Research On White Light Source Based On Laser Remote Excitation Phosphor Technology

In recent years,with the advent of blue laser diodes,laser illumination is expected to become possible.The new generation of solid-state lighting technology with subversiveness has become a hot spot for countries to study.Laser white light has higher brightness than traditional LED white light.A series of advantages,such as long life and stable work,this paper aims to study a technology based on laser remote excitation of phosphors,which provides a theoretical basis for the packaging and design of subsequent LD white light products.In this paper,by analyzing the technical principle of laser white light illumination,it is decided to obtain the white light source by laser remotely exciting the phosphor.The excitation light source used in this scheme is a 450 nm blue laser diode.The fluorescent material is selected from YAG yellow phosphor and matched with a nitride red phosphor to improve the color rendering of the light source.The encapsulant is made of epoxy resin with higher refractive index.The main research work of LD white light source is as follows:1.The effects of laser divergence angle,laser power density and laser modulation frequency on the excitation efficiency of the phosphor were investigated.It can be concluded that the elliptical spot emitted by the laser can effectively improve the illuminating quality of the laser white light after being shaped into a nearly circular spot by fiber coupling;by increasing the power density of the laser,the excitation efficiency of the phosphor can be improved at the laser power density.When the voltage reaches 0.5w/mm^2,the excitation efficiency remains basically unchanged;when the modulation frequency of the laser increases to 12 Hz,the laser luminescence can be regarded as a continuous type,and the conversion efficiency of the phosphor is basically stabilized at a fixed value.2.The scattered light before and after the phosphor layer was studied,and the transmitted light intensity and uniformity of the backscattered light were better than forward scattering.By adding a mirror after the phosphor sheet,the backscattered light color quality is better.3.Based on the Mie scattering theory,the effect of phosphor concentration on white light source is studied.It is found that the average color temperature and luminous flux of forward scattering decrease with the increase of phosphor concentration,while the backscattering remains basically unchanged.The experiment also improved the color rendering index by adding a nitride red phosphor.After the proportion of red powder reached 2%,the color rendering index would exceed 80.4.In order to realize the specific application of LD white light,two phosphor package models and a laser white light source module were designed.In this paper,the BMW headlight model is designed based on Lighttools,and the Monte Carlo collimation function is optimized to obtain a beam with uniform light intensity distribution and good collimation.