Method and system for dual projector waveguide displays with wide field of view using a combined pupil expander-extractor (CPE)
An eyepiece waveguide for an augmented reality display system includes a substrate having a first surface and a second surface and a diffractive input coupling element formed on or in the first surface or the second surface of the substrate. The diffractive input coupling element is configured to receive an input beam of light and to couple the input beam into the substrate as a guided beam. The eyepiece waveguide also includes a diffractive combined pupil expander-extractor (CPE) element formed on or in the first surface or the second surface of the substrate. The diffractive CPE element includes a first portion and a second portion divided by an axis. A first set of diffractive optical elements is disposed in the first portion and oriented at a positive angle with respect to the axis and a second set of diffractive optical elements is disposed in the second portion and oriented at a negative angle with respect to the axis.
1. An eyepiece waveguide for an augmented reality display system, the eyepiece waveguide comprising:
a substrate having a first surface and a second surface;
a diffractive input coupling element formed on or in the first surface or the second surface of the substrate, the diffractive input coupling element being configured to receive an input beam of light and to couple the input beam of light into the substrate as a guided beam; and
a diffractive combined pupil expander-extractor (CPE) element formed on or in the first surface or the second surface of the substrate, wherein the diffractive CPE element includes a first portion and a second portion divided by an axis, wherein:
a first set of diffractive optical elements disposed in the first portion and oriented at a positive angle with respect to the axis; and
a second set of diffractive optical elements disposed in the second portion and oriented at a negative angle with respect to the axis.
2. The eyepiece waveguide of claim 1 wherein the positive angle is ˜30° and the negative angle is ˜−30°.
3. The eyepiece waveguide of claim 1 wherein the first set of diffractive optical elements comprises a first set of gratings and the second set of diffractive optical elements comprises a second set of diffraction gratings.
4. The eyepiece waveguide of claim 1 wherein the first set of diffractive optical elements extends into the second portion and the second set of diffractive optical elements extends into the first portion to form an overlap region.
5. The eyepiece waveguide of claim 4 wherein the overlap region is centered on the axis.
6. The eyepiece waveguide of claim 5 wherein the axis passes through the diffractive input coupling element.
7. The eyepiece waveguide of claim 1 wherein the input beam of light impinges on the diffractive input coupling element at a non-zero angle of incidence.
8. The eyepiece waveguide of claim 7 wherein the diffractive input coupling element is characterized by a grating period such that a cone of rays incoupled by the diffractive input coupling element is centered on an axis parallel to the substrate.
9. An eyepiece waveguide for an augmented reality display system, the eyepiece waveguide comprising:
a substrate having a first surface and a second surface;
a first diffractive input coupling element formed on or in the first surface or the second surface of the substrate, the first diffractive input coupling element being configured to receive a first input beam of light and to couple the first input beam of light into the substrate as a first guided beam;
a second diffractive input coupling element formed on or in the first surface or the second surface of the substrate, the second diffractive input coupling element being configured to receive a second input beam of light and to couple the second input beam of light into the substrate as a second guided beam;
a diffractive combined pupil expander-extractor (CPE) element formed on or in the first surface or the second surface of the substrate, the diffractive CPE element being positioned to:
receive the first guided beam from the first diffractive input coupling element;
receive the second guided beam from the second diffractive input coupling element;
outcouple at least a portion of the first guided beam over a first range of angles to form a first field of view of a combined field of view; and
outcouple at least a portion of the second guided beam over a second range of angles to form a second field of view of the combined field of view.
10. The eyepiece waveguide of claim 9 wherein the diffractive CPE element comprises a first set of gratings disposed in a first portion of a first region oriented at ˜30° to an axis and a second set of gratings disposed in a second portion of the first region oriented at ˜−30° to the axis.
11. The eyepiece waveguide of claim 10 wherein the diffractive CPE element comprises a third set of gratings disposed in a first portion of a second region oriented at ˜150° to the axis and a fourth set of gratings disposed in a second portion of the second region oriented at ˜−150° to the axis.
12. The eyepiece waveguide of claim 9 wherein the first input beam of light is incident on the substrate at a non-normal angle of incidence and the first field of view of the combined field of view is centered at the non-normal angle of incidence.
13. The eyepiece waveguide of claim 12 wherein the second input beam of light is incident on the substrate at zero minus the non-normal angle of incidence and the second field of view of the combined field of view is centered at zero minus the non-normal angle of incidence.
14. The eyepiece waveguide of claim 9 wherein the first field of view and the second field of view are tiled.
15. The eyepiece waveguide of claim 14 wherein a portion of the first field of view overlaps with a portion of the second field of view.
16. A waveguide display disposed in glasses, the waveguide display comprising:
a first projector;
a second projector;
a first incoupling grating (ICG) optically coupled to the first projector;
a second ICG optically coupled to the second projector, wherein an axis passes through the first ICG and the second ICG;
a first diffractive region optically coupled to the first ICG and including:
a first portion comprising a first set of gratings oriented at a positive angle with respect to the axis; and
a second portion comprising a second set of gratings oriented at a negative angle with respect to the axis; and
a second diffractive region optically coupled to the second ICG and including:
a first portion comprising a third set of gratings oriented at 180° minus the positive angle with respect to the axis; and
a second portion comprising a fourth set of gratings oriented at −180° minus the negative angle with respect to the axis.
17. The waveguide display of claim 16 wherein the first diffractive region and the second diffractive region overlap to form an overlap region.
18. The waveguide display of claim 17 wherein the overlap region is disposed at a midpoint between the first ICG and the second ICG.
19. The waveguide display of claim 16 wherein first display light from the first projector impinges on the first ICG at a non-zero angle of incidence.
20. The waveguide display of claim 19 wherein the first ICG is characterized by a grating period such that a cone of rays incoupled by the first ICG is centered on the axis passing through the first ICG and the second ICG.