US Patent 9036158 Pattern projector

A pattern projector, comprising a light source, configured to emit a beam of light. A transparent substrate, which has a pair of mutually-opposed planar surfaces is configured to receive and propagate the beam within the substrate by total internal reflection between the planar surfaces. The transparent substrate comprises a diffractive structure that is formed on one of the planar surfaces and is configured to direct at least a part of the beam to propagate out of the substrate in a direction that is angled away from the surface and to create a pattern comprising multiple interleaved light and dark areas.