Optical design of super miniature Micro-LED projection

With the emergence and development of self-luminous micron-pixel-sized Micro-LED (Micro light-emitting diode, mu LED),using mu LED as the light and image source have become possible for ultra-compact projection optical engines. It greatly simplifies the structure of traditional projection display optical engines. In this paper, a mu LED-based super miniature projection optical engine is proposed,and a high image quality pico-projection lens is designed based on 3. 302 mm(0. 13 in) mu LED display chip. The divergence angle of mu LED display chip matched with the pupil of pico-projection lens is optimized according to the light distribution characteristics of mu LED chip,which effectively improves the light efficiency of mu LED based pico-projection optical system. The results show that the volume of the system is only 18. 35 mm(3),and the MTF value of the center field of view of the projection lens exceeds 0. 57 at the cut-off frequency. The mu LED based pico-projection display optical engine achieves a good trade-off between system volume and image quality,and has a wide application prospect in near- eye display devices such as AR/VR in the future.