针对制冷式大面阵640×512凝视焦平面阵列探测器, 设计了一套中波红外连续变焦光学系统。该系统由变焦系统和二次成像系统构成, 包括7片透镜和2个反射镜组成的折叠光路。首先, 根据变焦原理和专业光学设计软件给出了系统结构及其参数。然后, 分析了系统的像质和冷反射效应。最后, 验证了系统的性能指标。结果表明：该系统可以实现50～500 mm的连续变焦, 变焦过程中目标景物始终清晰可见; 系统在耐奎斯特频率处的全视场光学传递函数大于0.35, 全视场畸变小于2%, 无冷反射现象; 具有分辨率高、热灵敏度高、像质好、变焦轨迹平滑等特点, 基本满足设计要求。

A mid-wavelength continuous zoom optical system was presented for a staring Focal Plane Array(FPA) infrared detector by cooling assembly. The optical system with an optical configuration of reflect mirror fold was composed of a zoom object lens system and a secondary imaging system including seven lenses and two reflectors. On the basis of zoom principles, the systemic structure and design parameters were given by using special optical design software, then the schematic diagram and imaging quality were investigated. Finally, the performance and indexes of the system were verified. The results indicate that the system can offer a 50-500 mm continuous zoom and 100% cold shield efficiency. Moreover, the Modulation Transfer Function (MTF) in whole fields at Nyquist frequency is over 0.35 and the whole field distortion is below 2%. These results show that the system is characterized by high resolution, thermal sensibility, excellent images and smooth zoom locus.