Research On Automobile Headlamp Based On Laser Light Source

Laser has the advantages of high energy density, good directivity and so on. Laser headlamp which using laser as the light source of automobile headlamp also has the merits of high brightness and long distance. As the developing direction of auto mobile headlamp, the study of laser headlamp has already matured abroad, but it still stays in the start stage in the domestic, thus study of laser headlamp has the great practical significance and research value.The main work of this paper is using monochrome laser source to synthesize white laser source which can meet the color requirement of national standard. Then according to the emitting characteristics of white laser source, the free form lens of laser headlamp which can achieve the lighting requirement of national standard is designed.Firstly, the colorimetric characteristics of laser headlamp is researched and the method of using 450nm blue laser to excite YAG yellow phosphors is proposed. In this paper, we designed the system of laser headlamp, the color temperature and illumination of laser headlamp meets the national standard. Through contrastive analysis of several methods of white light, the 450nm blue laser light source is selected. According to the principle of light color melange, it is required to use the edge of the saturated color in CIE coordinates as the standard of synthetic white light. By studying the light scattering mechanism of blue laser exciting yellow phosphor piece, three different structure is designed and analyzed, it is concluded that in the transmission structure, the blue light is more likely to be mixed with the scattering yellow light, and forms the better white color. The molarity of phosphors is also studied, the result of 20 groups of simulation shows that when the concentration of phosphor is 3.565 ×10-4mol/L, the color temperature is the best.Then, based on the high energy density and narrow beam characteristics of laser source, the free-form surface lens which can achieve the positioning beam expander and solve the issue of high energy density and narrow beam is designed. Using Monge-Ampere equation which has nonlinear boundary conditions, the coordinate relations between free-form lens and receiving screen is built, newton second order finite difference method and MATLAB software is used to calculate the discrete coordinates on the lens surface, Pro/E is used to fit the free-form surface.Finally, the designed model of laser source and free-form lens is analyzed in TracePro. The result shows that when the distance between the source and free-form is among the scope of 1.4～3.4mm, the illumination of each test point and area on the receiving screen can meet the requirement of automobile headlamps national standards. When the distance between light source and lens is 1.4 mm, the average illumination is highest light and the light energy is most concentrated.