小卫星具有研制发射成本低、适于机动战术应用等优点，但基于几十kg级的卫星平台实现米级或亚米级对地光学遥感，仍是一个具有挑战性的问题。对此提出一种新的两反射镜折反系统，由两块非球面反射镜和像方负光焦度三透镜组组成，兼具传统两反射镜系统轴对称性而结构紧凑、易于装调和三反射镜系统平场消像散的优点。首先，介绍该新型系统基本思想与结构，导出其初级像差公式，分析给出色差和单色像差校正方法与初始结构求解方法。然后，实例优化设计得到结构紧凑、适用于低轨高分辨率小卫星对地遥感的光学系统，其工作波段、全视场角、有效焦距和F数分别为450~800 nm、1.2°、3000 mm和F/10，系统的光学总长和通光口径分别为595 mm和300 mm。自身消色差的负光焦度透镜组由同种普通玻璃组成，系统成像质量接近衍射极限。

Small satellites had the advantages of low-cost and being suitable for flexible tactics application. But it was a challenge to realize optical remote sensing in meter or sub meter level based on satellite platform which weight dozens of kilograms. A new two-mirror catadioptric system which consisted of two aspheric mirrors and a negative focal power group with three lens was proposed. This system was coaxial as traditional two-mirror system. Then the structure was compact and installation would be easy. At the same time, the system had flat filed and was anastigmatic as three-mirror system. At first, basic idea and structure of the new system were introduced, its primary aberration formula was derived, the means for correcting its aberrations including chromatic aberration was analyzed and presented, and thereby its initial structures were solved. Then, An example which had compact structure and was suitable for optical system on low-orbit high-resolution small satellite was designed and optimized. Its work band, full field of view, effective focal length and F-number were from 450 nm to 800 nm, 1.2毅, 3000 mm, F/10. Length of the optical system and the stop were 595 mm and 300 mm. Negative focal power lens group corrected chromatic aberration by itself, and three lens used same common glass. Imaging quality of the system was diffraction-limited.