OPTICAL WAVEGUIDE USING OVERLAPPING OPTICAL ELEMENTS

• US 20190121023A1
• Filed: 12/17/2018
• Published: 04/25/2019
• Est. Priority Date: 05/31/2017
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: TERVO, Jani Kari Tapio
• Granted Patent: US 10,670,805 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/0178 Eyeglass type eyeglass details G02C
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 6/0026 Wavelength selective element, sheet or layer, e.g. filter or grating
• CPC Class Codes: G02B 6/124 Geodesic lenses or integrated gratings
• CPC Class Codes: G02B 6/29323 Coupling to or out of the diffractive element through the lateral surface of the light guide evanescent grating couplers G02B6/29332
• CPC Class Codes: G02B 6/29334 Grating-assisted evanescent light guide couplers, i.e. comprising grating at or functionally associated with the coupling region between the light guides, e.g. with a grating positioned where light fields overlap in the coupler
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence
• CPC Class Codes: G02B 6/43 Arrangements comprising a plurality of opto-electronic elements and associated optical interconnections

Abstract

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.

Claims

1. An optical waveguide comprising:

a first optical element disposed on a first surface or a second surface of the optical waveguide; and

a second optical element disposed on the first surface or the second surface of the optical waveguide,

wherein a section of the first optical element is configured to in-couple a received beam of light into the optical waveguide; and

wherein a section of the second optical element 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 optical element disposed on a first surface or a second surface of the optical waveguide and defining a first region; and

a second optical element disposed on the first surface or the second surface of the optical waveguide and defining a second region;

wherein a section of the first optical element is configured to in-couple a 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 a section of the second optical element is configured to out-couple the received beam of light from the optical waveguide in a second direction (Y-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;

receiving a beam of light and in-coupling the received beam of light into the optical waveguide by a section of the first optical element of the optical waveguide;

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 a section of the second optical element.

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.