3片独立自由曲面式LED汽车近光灯光学设计

为了使车辆驾驶员在夜间能够得到充足的照明，并且避免对面会车司机眩目，设计了具有明暗截止线的近光系统。根据GB25991 2010汽车用LED前照灯配光标准，尝试使用大功率白光LED和结构简单、光学利用率高的自由曲面反射镜（FFR)来实现前照近光灯的设计。以非成像光学为理论基础，建立了LED光源出射光角度和照明面上坐标的对应关系，结合折反射定律计算自由曲面上点的坐标。合理划分基础面，并优化调整各子面的面型数据，实现配光要求。采用3颗LED共同实现近光功能，每颗LED均有各自独立的光学系统。测试结果表明:设计的光学系统效率达到54%，且近光截止线清晰，满足标准对各测试点照度的要求。

Optical design of 3 independent free form surface LEDs automotive dipped headlamp

In order to make sure of adequate lighting for the driver of the vehicle, and prevent the opposite driver from glare, an automotive dipped headlamp system with a cut off line was designed. A dipped headlamp according to GB25991 2010 light distribution standard (automotive headlamps with LED light sources/or LED modules) was designed with high power LED and free form reflectors (FFRs) which had simple structure and high optical efficiency. Based on the non imaging optics theory, the correspondence between the angle of the light reflected by the freeform reflector and the coordinates of point in the target plane was established. The freeform lens point coordinates were calculated according to the correspondence of reflection and refraction laws. To achieve light distribution requirement, the fundamental surfaces were divided legitimately and the surface profile data of sub surfaces were optimized and adjusted. The function of dipped headlamp was realized by 3 LEDs, each of which had its own independent optical system. The test results show that the optical system has a clear cut off line, with the efficiency reaching 54％, which can fully meet the requirements of the illumination of regulation on each test point.