针对切换式红外光学系统的长焦部分单独成像，切入一组透镜后实现短焦部分成像的特点，提出了一种对切换变焦系统的长短焦部分分别进行热补偿的方法。在-30～+70 ℃范围内，移动长短焦共用透镜组实现对长焦的热补偿，对此时短焦系统剩余的热差，移动短焦切换组元来实现其热补偿。设计了一个焦距180/60 mm，8～12 μm，F数为2的切换变焦系统。分析了系统在不同温度时的像质，两个补偿透镜组的位移量及其数值关系。用Diffsys软件对系统中使用的衍射元件的特性进行了分析。此系统的长短焦不需要考虑各种材料搭配，较好地实现了热补偿。

A method of temperature compensatory for switching zoom system is analyzed in this paper. The wide field-of-view of the switching zoom system is usually provided by inserting some extra lenses in the narrow field-of-view of the system at an appropriate location. So the long EFL of this system achieve the best temperature compensation by moving the mutual compensated lens, and the short EFL of the system achieves the best temperature compensation by moving the switching compensated lens and the mutual compensated lens simultaneously. A DFOV switching zoom system is designed. It has a relative aperture of F/2.0, the EFL of 180 mm/60 mm at 8~12 μm. The MTF and the distance of the compensated lens of the system are analyzed. The characteristics of the diffractive optical element are analysed in the software of Diffsys. So the long EFL and short EFL of this system achieve the best temperature compensation without considering material arrangement.