Study On Color Uniformity Of Laser Projection Display

The light sources of traditional projection display system are mainly xenon lamps,LED(light emitting diodes)and other light sources.With the innovation and progress of semiconductor lasers,laser projection products began to be applied to the market.The characteristics of high laser energy density and good monochromaticity make the image quality better,but introduce new problems,so the lighting system needs to be redesigned.Now laser projection not only pays attention to brightness,but also other characteristics of the system,such as color uniformity,speckle,illumination uniformity,resolution and so on.The color uniformity problem is mainly caused by the lighting body,which leads to the uneven energy distribution of light in the lighting body.This paper mainly studies the influence of lighting body and diffuser on color uniformity.Firstly,three different structural schemes are designed according to the lighting main body.In the three primary colors,the dynamic / static diffuser of light source passing through different angles,types and positions is studied,and then the color uniformity of image is observed under the action of imaging system.The simulation results show that the best experimental effect can be achieved by using the combination of static diffuser 2Gauss 2 ° diffuser and dynamic Gauss 5.5 ° in position 2 in scheme 2.In position 2 in scheme 1,the combination of static diffuser 2 Gauss 2 ° diffuser and dynamic Gauss 5.5 °can also achieve the expected results.At the same time,with the support of three different design schemes,the experimental results show that the effect of design scheme 1 with diffuser 2 Gauss 2 ° is the best,and the color is lower than the target value of 0.015.In this process,the action principle of key optical elements is analyzed and the optimization system is designed with Light Tools software.Finally,in order to improve the brightness of the system,this paper further designs the LED system to form a hybrid light source.The influence of mixed light source on image color average quality is studied.According to the band-pass filter BPF(bandpass filter)spectrum,adjust the polarization state of the light source to let more LED light enter the system.The final experiment shows that the brightness of the three hybrid light sources is more than 30% higher than that of the three primary color laser system.Although the brightness is improved,it leads to the deterioration of color uniformity.Although scheme 1 with diffuser 2 and Gauss 2 ° is the best result,the data of the other two schemes show that there are serious problems in the quality of chromaticity uniformity and illumination uniformity.Then this paper analyzes the reason is that the divergence angle of LED system is large,which does not match with the three primary color system,resulting in uneven energy distribution.In the lighting system,the main homogenizing elements,light rod and convergent lens,can only work on the main light,but the edge light with large angle can not converge.The final experimental data also show that the edge light quality is the worst.To sum up,the color uniformity of the system is studied through three lighting system schemes,and improvement schemes are put forward to further guide and suggestions for future research work.The whole design of this paper requires that the system color is less than 0.015.In the experiment,whether it is three primary colors or mixed light sources,scheme 1 is equipped with a combination of dynamic diffuser 5.5 °and static diffuser 2 Gauss 2 ° to meet the requirements.The brightness of the three primary colors and the mixed light source reached 1206 lumens(LM)and 1516 lumens(LM)respectively,and the colors were less than 0.015.