Waveguide-based displays with exit pupil expander

Patent metadata

Field	Value
Publication number	US-10025093-B2
Application number	US-201615097646-A
Country	US
Kind code	B2
Filing date	Apr 13, 2016
Priority date	Apr 13, 2016
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A near eye or heads up display system includes a scan beam projector engine, an optical waveguide, and an exit pupil expander (EPE) optically coupled between the scan beam projector engine and the optical waveguide. The EPE improves the optical performance of the display system. The EPE could include a diffusive optical element, diffractive optical element, micro-lens array (MLA), or relay of aspherical lenses. A dual MLA EPE may have cells that prevent cross-talk between adjacent pixels. A dual MLA EPE may have a non-periodic lens array. The optical power of one MLA may be different from the other MLA.

First claim

What is claimed is:

1. An apparatus, comprising:
a scan beam projector configured to project a light beam;
an optical waveguide including a bulk-substrate, an input-coupler, an output-coupler, and a diffractive optical element between the input-coupler and the output-coupler; and
an exit pupil expander optically coupled between the scan beam projector and the optical waveguide, the exit pupil expander configured to couple the light beam from the scan beam projector into the input-coupler,
the exit pupil expander comprising a dual microlens array configured to expand an exit pupil associated with the scan beam projector,
wherein the dual microlens array comprises a first microlens array that is configured to receive the light beam in first lenses in a first plane and a second microlens array that is configured to output the light beam in second lenses in a second plane parallel to the first plane, wherein the first lenses are periodic and the second lenses are non-periodic.

2. The apparatus of claim 1 , wherein the diffractive optical element further comprises a first diffractive optical element and a second diffractive optical element, wherein the input-coupler comprises the first diffractive optical element configured to diffract the light beam to the second diffractive optical element, wherein the second diffractive optical element is configured to diffract the light beam to the output-coupler, wherein at least one of the first diffractive optical element or the second diffractive optical element is configured to expand the light beam in at least one direction.

3. The apparatus of claim 1 , further comprising an opacity filter aligned with the optical waveguide, the opacity filter is configured to selectively block natural light from passing through the optical waveguide.

4. The apparatus of claim 1 , wherein the first microlens array comprises first lenses and the second microlens array comprises second lenses that do not match the first lenses.

5. A method comprising:
scanning a light beam using a scan beam projector;
expanding an exit pupil of the light beam from the scan beam projector using an exit pupil expander, comprising channeling portions of the light beam that correspond to virtual pixels in the light beam through different physical sections of the exit pupil expander while preventing cross talk between adjacent virtual pixels;
optically coupling the light beam from the exit pupil expander into an input-coupler of an optical waveguide;
diffracting the light beam from the input-coupler to an intermediate diffractive element in the optical waveguide;
diffracting the light beam from the intermediate diffractive element to an output-coupler in the optical waveguide; and
diffracting the light beam from the output-coupler to outside of the optical waveguide.

6. The method of claim 5 , wherein the exit pupil expander comprises a microlens array, wherein expanding the exit pupil of the light beam from the scan beam projector using the exit pupil expander comprises:
refracting the light beam from lenses in the microlens array at different angles depending on a spatial location of the lenses in the microlens array.

7. The method of claim 5 , wherein expanding the exit pupil of the light beam from the scan beam projector using the exit pupil expander comprises:
applying a first optical power to the light beam at an input of the exit pupil expander; and
applying a second optical power to the light beam at an output of the exit pupil expander, the second optical power is not equal to the first optical power.

8. A see-through, near eye display system, comprising:
a light engine comprising a laser, a scanning mirror, and logic configured to scan a light beam from the laser with the scanning mirror;
a pupil replicator including a bulk-substrate, an input-coupler, an output-coupler, and a diffractive optical element between the input-coupler and the output-coupler, the output-coupler configured to deliver the light beam to an eye of a wearer of the see-through, near eye display system; and
an exit pupil expander optically coupled between the light engine and the pupil replicator, the exit pupil expander configured to couple the light beam from the light engine into the input-coupler,
the exit pupil expander comprising a dual microlens array having a first microlens array configured to receive the light beam in first lenses in a first plane and a second microlens array configured to output the light beam in second lenses in a second plane parallel to the first plane, wherein ones of the second lenses have a different numerical aperture from ones of the first lenses.

9. The see-through, near eye display system of claim 8 , wherein the dual microlens array is configured to provide a spatially dependent refraction angle.

10. The see-through, near eye display system of claim 8 , wherein the dual microlens array comprises a body having a first side and a second side, the body comprising cells configured to channel light from ones of the first lenses to corresponding ones of the second lenses, the cells configured to prevent cross-talk between adjacent cells.

11. An apparatus, comprising:
a scan beam projector configured to project a light beam;
an optical waveguide including a bulk-substrate, an input-coupler, an output-coupler, and a diffractive optical element between the input-coupler and the output-coupler; and
an exit pupil expander optically coupled between the scan beam projector and the optical waveguide, the exit pupil expander configured to couple the light beam from the scan beam projector into the input-coupler,
the exit pupil expander comprising a series of aspherical refractive optical elements configured to expand an exit pupil of the scan beam projector.

12. An apparatus, comprising:
a scan beam projector configured to project a light beam;
an optical waveguide including a bulk-substrate, an input-coupler, an output-coupler, and a diffractive optical element between the input-coupler and the output-coupler;
a series of refractive optical elements comprising a first set of lenses and a second set of lenses, the series of refractive optical elements correcting for chromatic aberration; and
an exit pupil expander optically coupled between the scan beam projector and the optical waveguide, the exit pupil expander optically coupled between the first set and the second set of lenses, the exit pupil expander configured to couple the light beam from the scan beam projector into the input-coupler.

13. A method comprising:
scanning a light beam using a scan beam projector;
expanding an exit pupil of the light beam from the scan beam projector using an exit pupil expander, comprising:
applying a first optical power to the light beam at an input of the exit pupil expander; and
applying a second optical power to the light beam at an output of the exit pupil expander, the second optical power is not equal to the first optical power;

optically coupling the light beam from the exit pupil expander into an input-coupler of an optical waveguide;
diffracting the light beam from the input-coupler to an intermediate diffractive element in the optical waveguide;
diffracting the light beam from the intermediate diffractive element to an output-coupler in the optical waveguide; and
diffracting the light beam from the output-coupler to outside of the optical waveguide.

14. The method of claim 13 , further comprising:
propagating the light beam from the input-coupler through the optical waveguide to an output coupler of the optical waveguide; and
optically coupling the light beam through output coupler to outside

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Wall Richard Andrew
• Vallius Tuomas
• Juhola Mikko

Classifications

• G02B27/0172

  characterised by optical features · CPC title

• G02B26/101

  with both horizontal and vertical deflecting means, e.g. raster or XY scanners (colour television using laser beams scanning a display screen H04N9/3129) · CPC title

• G02B6/0026

  Wavelength selective element, sheet or layer, e.g. filter or grating · CPC title

• G02B27/0081 Primary

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

• G02B3/04

  with continuous faces that are rotationally symmetrical but deviate from a true sphere {, e.g. so called "aspheric" lenses} · CPC title