Optical System Of Integrated LED Automobile Headlamp With Asymmetric Double Freeform Surface

With the continuous improvement of production and package technology of LED,LED light sources are widely used in various fields of illumination,especially in the field of automobile lighting.Since the intensity distribution of LED is different from that of the traditional source,it is necessary to design secondary optics for LED illumination.What’s more,the existing optical systems of automobile headlamp include separate optical systems and integrated optical systems,which exists large volume,designing adaptive front-lighting system difficultly,low illuminance of high beam and other issues.So,to design the integrated LED headlamp with more compactness and higher illuminance is very significant.According to the theory of non-imaging optics and freeform surface,three methods of designing the integrated LED headlamp based on the asymmetric double freeform surface lens are proposed in this paper.Each optical system of integrated headlamp has its advantages and all illumination distributions fully meet the requirements of the national standard.The main steps of integrated headlamp design include illumination divisions in the target area,calculating the mapping relationship between the rays with certain angles and the points in the target area,calculating the discrete points of the asymmetric double freeform surface lens by iteration of the normal vector,importing the discrete points to the modeling software,optical simulations in the optical software,feedback adjustment according to the simulation results,obtaining the asymmetric double freeform surface lens model.The radiator is designed for each optical system.Besides,the finite element software is used in heat simulations to guarantee that the heat from the chips can dissipate well.Based on simulation results,optical samples are fabricated for two of the optical systems.The test system for the headlamp is used to test the performance of the integrated headlamp.The test results are very close to the simulation results,which meets the requirements of the national standard.At the same time,the color temperature on the target plane is stable.The volume of the optical system is reduced,and the illuminance of high beam is improved.The proposed three methods for the integrated headlamp design can be used in the field of automobile lighting.