基于车载观瞄模拟系统的使用要求，根据高斯光学设计理论，运用Zemax光学设计软件设计了一种三组元变焦目镜。为了获得较好的像质及长出瞳距，目镜结构采用三组元结构。同时，为了使目镜在连续变焦时入瞳位置保持不变，将出瞳位置设为变量进行优化。最终设计结果为：焦距f=13.35 mm～24.11 mm，出瞳距离L=20.1 mm～27.5 mm,出瞳直径D约为8 mm，像面变化范围y′=4.6 mm～13.6 mm，变焦目镜变倍比约为1.83倍。在50 lp/mm时，4个组态MTF均大于0.3，且各组态点列图均小于艾利斑半径，高于人眼分辨极限，满足使用要求。最后利用Matlab软件编写程序进行曲线拟合，给出了三组元之间的3个间距和所对应系统焦距的变化曲线，拟合精度达0.01 mm。

Based on the operation requirements of an vehicle-borne observation and sighting simulation system and Gaussian optics theory, a three-group telescope zoom eyepiece was designed with Zemax. In order to obtain better image quality and long exit pupil relief, a three-group structure was adopted, and the pupil position was set as an optimized variable to make the entrance pupil position unchanged for continuous zoom. The focal length is f=(13.35～24.11) mm, exit pupil relief is L=(20.1~27.5) mm, exit pupil diameter is about 8 mm, image plane range is y′=(3.9～14.06) mm, and zoom ratio of telescope zoom eyepiece is1.83. At 50lp/mm, the MTFs of four configurations are greater than 0.3, the spot diagrams of all configurations are smaller than Airy disk radius and higher than human eye resolution limit, which meet user requirements. Finally, the curves are fitted by Matlab, the corresponding focal length curves are given, and the fitting accuracy reaches 0.01mm.