Apple Inc.
Direct optical coupling of scanning light engines to a waveguide

Abstract:

An optical apparatus includes an optically transparent slab waveguide including first and second, mutually-parallel planar faces and an edge non-parallel to the planar faces. A radiation source directs a beam of optical radiation to enter the waveguide through the first planar face at an entrance location and entrance angle selected so that the beam subsequently exits the waveguide at an exit location in a surface selected from among the second planar face and the edge. A scanning mirror is positioned to receive the beam that has exited through the surface and to reflect the beam back through the surface into the waveguide while the scanning mirror rotates about an axis parallel to the surface over a range of angles selected so as to cause the beam, after reflection back into the waveguide through the surface, to propagate within the waveguide by total internal reflection (TIR).