针对制冷型320×256凝视焦平面阵列探测器, 设计了一套4倍中波红外连续变焦光学系统, 用于轻型机载光电探测和跟踪吊舱设备。该系统由变焦物镜系统、二次成像系统和2个反射镜构成, 为了避免非球面的加工及检测误差影响, 本系统只使用球面。设计结果表明, 系统实现了37.5 mm～150 mm的连续变焦, 工作波长范围为3.7 μm～4.8 μm, F数为4, 满足100%冷光阑效率, 系统在探测器的Nyquist频率16 lp/mm处, 所有焦距位置和视场的MTF均大于0.55, 接近系统的衍射极限。该变焦系统总长280 mm, 质量仅为110 g, 具有体积小、质量轻、分辨率高、变焦轨迹简单等优点。

Aiming at the cooled 320×256 detector with staring focal plane array (FPA), an optical system of middle infrared continuous zoom system was designed for airborne optoelectronic detection and tracking apparatus. The system was composed of a zoom lens system, a secondary imaging system and two reflectors. In order to avoid the fabrication and testing error of aspheric surface, the whole system was made of nine spherical glasses. The design results indicate that the system achieves the continuous zoom of 37.5 mm~150 mm, with working length of 3.7 μm~4.8 μm, and F number of 4, which can obtain the cold shield efficiency of 100%. At the Nyquist frequency of 16 lp/mm, the MTF values of all focal length positions and field of view are more than 0.55, which are closing to the diffraction limit. The overall lens length is 280 mm and the weight is only 110 g. The optical system has the advantages of small volume, high image quality and simple structure.