Waveguide display with a small form factor, a large field of view, and a large eyebox

• US 10,585,287 B2
• Filed: 12/07/2018
• Issued: 03/10/2020
• Est. Priority Date: 12/20/2016
• Status: Active Grant

• Current Assignee: META Platforms Technologies LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Original Assignee: Facebook Technologies, LLC (Meta Platforms, Inc. (f/k/a Facebook, Inc.))
• Inventors: Lee, Hee Yoon, Chi, Wanli, Saarikko, Pasi
• Primary Examiner(s): Wong, Tina M
• Application Number:
  US16/213,839
• Publication Number:
  US 20190107723A1
• Time in Patent Office: 459 Days
• Field of Search: None
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 2027/015 involving arrangement aiming to get less bulky devices
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0035 provided on the surface of the light guide or in the bulk of it

Abstract

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.

Claims

1. A waveguide system comprising:

a coupling element for in-coupling light into a waveguide, the coupling element changing a direction of a wavevector by a first amount;

a first one-dimensional decoupling grating configured to receive light from the waveguide and to change the direction of the wavevector by a second amount by diffracting at least a first portion of the in-coupled light;

a second one-dimensional decoupling grating configured to change the direction of the wavevector 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, the second one-dimensional decoupling grating facing opposite the first one-dimensional decoupling grating, a sum of the first amount, second amount, and third amount being substantially zero and predetermined based on a location of the eyebox,

wherein the first one-dimensional decoupling grating and the second one-dimensional decoupling grating overlap along a direction parallel to a surface of the waveguide.

2. The waveguide system of claim 1, wherein the first one-dimensional decoupling grating is a diffraction grating and wherein the first portion of the in-coupled light is based on an incident location of the in-coupled light.

3. The waveguide system of claim 2, wherein the first one-dimensional decoupling grating is 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.

4. The waveguide system of claim 1, wherein the second one-dimensional decoupling grating is a diffraction grating and wherein the second portion of the in-coupled light is based on a location of an incident location of the in-coupled light.

5. The waveguide system of claim 4, wherein the second one-dimensional decoupling grating is configured to adjust the second portion of the in-coupled light based on an output angle of inclination of the diffracted second portion of the in-coupled light.

6. The waveguide system of claim 1, wherein a pitch of at least one of the coupling element, the first one-dimensional decoupling grating, and the second one-dimensional decoupling grating is in a range of 300-600 nm.

7. The waveguide system of claim 1, wherein the waveguide is configured to expand the in-coupled light in at least one dimension.

8. The waveguide system of claim 7, wherein each of the first one-dimensional decoupling grating and the second one-dimensional decoupling grating is configured to expand the in-coupled image light along a different dimension and to out-couple the light along a third dimension.

9. The waveguide 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.

10. The waveguide system of claim 1, wherein the coupling element and the first one-dimensional decoupling grating are separated by a distance at least along a first dimension and a second dimension orthogonal to the first dimension along the surface of the waveguide, and the first coupling element and the second one-dimensional decoupling grating located at a central position along the second dimension.

11. The waveguide system of claim 1, wherein the coupling element is a diffraction grating on at least a first surface and a second surface of the waveguide, the coupling element configured to couple a first angular range and a second angular range of the light, and the second surface is opposite to the first surface.

12. The waveguide system of claim 11, wherein the first portion of light and the second portion of light are in the first angular range, the first one-dimensional decoupling grating expands the first portion of light to the second dimension, and the second one-dimensional decoupling grating expands the second portion of light to the second dimension.

13. The waveguide system of claim 1, wherein the first one-dimensional decoupling grating and the second one-dimensional decoupling grating are located on the surface of the waveguide with an interfacial layer between the first one-dimensional decoupling grating and the second one-dimensional decoupling grating.

14. The waveguide system of claim 1, wherein the first one-dimensional decoupling grating and the second one-dimensional decoupling grating are embedded into the waveguide and separated by an interfacial layer.

15. The waveguide system of claim 1, wherein the coupling element includes a first grating element and a second grating element separated along a first dimension parallel to the surface of the waveguide.

16. The waveguide system of claim 15, wherein the second one-dimensional decoupling grating is located between the first grating element and the second grating element, and the second one-dimensional decoupling grating is located at a central location on a second dimension between the first grating element and the second grating element, the second dimension orthogonal to the first dimension.

17. The waveguide system of claim 1, wherein the coupling element is a refractive surface.

18. The waveguide system of claim 1, wherein the first one-dimensional decoupling grating includes one or more cascaded reflectors configured to deflect the in-coupled light over an angular range, and the second one-dimensional decoupling grating includes one or more cascaded reflectors configured to output the deflected light to the eyebox.

19. The waveguide system of claim 1, wherein the waveguide system provides a diagonal FOV of at least 60 degrees.