Wide angle mini-LEDs combined with multifocal micro reflector cavity for thin portable device flashlight

Abstract

LEDs employed in portable device flashes are Lambertian light sources, additional optical components such as Fresnel lenses and reflector cups must be incorporated to adjust the light distribution. This results in a need for a certain module thickness or high alignment precision. This paper introduces a modification in the packaging structure of mini-LEDs by employing a first optical design to create wide-angle mini-LEDs (WA mini-LEDs) with a light emission angle of 180°. A multi-focal micro-reflector cavity (MF-MRC) is included in the packaging process, thus enabling the achievement of a slim flash module. For the prototype design, measurements were conducted using WA mini-LEDs combined with a 2 mm height MF-MRC. The full width at half maximum can be reduced to 56° while maintaining a uniformity of up to 60% across all measurement points. Additionally, the center illuminance is 3.24 times higher compared to Lambertian mini-LED light sources.