US Patent 10345506 Light projecting method and device

A waveguide comprises a first surface and a second surface. At least one of the first surface or the second surface comprises a plurality of grating structures. The waveguide is configured to guide an in-coupled light beam to undergo total internal reflection between the first surface and the second surface. The grating structures are configured to disrupt the total internal reflection to cause at least a portion of the in-coupled light beam to couple out of the waveguide from the first surface, the portion of the in-coupled light beam coupled out of the waveguide forming out-coupled light beams.