通过推导两个波段间由于色散特性差异导致的波段间色差，得到了描述波段间色散能力的波段间色差系数P，并结合光学系统光焦度方程、消色差方程和消热差方程，讨论了考虑材料波段间色散能力的消热差色差系统设计方法，完成了一个共光路红外双波段双视场光学系统的无热化设计。该系统F 数为2、焦距为150 mm/50 mm、波长范围为3.7~4.8 μm 和7.7~10.3 μm，共含有8 片透镜，3 个非球面，在-40 ℃~60 ℃温度范围内，各视场均具有较好的成像质量和冷反射特性。

The between- band chromatic dispersive power P is derived from the derivation of between- band chromatic aberration. A new achrothermal model considering the between-band chromatic aberration is prompted. Then, method of athermalized and multi-band zoom optical system is discussed. Based on this achrothermal model, a dual-band (MWIR/LWIR) dual-field of view optical system under the requirements of F=2, 150 mm/50 mm focal length, 3.7~4.8 mm and 7.7~10.3 mm waveband is designed with optical passive athermalization technology. The optical system, which consists of 8 lenses and 3 aspheric surfaces, has good image quality and Narcissus character at each field of view at -40 ℃~60 ℃.