航空相机的光学系统决定相机的外形尺寸,针对一个25 倍航空变焦镜头的光学设计指标要求,进行小型化设计。为缩短筒长,采用负组补偿偏离物像交换变焦结构,缩短变倍补偿系统各组元焦距,增加前固定组和变倍组间距的设计方案,通过解初级像差方程求得初始结构,依据像差理论,利用ZEMAX 自动设计软件进行像差校正平衡。设计结果表明,该系统可以实现20～500 mm 的连续变焦,筒长只有198 mm,中心视场传递函数值大于0.4,0.7 视场传递函数值大于0.2。

The dimension and configuration of aerial cameras is mainly determined by the optical system. A miniaturization design was made based on the requirement of a 25× aerial zoom lens. In order to decrease total optical length, a design scheme was employed by selecting mechanically compensated zoom lens with a negative compensator, shortening the focus length of variator and compensator, and increasing the distance between front group and variator. An initial configuration was obtained by solving equations of aberrations. According to aberration theory, the aberrations were corrected by using ZEMAX optical design software. The result indicates that the focusing length can vary from 20mm to 500 mm continuously for this system, the optical total length is only 198 mm, and the Modulation Transfer Function (MTF) values are higher than 0.4 at 0 field and 0.2 at 0.7 field respectively.