基于衍射光学的大视场卡塞格林光学系统设计

Design of Cassegrain Optical System with Wide Field of View Based on Diffractive Optics

为了改善卡塞格林光学系统的视场,将衍射透镜成功地引入大视场卡塞格林光学系统的设计中,并给出了设计方案。该系统在次镜后使用了2个校正透镜,且第1个透镜的前表面具有衍射面,能在3.6°视场内获得接近衍射极限的成像质量,各视场的波前差均小于1/4波长,光学传递函数(MTF)接近衍射极限。设计结果表明,衍射光学元件(DOE)对于改善卡塞格林系统的视场具有重要的作用,此设计方案降低了对加工工艺的要求,大大降低了成本,结构紧凑且具有良好的消像差特性。

To ameliorate the field of view Cassegrain optical system,a diffractive optical element（DOE） is successfully intro- duced to the system and the design scheme is provided in this paper. Two correcting lenses with a diffractive surface on the front surface of the first lens are placed after the second reflecting mirror in this Cassegrain system. This system could achieve fine imaging quality that approaches the diffraction limit over 3.6° field of view,and the wave-front aberration of each field is less than 1/4 wavelength,so that the modulation transfer function（MTF） is approached to the diffraction limit. The results of the design show that DOE has a great effect on ameliorating the field of view of the Cassegrain optical system. The design scheme reduces the demand for high technical levels and cost, and has a compact structure and better aberration character.