将一个同轴三反系统和两个离轴三反系统相结合，设计了同离轴混合式三反光学系统。同轴系统视场角为1°×0.1°，F 数为7.3，工作波段为0.38~0.78 μm 和1.2~1.7 μm；离轴系统视场角为2°×0.1°，F 数为18.9，工作波段为0.38~0.78 μm。两系统焦距同为14 m，可同时推扫成像，均具有中间像面和实际出瞳，便于抑制杂散光。优化后，像质均接近衍射极限，各视场、各波段奈奎斯特频率处调制传递函数均大于0.41，满足静态传递函数优于0.2的系统设计要求。全系统结构紧凑，易于加工和装调。

One coaxial and off-axial hybrid three-mirror optical system is designed, by combining a coaxial threemirror system and an off-axial three-mirror system. A 10×0.1° field of view (FOV) is achieved by the F/7.3 coaxial system with spectral coverages of 0.38~0.78 μm and 1.2~1.7 μm. A 2°×0.1° FOV is achieved by the F/18.9 off-axial system with spectral coverage of 0.38~0.78 μm. The above two systems have the same focal length of 14 m, and the simultaneously performing push-broom imaging ability. They both have a middle image plane and a real exit pupil which can supress stray light easily. After an optimization, near diffraction-limited performance can be obtained over all the FOVs and the spectral ranges. A minimum modulation transfer function (MTF), higher than 0.41 at Nyquist frequency, is acquired, which satisfies the design requirement to achieve a static MTF higher than 0.2. Moreover, the whole system structure is compact and its elements are easy to manufacture and align.