与传统定焦系统相比，红外双焦光学系统具有宽视场搜索目标、窄视场跟踪目标的能力；与连续变焦系统相比，红外双焦光学系统机械结构简单，装调容易等优点成为近年来研究的热点。介绍了一种用于324×256中波致冷红外探测器双焦10×光学系统设计结果。系统焦距24～240 mm，F#2，采用切入式变焦方式，短焦宽视场的全视场角达到28.7°；长焦窄视场的全视场角仅为2.9°。二次成像技术的应用，可以有效的减小轴向尺寸。Code V光学设计软件进行优化得到在空间频率17 lp/mm处，宽视场和窄视场的MTF均大于0.5。

Compared with single-focal length optical system, infrared dual-zoom optical system has capabilities such as searching targets in the wide field of view and tracking targets in the narrow field of view. Compared with the zoom system, infrared dual-zoom optical system has advantages, such as simple structure, easy fixing and so on, and becomes the hotspot of researches lately. Ten-times dual-zoom optical system for 324×256 midwave cooled detector is introduced in the paper. The focal length is 24 mm-240 mm, F#2. The manner of zoom was accomplished by inserting lenses. In the wide angle mode, the field of view was 28.7°. In the narrow angle mode, the field of view was 2.9°. The technology of re-imaging was used to reduce the axes size of optical system. The system is optimized with coed V optical design software and the MTF greater than 0.5 at WFOV and NFOV in the spatial frequency 17 lp/mm.