Volume bragg gratings for near-eye waveguide display

Patent metadata

Field	Value
Publication number	US-11067811-B2
Application number	US-201916726667-A
Country	US
Kind code	B2
Filing date	Dec 24, 2019
Priority date	Jan 11, 2019
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

A waveguide display includes a substrate transparent to visible light, a coupler configured to couple display light into the substrate such that the display light propagates within the substrate through total internal reflection, a first multiplexed volume Bragg grating (VBG) on the substrate, and a second multiplexed VBG on the substrate. The second multiplexed VBG overlaps with the first multiplexed VBG in at least a see-through region of the waveguide display. The first multiplexed VBG is configured to diffract the display light to two or more regions of the second multiplexed VBG, and the second multiplexed VBG is configured to diffract the display light to two or more regions of an eyebox of the waveguide display.

First claim

What is claimed is:

1. A waveguide display, comprising:
a substrate transparent to visible light;
a coupler configured to couple display light into the substrate such that the display light propagates within the substrate through total internal reflection;
a first multiplexed volume Bragg grating (VBG) on a first region of the substrate; and
a second multiplexed VBG only on a second region of the substrate, the second region different from the first region, and the second multiplexed VBG overlapping with the first multiplexed VBG in at least a see-through region of the waveguide display,
wherein the first multiplexed VBG is configured to diffract the display light to two or more regions of the second multiplexed VBG along a first direction, and
wherein the second multiplexed VBG is configured to diffract the display light to two or more regions of an eyebox of the waveguide display along a second direction.

2. The waveguide display of claim 1 , wherein the first multiplexed VBG includes fewer than 100 VBGs recorded by fewer than 100 exposures.

3. The waveguide display of claim 2 , wherein the first multiplexed VBG includes fewer than 50 VBGs recorded by fewer than 50 exposures.

4. The waveguide display of claim 1 , wherein the first multiplexed VBG is characterized by a thickness less than 100 μm.

5. The waveguide display of claim 4 , wherein the thickness of the first multiplexed VBG is less than 50 μm.

6. The waveguide display of claim 1 , wherein the second multiplexed VBG includes fewer than 100 VBGs recorded by fewer than 100 exposures.

7. The waveguide display of claim 6 , wherein the second multiplexed VBG includes fewer than 50 VBGs recorded by fewer than 50 exposures.

8. The waveguide display of claim 1 , further comprising a third multiplexed VBG on the substrate, the third multiplexed VBG configured to diffract the display light coupled into the substrate by the coupler to the first multiplexed VBG.

9. The waveguide display of claim 8 , wherein the third multiplexed VBG includes a plurality of VBGs, each VBG of the plurality of VBGs having a respective grating vector same as a grating vector of a respective VBG in the first multiplexed VBG.

10. The waveguide display of claim 9 , wherein the first multiplexed VBG and the third multiplexed VBG are recorded by a same number of exposures.

11. The waveguide display of claim 1 , further comprising:
a third multiplexed VBG on the substrate; and
a fourth multiplexed VBG on the substrate,
wherein the third multiplexed VBG is configured to diffract a first portion of the display light coupled into the substrate by the coupler to the first multiplexed VBG; and
wherein the fourth multiplexed VBG is configured to diffract a second portion of the display light coupled into the substrate by the coupler to the first multiplexed VBG.

12. The waveguide display of claim 11 , wherein the first portion of the display light and the second portion of the display light correspond to different wavelength ranges or different fields of view.

13. The waveguide display of claim 11 , wherein:
the first multiplexed VBG includes a first set of VBGs and a second set of VBGs;
the third multiplexed VBG includes a third set of VBGs, each VBG in the third set of VBGs having a respective grating vector same as a grating vector of a respective VBG in the first set of VBGs; and
the fourth multiplexed VBG includes a fourth set of VBGs, each VBG in the fourth set of VBGs having a respective grating vector same as a grating vector of a respective VBG in the second set of VBGs.

14. The waveguide display of claim 13 , wherein the first set of VBGs and the second set of VBGs are in different regions of the first multiplexed VBG.

15. The waveguide display of claim 11 , wherein the third multiplexed VBG and the fourth multiplexed VBG are in different regions on a surface of the substrate or are on different layers or surfaces of the substrate.

16. The waveguide display of claim 1 , wherein:
the first multiplexed VBG includes a first region and a second region;
the first region is configured to diffract the display light coupled into the substrate by the coupler to the second region of the first multiplexed VBG; and
the second region of the first multiplexed VBG at least partially overlaps with the second multiplexed VBG and is configured to diffract the display light to the second multiplexed VBG.

17. The waveguide display of claim 1 , wherein the coupler includes a diffractive coupler, a refractive coupler, or a reflective coupler.

18. The waveguide display of claim 1 , wherein:
the first multiplexed VBG is configured to expand the display light in the first direction; and
the second multiplexed VBG is configured to expand the display light in the second direction.

19. A method of displaying images using a waveguide display, the method comprising:
coupling, by a coupler, display light into a substrate that is transparent to visible light;
guiding, by the substrate, the display light to propagate within the substrate;
diffracting, by two or more regions of a first multiplexed volume Bragg grating (VBG) on a first region of the substrate, the display light to two or more regions of a second multiplexed VBG along a first direction, the second multiplexed VBG only on a second region of the substrate, and the second region different from the first region; and
diffracting, by each of the two or more regions of the second multiplexed VBG, the display light from the first multiplexed VBG to two or more regions of an eyebox of the waveguide display along a second direction,
wherein the second multiplexed VBG overlaps with the first multiplexed VBG in at least a see-through region of the waveguide display.

20. The method of claim 19 , further comprising:
diffracting, by a third multiplexed VBG, the display light coupled into the substrate by the coupler to the first multiplexed VBG.

21. The method of claim 20 , wherein each VBG in the third multiplexed VBG has a respective grating vector same as a grating vector of a respective VBG in the first multiplexed VBG.

22. The method of claim 19 , further comprising:
diffracting, by a third multiplexed VBG, display light in a first wavelength range to the first multiplexed VBG; and
diffracting, by a fourth multiplexed VBG, display light in a second wavelength range to the first multiplexed VBG,
wherein the fourth multiplexed VBG is closer to the second multiplexed VBG than the third multiplexed VBG.

23. The method of claim 22 , wherein:
diffracting the display light in the first wavelength range to the first multiplexed VBG includes diffracting the display light in the first wavelength range to a first region of the first multiplexed VBG; and
diffracting the display light in the second wavelength range to the first multiplexed VBG includes diffracting the display light in the second wavelength range to a second region of the first multiplexed VBG that is offset from the first region.

Assignees

• Facebook Tech Llc

Inventors

• Chi Wanli
• Lee Hee Yoon
• Saarikko Pasi

Classifications

• G02B5/32

  Holograms used as optical elements · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title

• G02B27/0081

  with means for altering, e.g. enlarging, the entrance or exit pupil · CPC title

• G02F1/011 Primary

  in optical waveguides, not otherwise provided for in this subclass · CPC title

• G09G3/002

  to project the image of a two-dimensional display, such as an array of light emitting or modulating elements or a CRT · CPC title