利用镜面形变实现共轴折反射式变焦光学系统设计

在光学系统中加入2个或多个可变光学元件,保持光学元件位置不变,通过微调装置改变这些可变光学元件的焦距使得整个光学系统的有效焦距发生变化。基于该设计思想,结合卡塞格林(Cassegrain)反射式望远镜结构模式,使用ZEMAX光学设计软件设计了焦距为1 600 mm～800 mm,视场0.6°～1.2°的变焦系统,整个系统由2个可变形反射面、1个平面反射面和1个透镜组成,主要通过主镜和次镜面型曲率(可变形镜DMs,Deformable Mirrors)以及入瞳直径的变化实现系统变焦。设计结果表明:系统在空间频率16 lp/mm处调制传递函数大于0.75,最大均方根弥散斑半径均小于探测元尺寸,满足成像要求。

Design of coaxial catadioptric zoom system using deformable mirrors

In order to change the focal length of optical zoom system without using moving parts, two or more active optics were added, which could provide variable focal length and create an imaging system with variable magnification. Based on this design concept and combined with Cassegrain reflective telescope, a zoom system was designed with active optical elements in ZEMAX. Its effective focal length is from 1600mm to 800mm, and its field of view (FOV) is 0.6°～1.2°. The whole system consists of 2 reflective deformable mirrors, 1 fold mirror and 1 refractive lens. In order to achieve zoom function, the entrance pupil diameter, the first and the second reflective mirror’s radius are variable. Its MTF at the spatial frequency of 16lp/mm is more than 0.75, the maximum RMS spot diameter is less than detector size. The results show that the imaging quality can satisfy system requirements.