Optical assemblies having polarization volume gratings for projecting augmented reality content

Patent metadata

Field	Value
Publication number	US-11048087-B2
Application number	US-201916436729-A
Country	US
Kind code	B2
Filing date	Jun 10, 2019
Priority date	Jun 10, 2019
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

An optical assembly for projecting light from a display includes a first optical waveguide, a reflective optical element configured, and a first in-coupler. The reflective optical element is configured to receive first light having first polarization from the display and to reflect the first light as second light having second polarization distinct from the first polarization. The first in-coupler is coupled with the first optical waveguide. The first in-coupler is configured to receive and transmit the first light. The first in-coupler is further configured to receive the second light and redirect a first portion of the second light so that the first portion of the second light undergoes total internal reflection inside the first optical waveguide.

First claim

What is claimed is:

1. An optical assembly for projecting light from a display, comprising:
a first optical waveguide;
a reflective optical element positioned to receive first light having first circular polarization and to reflect the first light as second light having second circular polarization distinct from the first circular polarization;
a first in-coupler coupled with the first optical waveguide, the first in-coupler positioned to:
receive from the display, and transmit toward the reflective optical element, the first light having the first circular polarization; and
receive from the reflective optical element the second light having the second circular polarization and redirect a first portion of the second light so that the first portion of the second light undergoes total internal reflection inside the first optical waveguide,

wherein the reflective optical element consists of a negative meniscus lens having a convex lens surface and a concave lens surface, the convex lens surface of the negative meniscus lens coupled with a reflective surface, and the reflective optical element is positioned to focus the first light as the first light is reflected such that the second light is more collimated than the first light.

2. The optical assembly of claim 1 , wherein the first in-coupler is disposed between the display and the reflective optical element and is positioned to transmit the first light toward the reflective optical element while remaining polarization of the first light.

3. The optical assembly of claim 1 , wherein the first in-coupler is selected from the group consisting of: a liquid crystal based polarization selective element, a polarization selective element including a metasurface, a polarization selective element including a resonant structured surface, a polarization selective element including a continuous chiral layer, and a polarization selective element including a birefringent material.

4. The optical assembly of claim 3 , wherein the liquid crystal based polarization selective element is a polarization volume grating.

5. The optical assembly of claim 3 , wherein the first in-coupler is a transmission grating positioned to redirect the first portion of the second light such that the first portion of the second light enters the first optical waveguide at an incident angle that is greater than a critical angle associated with the first optical waveguide.

6. The optical assembly of claim 3 , wherein the first in-coupler is a reflective grating positioned to redirect the first portion of the second light after the second light enters the first optical waveguide, causing the first portion of the second light to impinge on an internal surface of the first optical waveguide at an incident angle that is greater than a critical angle of incidence.

7. The optical assembly of claim 1 , wherein the first in-coupler and a portion of the first optical waveguide are positioned between the display and the reflective optical element.

8. The optical assembly of claim 1 , wherein:
the first in-coupler is positioned to transmit a second portion of the second light, and
the first portion of the second light has a first wavelength range and the second portion of the second light has a second wavelength range distinct from the first wavelength range.

9. The optical assembly of claim 8 , further including:
a second optical waveguide; and
a second in-coupler coupled with the second optical waveguide, the second in-coupler positioned to:
receive from the display, and transmit toward the reflective optical element, the first light having the first circular polarization; and
receive the second portion of the second light and redirect the second portion of the second light so that the second portion of the second light undergoes total internal reflection inside the second optical waveguide.

10. The optical assembly of claim 1 , further including one or more lenses between the display and the first optical waveguide, the one or more lenses including a first lens positioned to focus the first light.

11. A method of projecting light from an electronic display, the method comprising:
transmitting first light having first circular polarization from the electronic display through one or more optical components, the one or more optical components including a first in-coupler and a first optical waveguide;
receiving, by a reflective optical element, the first light having the first circular polarization transmitted through the one or more optical components;
reflecting, by the reflective optical element, the first light having the first circular polarization as second light having second circular polarization distinct from the first circular polarization;
receiving, by the first in-coupler, the second light having the second circular polarization;
redirecting, by the first in-coupler, a first portion of the second light having the first second circular polarization so that the first portion of the second light undergoes total internal reflection inside the first optical waveguide; and
focusing, by the reflective optical element, the first light as the first light is reflected such that the second light is more collimated than the first light, wherein the reflective optical element consists of a negative meniscus lens having a convex lens surface and a concave lens surface and the convex lens surface of the negative meniscus lens is coupled with a reflective surface.

12. The method of claim 11 , wherein the first in-coupler is selected from the group consisting of: a liquid crystal based polarization selective element, a polarization selective element including a metasurface, a polarization selective element including a resonant structured surface, a polarization selective element including a continuous chiral layer, and a polarization selective element including a birefringent material.

13. The method of claim 12 , wherein the liquid crystal based polarization selective element is a polarization volume grating.

14. The method of claim 11 , wherein the first in-coupler and a section of the first optical waveguide are positioned between the electronic display and the reflective optical element.

15. The method of claim 11 , further comprising:
transmitting, by the first in-coupler, a second portion of the second light, wherein the first portion of the second light has a first wavelength range and the second portion of the second light has a second wavelength range distinct from the first wavelength range.

16. The method of claim 15 , wherein the one or more optical components further include a second optical waveguide and a second in-coupler coupled with the second optical waveguide, the method further comprising:
receiving, with the second in-coupler, the second portion of the second light; and
redirecting, with the second in-coupler, the second portion of the second light so that the second portion of the second light undergoes total internal reflection inside the second optical waveguide.

17. A display device, comprising:
a display configured to output first light having first circular polarization;
a first optical waveguide;
a reflective optical element positioned to receive the first light having the first circular polarization from the display and to reflect the first light as second light having second circular polarization distinct from the first circular polarization; and
a first in-coupler coupled with the first optical waveguide, the first in-coupler positioned to:
receive from the display, and transmit toward the reflective optical element, the firs

Assignees

• Facebook Tech Llc

Inventors

• Wheelwright Brian
• Lee Yun-Han
• Amirsolaimani Babak
• Gao Weichuan

Classifications

• G02B2027/015

  involving arrangement aiming to get less bulky devices · CPC title

• G02B2027/0125

  Field-of-view increase by wavefront division · CPC title

• G02B2027/0114

  comprising dichroic elements · CPC title

• G02B27/286

  for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another (G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34) · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title