Display illumination light guide

Abstract

A near-eye display device has a multi-color light source, a micro display, an optical system and a light guide. The optical system collimates and redirects light from the micro display to an optical axis of the device. The light guide comprises multiple color-specific layers, an in-coupling diffraction grating through which light from the source enters the light guide, and an out-coupling diffraction grating through which light from the light guide exits towards the micro display. Two distinct embodiments are detailed: each different color-specific layer of the light guide is defined by a different refractive index; or by a different color-specific filter. In one example there is one in-coupling diffraction grating through which all light from the source enters the light guide; in another there are at least first and second in-coupling diffraction gratings on opposed light guide surfaces through which different colors enter the light guide.

Dependencies are inferred from the claim text.