Diffractive optical elements with analog modulations and switching

Patent metadata

Field	Value
Publication number	US-9885870-B2
Application number	US-201615137185-A
Country	US
Kind code	B2
Filing date	Apr 25, 2016
Priority date	Apr 25, 2016
Publication date	Feb 6, 2018
Grant date	Feb 6, 2018

Abstract

A waveguide configured for use with a near eye display (NED) device can include a light-transmissive substrate configured to propagate light rays through total internal reflection and a switchable diffractive optical element (DOE) on a surface of the substrate that is configured to input and/or output light rays to and/or from the substrate. According to some embodiments, the switchable DOE can include diffractive properties that vary across an area of the DOE. In some embodiments, the switchable DOE includes a surface relief diffraction grating (SRG) a surface of the substrate, a layer of liquid crystal material in contact with the SRG, a layer of conducting material in contact with the liquid crystal material configured to apply the voltage to the liquid crystal material, and a layer of insulating material over the layer of conducting material.

First claim

What is claimed is:

1. An optical waveguide comprising:
a light-transmissive substrate configured for use in a near-eye display (NED) device, the substrate including a plurality of internally reflective surfaces configured to propagate light rays through internal reflection; and
a switchable diffractive optical element (DOE) on a first surface of the plurality of surfaces of the substrate, the switchable DOE configured to input light rays to the substrate or output light rays from the substrate, the switchable DOE having diffractive properties that vary across an area of the switchable DOE;
wherein the switchable DOE includes:
a surface relief diffraction grating (SRG) on the first surface of the substrate; and
a Switchable Bragg Gating (SBG) overlaid on the SRG, the SBG configured to be electronically switchable between a transparent state and a diffractive state.

2. The optical waveguide of claim 1 , wherein the diffractive properties include diffraction efficiency.

3. The optical waveguide of claim 1 , wherein the SRG has a diffraction grating structure that varies in at least one parameter across the area of the DOE.

4. The optical waveguide of claim 3 , wherein the at least one parameter includes one or more of: linewidth, period, depth, modulation direction, slant angle or line shape.

5. The optical waveguide of claim 3 , wherein the variation in the diffractive properties of the switchable DOE is based on the variation in the at least one parameter of the diffraction grating structure of the SRG across the area of the switchable DOE.

6. The optical waveguide of claim 1 , wherein the switchable DOE further includes:
a layer of liquid crystal material in contact with the SRG, the liquid crystal material configured to switch between a transparent state and a diffractive state in response to an applied voltage;
a layer of conducting material in contact with the liquid crystal material configured to apply the voltage to the liquid crystal material; and
a layer of insulating material over the layer of conducting material.

7. The optical waveguide of claim 6 , wherein the SRG is embedded in the layer of liquid crystal material.

8. The optical waveguide of claim 6 , wherein the layer of conducting material comprises indium tin oxide (ITO).

9. The optical waveguide of claim 6 , wherein the layer of insulating material comprises glass.

10. The optical waveguide of claim 1 , wherein the SRG is etched into the substrate.

11. The optical waveguide of claim 1 , wherein the SRG is formed on the substrate.

12. The optical waveguide of claim 1 , wherein the switchable DOE is an in-coupling element configured to input light rays received from an image generator of a near-eye display device into the substrate.

13. The optical waveguide of claim 1 , wherein the switchable DOE is an out-coupling element configured to output light rays from the substrate and to direct the light rays towards an eye of a user of a near-eye display device.

14. The optical waveguide of claim 1 , wherein the substrate comprises glass.

15. The optical waveguide of claim 1 , further comprising a second switchable DOE;
wherein the switchable DOE is configured to input or output light rays collectively representing a first segment of an overall field of view (FOV) of a particular eye of a user of the NED device; and
wherein the second switchable DOE is configured to input or output light rays collectively representing a second segment of the overall FOV of the NED device.

16. A near-eye display device comprising:
a light-emitting microdisplay imager configured to emit light rays collectively representing a generated image; and
a waveguide display including:
a light-transmissive substrate including a plurality of internally reflective surfaces configured to propagate light rays through internal reflection;
an in-coupling element configured to input light rays from the microdisplay imager into the substrate; and
an out-coupling element configured to output propagated light rays from the substrate and to direct the light rays to an eye of a user of the near-eye display device;
wherein both the in-coupling element and out-coupling element include a switchable diffractive optical element (DOE) on at least a portion of a first surface of the plurality of surfaces of the substrate, the switchable DOE configured to switch between a passive transparent state and an active diffractive state, wherein the diffractive properties of the switchable DOE vary across an area of the switchable DOE.

17. A method of manufacturing a waveguide comprising:
forming a diffraction grating on a surface of a light transmissive substrate, the light transmissive substrate configured to propagate light rays through internal reflection, the diffraction grating having one or more physical parameters that vary over an area of the diffraction grating;
filling the diffraction grating with a layer of liquid crystal material; and
overlaying a layer of transparent insulating material with a transparent electrically conductive coating such that the coating is in contact with the liquid crystal material.

18. The method of manufacturing a waveguide of claim 17 , wherein the diffraction grating is formed using a replication process based on a master mold originally manufactured using reactive ion beam etching (RIBE).

19. The method of manufacturing a waveguide of claim 17 , wherein filling the diffraction grating with a layer of liquid crystal material includes spin coating the diffraction grating with liquid crystal material.

20. An optical waveguide comprising:
a light-transmissive substrate configured for use in a near-eye display (NED) device, the substrate including a plurality of internally reflective surfaces configured to propagate light rays through internal reflection; and
a switchable diffractive optical element (DOE) on a first surface of the plurality of surfaces of the substrate, the switchable DOE configured to input light rays to the substrate or output light rays from the substrate, the switchable DOE having diffractive properties that vary across an area of the switchable DOE;
wherein the switchable DOE includes:
a surface relief diffraction grating (SRG) on the first surface of the substrate;
a layer of liquid crystal material in contact with the SRG, the liquid crystal material configured to switch between a transparent state and a diffractive state in response to an applied voltage;
a layer of conducting material in contact with the liquid crystal material configured to apply the voltage to the liquid crystal material; and
a layer of insulating material over the layer of conducting material.

21. An optical waveguide comprising:
a light-transmissive substrate configured for use in a near-eye display (NED) device, the substrate including a plurality of internally reflective surfaces configured to propagate light rays through internal reflection;
a first switchable diffractive optical element (DOE) on a first surface of the plurality of surfaces of the substrate, the first switchable DOE configured to input light rays to the substrate or output light rays from the substrate collectively representing a first segment of an overall field of view (FOV) of a particular eye of a user of the NED device, the first switchable DOE having diffractive properties that vary across an area of the first switchable DOE; and
a second switchable DOE, the second switchable DOE configured to input light rays to the substrate or output light rays fr

Assignees

• Stenberg Petri Antero
• Vallius Tuomas Heikki Sakari
• Microsoft Technology Licensing Llc

Inventors

• Stenberg Petri Antero
• Vallius Tuomas Heikki Sakari

Classifications

• G02F1/011

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

• G02B27/0081

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

• G02B26/0808

  by means of one or more diffracting elements · CPC title

• G02B2027/0123

  comprising devices increasing the field of view · CPC title

• G02B6/00

  Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings · CPC title