Micro-LED Projection System Based on Compact Lens Group and Resonant-cavity

The growing demand for high-efficiency automotive projection displays highlights the limitations of conventional micro-LED, which exhibit lambertian emission profiles with wide divergence angles. Traditional projection lenses, with small apertures and large back focal ratios, result in poor optical coupling, making it difficult to meet brightness requirements. This study addresses this challenge by designing a projection lens with a larger aperture and smaller back focal ratio, enhancing coupling efficiency to 29.34% and reducing module size by 20%. The approach combines optical simulations and structural optimization, including Fabry-Pérot resonant cavity designs. A resonant-cavity LED (RCLED) incorporating a bottom Ag reflector and DBR reduces the divergence angle to 32°. This work provides a compact optical solution that improves Micro-LED coupling performance, offering a promising strategy for automotive projection systems.