Highly efficient and ultra-compact micro-LED pico-projector based on a microlens array

Pico-projection displays are the main developing direction for future projection displays, but the balance between the optical efficiency and the system size is still a big concern. This paper presents a pico-projector design based on micro-LED (mu LED) light sources. Firstly, based on the analysis of the characteristics of mu LED, a highly integrated microlens array is designed to improve the system efficiency by reshaping the spatial light distribution. In addition, the matching relationship between the aperture angle of projection lens and the divergence angle of mu LED is studied, and on this basis, a set of four-piece spherical lens group is proposed to achieve compact size. Simulation results show that the mu LED equipped with the microlens array can concentrate about 86% of the light energy within a dispersion angle of +/- 20 degrees, thus increasing the light energy utilization by about 3.5 times and reducing the size of the pico-projector to 30.18 mm(3). The designed pico-projector has high performance and compact size with great potential for future applications.