紧凑型大变倍比红外光学系统设计

针对常用变焦结构在实现大变倍连续变焦时存在的各类问题，从变焦系统设计的基本理论出发，提出了一种可用于大变比光学系统设计的两级串联变倍模型，给出了相应的变焦方程及凸轮曲线设计的优化控制条件和方法。该模型由两组元连续变焦前组和具有变倍放大功能的二次成像后组串联组成，通过移动前组中的变倍组与补偿组实现一级变倍；通过移动补偿组与二次成像组中的二级变倍组，对前组焦距进行二级放大，扩大整个成像系统的变倍能力，同时，二次成像组还压缩了物镜口径，保证了冷阑匹配。完成了一个大变比连续变焦光学系统设计，该系统工作波段为3.7~4.8 m，采用640480制冷型面阵探测器，像元大小15 m，F数恒定为4，可以实现6.5~455 mm、水平视角0.92~58.2、达70倍的连续变焦功能，仅采用了两种材料，十片透镜，总长300 mm，具有优良的成像质量和公差特性。

Design of compact high zoom ratio infrared optical system

In order to solve the problems in high zoom ratio lens design, a two-stage-of-series zoom lens model was proposed based on optics zoom theory. Therefore, differential zoom equations were deduced and solved to help the lens power assignments, also the cam curve optimization condition and method were proved. In this model, first stage zoom was achieved by the two-part-zoom front part, and the given movement pattern of the compensation lens and the second magnified lens determined the second stage zoom, by which the 100% cooled stop efficiency was assured. Based on this method, a 70x MWIR zoom lens under the requirements of F/4, focal length 6.5-455 mm, HFOV 0.92-58.2, work waveband 3.7-4.8 m was designed, which only used two kinds of infrared materials, consisted of 10 lenses, total length 300 mm, had good image quality and tolerance character.