针对头盔显示器质量小、尺寸合适及结构紧凑方面的需求, 利用离轴折/反射式原理设计一款头盔显示器光学系统, 采用单片式自由曲面棱镜解决出瞳直径小的问题。设计的系统参数如下：出瞳直径8 mm, 视场角20°(H)×15°(V),出瞳距离20 mm, 配合0.47 in的OLED-XLTM显示屏, 显示区域9.6 mm×7.2 mm, 像素数640 pixel×480 pixel, 像元尺寸15 μm×15 μm。采用单个元件设计, 体积小于13 mm×25 mm×17 mm, 所用材料为K26R, 在30 lp/mm时全视场调制传递函数大于0.25。该系统采用单个元件设计, 兼顾成像质量的同时, 使光学系统的体积和质量更小。

The helmet-mounted display demands light weight, suitable size, and compact structure. Aiming at the demands, we use the off-axis catadioptric principle to design a helmet-mounted display system, and the monolithic freeform surface prism is utilized to solve the problem of small exit pupil diameter. The designed system parameters are as follows: the diameter of the exit pupil is 8 mm, the angle of field of view is 20°(H)×15°(V), distance of exit pupil is 20 mm, a 0.47 in OLED-XLTM display is selected, the display area is 9.6 mm×7.2 mm, the pixel number is 640 pixel×480 pixel, and the pixel size of 15 μm×15 μm. A single element is adopted to design the system, whose volume is less than 13 mm×25 mm×17 mm. K26R is selected. The modulation transfer function at 30 lp/mm in the full field of view is higher than 0.25. The system is designed with a single element, and realizes small volume and light weight with imaging quality taken into consideration.