WAVEGUIDE DISPLAY WITH A SMALL FORM FACTOR, A LARGE FIELD OF VIEW, AND A LARGE EYEBOX
A waveguide display is used for presenting media to a user. The waveguide display includes light source assembly, an output waveguide, and a controller. The light source assembly includes one or more projectors projecting an image light at least along one dimension. The output waveguide includes a waveguide body with two opposite surfaces. The output waveguide includes a first grating receiving an image light propagating along an input wave vector, a second grating, and a third grating positioned opposite to the second grating and outputting an expanded image light with wave vectors matching the input wave vector. The controller controls the scanning of the one or more source assemblies to form a two-dimensional image.
1 . A system comprising:
a coupling element for in-coupling light into a waveguide;
a first decoupling grating of the waveguide configured to receive the in-coupled light; and
a second decoupling grating of the waveguide opposite the first decoupling grating, the first decoupling grating and the second decoupling grating configured such that the light exiting the waveguide has a wavevector direction matching that of the light in-coupled by the coupling element.
2 . The system of claim 1 , wherein the first decoupling grating and the second decoupling grating are configured to expand the in-coupled light along a different dimension and to out-couple the light along a third dimension.
3 . The system of claim 1 , wherein a pitch of at least one of the coupling element, the first decoupling grating, and the second decoupling grating is in a range of 300-600 nm.
4 . The system of claim 1 , wherein the waveguide is configured to expand the in-coupled light in at least one dimension parallel to the surface of the waveguide.
5 . The system of claim 1 , wherein the first decoupling grating and the second decoupling grating are located on a surface of the waveguide with an interfacial layer between the first decoupling grating and the second decoupling grating.
6 . The system of claim 1 , wherein the first decoupling grating includes one or more cascaded reflectors configured to deflect the in-coupled light over an angular range, and the second decoupling grating includes one or more cascaded reflectors configured to output the deflected light to the eyebox.
7 . The system of claim 1 , wherein the coupling element changes the wavevector direction by a first amount, the first decoupling grating is further configured to change the wavevector direction by a second amount by diffracting at least a first portion of the in-coupled light, and the second decoupling grating is further configured to change the wavevector direction by a third amount by diffracting at least a second portion of the in-coupled light and to output the redirected light to an eyebox.
8 . The system of claim 7 , wherein changing the wavevector direction by the first amount, the second amount, and the third amount result in the light exiting the waveguide having the wavevector direction matching that of the light in-coupled by the coupling element.
9 . The system of claim 7 , wherein the first portion of the in-coupled light is based on an incident location of the in-coupled light.
10 . The system of claim 7 , wherein the first decoupling grating is further configured to adjust the first portion of the in-coupled light based on an output angle of inclination of the diffracted first portion of the in-coupled light.
11 . A system comprising:
a coupling element for in-coupling light into a waveguide;
a first decoupling grating of the waveguide configured to receive the in-coupled light; and
a second decoupling grating of the waveguide opposite the first decoupling grating, the first decoupling grating and the second decoupling grating configured to expand the in-coupled light along a different dimension and to out-couple the light along a third dimension.
12 . The system of claim 11 , wherein the first decoupling grating and the second decoupling grating are configured such that the light exiting the waveguide has a wavevector direction matching that of the light in-coupled by the coupling element.
13 . The system of claim 12 , wherein the coupling element changes the wavevector direction by a first amount, the first decoupling grating is further configured to change the wavevector direction by a second amount by diffracting at least a first portion of the in-coupled light, and the second decoupling grating is further configured to change the wavevector direction by a third amount by diffracting at least a second portion of the in-coupled light and to output the redirected light to an eyebox.
14 . The system of claim 13 , wherein changing the wavevector direction by the first amount, the second amount, and the third amount result in the light exiting the waveguide having the wavevector direction matching that of the light in-coupled by the coupling element.
15 . The system of claim 13 , wherein the first portion of the in-coupled light is based on an incident location of the in-coupled light.
16 . The system of claim 13 , wherein the first decoupling grating is further configured to adjust the first portion of the in-coupled light based on an output angle of inclination of the diffracted first portion of the in-coupled light.
17 . The system of claim 11 , wherein a pitch of at least one of the coupling element, the first decoupling grating, and the second decoupling grating is in a range of 300-600 nm.
18 . The system of claim 11 , wherein the waveguide is configured to expand the in-coupled light in at least one dimension parallel to the surface of the waveguide.
19 . The system of claim 11 , wherein the first decoupling grating and the second decoupling grating are located on a surface of the waveguide with an interfacial layer between the first decoupling grating and the second decoupling grating.
20 . The system of claim 11 , wherein the first decoupling grating includes one or more cascaded reflectors configured to deflect the in-coupled light over an angular range, and the second decoupling grating includes one or more cascaded reflectors configured to output the deflected light to the eyebox.