长波红外变焦系统的设计与研究

Design and research of long wave infrared zoom system

文章基于一款专利US4148548A的初始结构,利用光学设计软件CODE V研究设计了一套结构简单的长波红外变焦系统。为简化结构、消除像差,系统增加了非球面设计,并从场曲、畸变以及调制传递函数(modulation transfer function,MTF)等方面对系统的像质进行评价。评价结果表明,系统在各个焦距时的畸变基本为0,场曲在允许的范围之内,MTF值在极限频率时达到了0.5以上。结合应用与实际生产,对系统MTF值进行了公差分析,得到MTF值在0.4以上的概率达到99%。

Based on the initial structure of a reference patent US4148548A and the use of CODE V as optical design software, the long wave infrared zoom system with simple structure is researched. To simplify the system structure and eliminate aberration, the aspheric surface design is added, and the system image quality is evaluated in view of field curvature, distortion and modulation transfer func- tion（MTF）. Through the image quality evaluation, it is found that the distortion in various focal lengths is almost equal to zero, the field curvature is also in the permitted range, and the MTF value in the limit frequency reaches more than 0. 5. Based on the application and actual production, the tol- erance analysis of MTF value in the system is given, showing that the probability of MTF value above 0. 4 is 99%.