场适当偏心，设计了一个灵巧型多光谱离轴三反光学系统，系统焦距1 200 mm，并对设计结果进行了像质评价。实验结果表明：系统在可见波段（0.486 μm ~0.656 μm）80 lp/mm空间频率下MTF>0.5，中波波段（3 μm ~5 μm）15 lp/mm空间频率下MTF>0.35，全波段范围内最大RMS为2.096 μm。系统中面型采用二次非球面，且整个系统仅有孔径光阑偏心，3个反射镜位置均无偏心和倾斜，降低了加工成本及装调难度。

Based on the theory of coaxial three-mirror reflective optical system and by decentering the aperture stop and the field of view, a compact and multispectral off-axial three-mirror reflective optical system with 1 200 mm focal length was designed. Furthermore, the image quality was evaluated. The design results prove that the modulation transfer function(MTF) is above 0.5 at 80 lp/mm for 0.486 μm ~0.656 μm, above 0.35 at 17 lp/mm for 3 μm ~5 μm and the root-mean-square (RMS) radius is less than 2.096 μm in full waveband. Moreover, three mirrors which use cone surfaces instead of high order aspherical surfaces are not decentered or tilted and only the aperture stop is decentered, so it is easy to fabricate and assemble.