针对常用汽车 LED 投射式照明系统近光灯光能利用率低的问题，根据非成像光学原理，研究了 LED 近光灯近光配光特性与光源光能量、光学自由曲面透镜参数之间的关系，在此基础上提出基于微元能量映射的 LED 汽车近光灯自由曲面透镜设计方法．为了验证该方法的可行性，利用切面迭代曲面构型法 Rhino 软件设计了汽车 LED 近光灯透镜，运用 Tracepro 光学软件构建了汽车 LED 近光灯照明系统，然后对该系统进行了计算机仿真．结果表明，所设计的 LED 近光灯自由曲面透镜产生的光型不但能满足近光灯法规要求，而且光能利用率较常用的汽车 LED 近光灯照明系统提高 23. 5%．

In order to improve the luminous energy rate of dipped headlight in the LED projection headlamp systemcommonly used in vehicles,the relationships between the lighting distribution of LED dipped headlight and the lightsource energy as well as the freeform lens parameters were investigated based on the theory of non- imaging optics,and a design method of LED freeform lens for vehicle dipped headlight was proposed based on the infinitesimalenergy mapping.Then,in order to verify the feasibility of this design method,a LED lens was designed with thesoftware Rhino,and an illumination system of LED dipped headlight was constructed with the software Tracepro.Simulated results indicate that the designed lens not only provides illumination patterns matching the dipped head-lamp regulation but also possesses a luminous energy rate increment of 23. 5%,as compared with the traditionalLED projection headlamp system.