设计了在相同光学引擎、相同屏幕位置下, 能满足不同屏幕尺寸需要的变焦投影物镜。该变焦投影物镜的焦距变化范围为22 mm~37 mm, 视场角为46°~75°, F数为2.8。考虑设计的光学系统要求相对孔径较大, 具有大视场角和小变焦倍比, 根据变焦理论, 采用正组补偿的机械补偿法, 并对变倍组、补偿组进行合理的倍率选段, 求出高斯解; 然后对各组元分别选用合理的初始结构, 利用Zemax光学设计软件进行优化设计, 适当添加非球面。采用二、四组元运动的机械补偿法解决了大视场变焦系统畸变难以控制的问题, 并利用调制传递函数综合评价了整个光学系统。设计结果表明: 该变焦投影物镜系统的光学结构和成像质量均符合设计指标要求, 在空间频率64 Lp·mm-1处调制传递函数(MTF)值均大于0.3, 畸变小于1%。

Zoom projection lens are designed to meet requirements of different screen size with same optical engine and screen position. Focal length of zoom projection lens ranges from 22 mm to 37 mm, viewing angle is 46° to 75°,and F number is 2.8. Considering design of optical system requiring a relatively large aperture, with large field of view and small zoom ratio, according to zoom theory, positive mechanical compensation configuration is adopted, reasonable magnifications of zoom configuration are chosen and Gauss roots are derived. Appropriate primal configurations based on each subassembly are chosen. Optimization design is carried out with Zemax optical design software, and added proper aspheric surface. Mechanical compensation method of two and four component motion is used to solve problem that distortion of large field of view is difficult to control, and whole optical system is evaluated synthetically by using modulation transfer function (MTF). Design results show that optical structure and image quality of zoom projection objective system meet design requirements. Spatial modulation transfer function (MTF) value is more than 0.3 at spatial frequency of 64 lp·mm-1, and distortion is less than 1%.