Design of Laser Projection Display Illumination System Based on Freeform Surface Array

The projection products of pure laser sources arc one of the future trends in the development of display technology. In order to use multiple laser diodes as the light source to achieve high power uniform illumination, a laser illumination system is designed in this paper. Two lenses and a round rod arc added before the uniform illumination system based on the freeform surface array to further improve the uniformity of target surface. The laser array is collimated and then converged into a round rod for transmission. After being collimated by the lens, it passes through the freeform surface array and is converged on the target surface by the field lens to form a uniform illumination area. With the help of software simulation, it is found that the uniformity of the target surface increased from 77.59% to 90.99% after mixing the light with the round rod. In addition, the shape of the freeform array unit is studied. The experimental results show that, compared with the square structure unit, the freeform surface unit with the same aspect ratio as the target surface can get better uniformity.