从系统焦点不引出主镜背后的格里高利系统出发,偏瞳后在其一次像面处加球面反射场镜来校正畸变等像差,并采纳了折轴三反射系统的结构优点,设计出一种新型无遮拦三反射光学系统。分析了该种系统的设计步骤,设计了一个焦距为900 mm,视场为0.8°×0.8°,F数为9的光学系统,总长为330 mm,成像质量接近衍射极限,具有较小尺寸、较好的杂散光抑制能力等特点。该系统与其他三反射光学系统相比,最大的优点是非球面反射镜只用了两块,降低了成本和加工装调难度。

One new-style unobscured three-mirror optical system was designed,which was based on the Gregorian system. The design step of this special three-mirror optical system was analyzed,and then a system with effective focal length of 900 mm,field of view of 0.8°×0.8° and F-number of 9 was designed. Its total length is 330 mm. The image qualities of the example are near diffraction limit. The system has advantages of shorter physical size and better ability in restraining stray lights. Compare with other three-mirror optical systems,the most prominent advantage of this special three-mirror optical system is that it just uses two aspheric mirrors and one spherical,thus reducing the cost and the manufacturing difficulties a lot.