Optical waveguide using overlapping optical elements
An optical waveguide that performs both in-coupling and out-coupling using two diffractive optical elements is provided. Each optical element is a diffraction grating and can be applied to the same or different surface of the optical waveguide. The diffraction gratings overlap to form two overlapping regions. The first overlapping region in-couples light into the waveguide and the second overlapping region out-couples light from the optical waveguide. Because the optical waveguide only uses two gratings, and therefore only has two grating vectors, the optical waveguide is easier to manufacture than optical waveguides with a greater number of grating vectors.
1. An optical waveguide comprising:
a first surface;
a second surface; and
a first optical element disposed on the first surface or the second surface and defining a first region; and
a second optical element disposed on the first surface or the second surface and defining a second region, wherein the first optical element overlaps the second optical element to define a third region and a fourth region, wherein the third region is configured to:
receive a beam of light; and
in-couple the received beam of light into the optical waveguide;
wherein the first and second regions are configured to cause the received beam of light to traverse within the optical waveguide in a first direction; and
wherein the fourth region is configured to out-couple the received beam of light from the optical waveguide in a second direction.
2. The optical waveguide of claim 1 , wherein the first optical element comprises a diffractive optical element.
3. The optical waveguide of claim 2 , wherein the first optical element comprises a surface relief grating, a polarization grating, a volume grating, or an index modulated grating.
4. The optical waveguide of claim 1 , wherein the beam of light out-couples from the optical waveguide through the first surface.
5. The optical waveguide of claim 1 , wherein the beam of light in-couples into the optical waveguide through the first surface.
6. The optical waveguide of claim 1 , wherein the beam of light out-couples from the optical waveguide through the second surface.
7. The optical waveguide of claim 1 , wherein a grating direction of the first optical element is different than a grating direction of the second optical element.
8. The optical waveguide of claim 1 , wherein the first optical element is disposed on the first surface and the second optical element is disposed on the second surface.
9. A head mounted display device comprising:
a projector;
a controller coupled to the projector and configured to cause the projector to project a beam of light; and
a plurality of optical waveguides, wherein each optical waveguide comprises:
a first surface;
a second surface;
a first optical element disposed on the first surface of the second surface and defining a first region; and
a second optical element disposed on the first surface or the second surface and defining a second region, wherein the first optical element overlaps the second optical element to define a third region and a fourth region, wherein the third region is configured to:
receive a beam of light; and
in-couple the received beam of light into the optical waveguide;
wherein the first and second regions are configured to cause the received beam of light to traverse within the optical waveguide in a first direction; and
wherein the fourth region is configured to out-couple the received beam of light from the optical waveguide in a second direction.
10. The head mounted display of claim 9 , wherein the first optical element comprises a diffractive optical element.
11. The head mounted display of claim 10 , wherein the first optical element comprises a surface relieve grating.
12. The head mounted display of claim 9 , wherein the beam of light in-couples into the optical waveguide through the first surface.
13. The head mounted display of claim 9 , wherein the beam of light out-couples from the optical waveguide through the second surface.
14. The head mounted display of claim 9 , wherein a grating direction of the first optical element is different than a grating direction of the second optical element.
15. The head mounted display of claim 9 , wherein the beam of light out-couples from the optical waveguide through the first surface.
16. A method comprising:
providing a first optical element on a first surface of an optical waveguide, wherein the first optical element defines a first region;
providing a second optical element on a second surface of the optical waveguide, wherein the second optical element defines a second region, and wherein the first optical element overlaps the second optical element to define a third region and a fourth region;
receiving a beam of light by the third region;
in-coupling the received beam of light into the optical waveguide by the third region;
causing the received beam of light to traverse within the optical waveguide in a first direction by one or both of the first region and the second region; and
out-coupling the received beam of light from the optical waveguide in a second direction by the fourth region.
17. The method of claim 16 , wherein the first optical element comprises a diffractive optical element.
18. The method of claim 16 , wherein a grating direction of the first optical element is different than a grating direction of the second optical element.
19. The method of claim 16 , wherein the first surface comprises a front surface of the optical waveguide and the second surface comprises a rear surface of the optical waveguide.
20. The method of claim 16 , wherein the first optical element comprises a surface relief grating, a polarization grating, a volume grating, or an index modulated grating.