Design of RGB LED colour-mixing optical system based on double-layer random microlens array

The high quality mixed white light is widely used in some fields of illumination of machine vision and optical projection. Optical design can improve white light production using RGB LEDs mixture method. In this paper, a kind of optical design method based on double-layer random microlens array is proposed for better white lighting. The design effect is verified by some comparisons with the double-layer non-random microlens array system. Experimental results show that the normalized standard deviation of white point shift is decreased from 0.05 to 0.01, the average colour difference is decreased from 44 to 2.5, and the illumination uniformity is increased from 0.66 to 0.82. The proposed design method can eliminate the incomplete overlap of rays and colour shadow effectively, and the proposed optical system design method can solve the problems of white point shift, colour difference, uniformity in mixed white light illumination.