Patent ID: 11947314
Assignee: A9.COM, INC.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 6:
7. A waveguide image combiner for combining light from real imagery with light from a light engine, said waveguide image combiner comprising:
a. an optically transparent substrate having top and bottom surfaces; and
b. a pair of incoupling and outcoupling volume holographic optical elements (VHOEs) spaced apart and overlaid on the top surface of the optically transparent substrate;
wherein the optically transparent substrate is configured to convey light from the incoupling VHOE to the outcoupling VHOE via total internal reflection (TIR),
wherein the incoupling VHOE comprises a first Bragg grating and a second Bragg grating with substantially identical diffraction geometries and Bragg conditions shifted with respect to each other,
wherein the first Bragg grating is configured to diffract, at a first diffraction angle, a light beam that is incident to the incoupling VHOE at an incident angle,
wherein the second Bragg grating is configured to diffract, at a second diffraction angle, the light beam that is incident at the incident angle, and
wherein the second diffraction angle is substantially the same as the first diffraction angle.