根据所研制超光谱成像仪的性能指标和应用要求，设计可用作超光谱成像仪前置系统的连续变焦光学系统，具有相对孔径大、工作于可见光波段、中等焦长、光能利用率高和像方远心等特点。详细介绍变焦距光学系统的结构选型及其初始结构计算方法。设计的变焦距光学系统采用机械补偿法，变倍比为4×，相对孔径为1∶2，在宽视场（8°）和窄视场（2°）端的焦距分别为55 mm和220 mm。系统畸变小于0.6%，在66 lp/mm空间特征频率处的调制传递函数值大于0.5，能够满足超光谱成像仪的使用要求。

A continual zoom system, which can be used as the fore objective of the developed hyperspectral imager, is designed, according to the specification and application requirements of the imager. The lens have the advantages of high speed, visible light wavelength range, long effective focal length (EFL) high etendue and imagery telecentricity. The structural selection and the initial parameter calculation are introduced in detail. The designed zoom optical system with mechanical compensation is presented. The zoom ratio is 4×, and the relative aperture is 1∶2. The effective focal lengths are 55 mm and 220 mm respectively at short and long focus end, and the corresponding field of view angles from 2° to 8°. The distortion is lower than 0.6%. The modulation transfer function (MTF) value at the spatial frequency of 66 lp/mm is higher than 0.5. The designed zoom system can meet the application requirements of the hyperspectral imager.