基于硫系玻璃的汽车夜视折衍光学系统

Design of Refractive-Diffractive Night Vision System Based on Chalcogenide Glass

在夜间或雨雪、大雾天气等能见度低的情况下，利用传统的汽车照明系统，驾驶员较难看清前方的景物及行人。夜视辅助驾驶系统可以提高驾驶员夜间行车视距，减小交通事故发生概率。基于硫系玻璃的汽车夜视系统应用越来越广。分析比较了目前市场上存在的几类夜视光学系统的优缺点，设计了基于新型红外硫系玻璃和衍射光学元件的夜视系统，优化后系统的视场角为30°、焦距为15mm、F数为1、工作温度范围为-30℃～50℃。系统包含三片材料为Ge20Sb，sSees的透镜，仅引入一个非球面和一个衍射面。实验结果表明，在空间频率15lp／mm处，系统的调制传递函数接近衍射极限，在-30℃～50℃温度范围内最大的焦移量为6．6μm，远小于系统焦深20Mm，成像质量良好。

The illumination of cars is limited when they run at night or under other low visibility situations. The drivers have difficulty in seeing the scene and pedestrians in front, which greatly increases the risk of driving. Night vision system based on chalcogenide glasses is more and more used in automotive industry. The advantages and disadvantages of night vision systems are analyzed. A novel optical system based on chalcogenide glass and diffractive optical elements is presented. A diffractive-refractive hybrid night vision system with 30° field of view is designed. The effective focal length and F number are respectively 15 mm and 1. The system is composed of three lenses which use Ge20 Sb15 Se65, including a conic surface and a diffractive surface. The experimental results show that the modulation transfer function （MTF） of the hybrid system is close to diffraction limit at the spatial frequency of 15 lp/mm. The maximum focal shift is 6.6 /μm in the range from -- 30 ℃ to 50 ℃ , which is less than the system focal denth of 20 μm. The system has a compact structure and a good imaging quality.