Optical efficiency of reflective waveguides for microLEDs

High efficiency of near-eye-display optics is achieved by maximizing light coupling between its’ three main components: the image generator, the collimating optics, and the waveguide itself. Image generator based on microLED have relatively large area and high beam divergence, thereby generating light beams characterized by high Etendue value. Inherent properties of reflective waveguides enable efficient coupling of these beams despite their high divergence (Etendue). This talk will review these properties, while reviewing the waveguides architecture and method of production. For comparison, the talk will also include ‘back-of-envelope’ efficiency calculation assuming various image generators (micro-LED or LCOS) when implemented onto the various waveguides (reflective or diffractive). In doing so, we will consider standard optical parameters such as aperture size, F-number or dispersion, and their individual impact on total system efficiency.