Variable-focus virtual image devices based on polarization conversion

Patent metadata

Field	Value
Publication number	US-11036109-B2
Application number	US-201815902927-A
Country	US
Kind code	B2
Filing date	Feb 22, 2018
Priority date	Feb 23, 2017
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

Example display devices include a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide. The waveguide has formed thereon an outcoupling element configured to outcouple a portion of the visible light in a direction normal to the major surface of the waveguide. The example display devices additionally include a polarization-selective notch reflector disposed on a first side of the waveguide and configured to reflect visible light having a first polarization while transmitting the portion of the visible light having a second polarization. The example display devices further include a polarization-independent notch reflector disposed on a second side of the waveguide and configured to reflect visible light having the first polarization and the second polarization, where the polarization-independent notch reflector is configured to convert a polarization of visible light reflecting therefrom.

First claim

What is claimed is:

1. A display device, comprising:
a waveguide configured to propagate visible light under total internal reflection in a direction parallel to a major surface of the waveguide;
an outcoupling element formed on the waveguide and configured to outcouple a portion of the visible light in a direction normal to the major surface of the waveguide;
a polarization-selective notch reflector disposed on a first side of the waveguide and configured to reflect visible light having a first polarization while transmitting visible light having a second polarization; and
a polarization-independent notch reflector disposed on a second side of the waveguide and configured to reflect visible light having the first polarization and visible light having the second polarization, wherein the polarization-independent notch reflector is configured to convert a polarization of visible light reflecting therefrom.

2. The display device of claim 1 , wherein each of the polarization-selective notch reflector and the polarization-independent notch reflector is configured to reflect visible light having a wavelength in a wavelength range corresponding to one of red, green or blue light, while transmitting light having a wavelength outside the wavelength range.

3. The display device of claim 1 , wherein the polarization-selective notch reflector comprises one or more cholesteric liquid crystal (CLC) layers.

4. The display device of claim 3 , wherein each of the one or more CLC layers comprises a plurality of chiral structures,
wherein each of the chiral structures comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction,
wherein the helical pitch is a length in the layer depth direction corresponding to a net rotation angle of the liquid crystal molecules of the chiral structures by one full rotation in the first rotation direction, and
wherein arrangements of the liquid crystal molecules of the chiral structures vary periodically in a lateral direction perpendicular to the layer depth direction.

5. The display device of claim 3 , wherein the first polarization is a first circular polarization and the second polarization is a second circular polarization.

6. The display device of claim 1 , further comprising a first quarter-wave plate and a second quarter-wave plate, wherein the polarization-independent notch reflector is interposed between the first quarter-wave plate and the waveguide, and wherein the polarization-selective notch reflector is interposed between the waveguide and the second quarter-wave plate.

7. The display device of claim 6 , further comprising a first linear polarizing lens and a second linear polarizing lens, wherein the first quarter-wave plate is interposed between the first linear polarizing lens and the polarization-independent notch reflector, and wherein the second quarter-wave plate is interposed between the polarization-selective notch reflector and the second linear polarizing lens.

8. The display device of claim 1 , further comprising a first Pancharatnam-Berry (PB) lens and a second Pancharatnam-Berry (PB) lens disposed on outer sides of the polarization-independent notch reflector and the polarization-selective notch reflector.

9. The display device of claim 1 , further comprising a first quarter-wave plate interposed between the polarization-independent notch reflector and the waveguide.

10. The display device of claim 9 , further comprising a second quarter-wave plate, wherein the polarization-independent notch reflector is interposed between the first quarter-wave plate and the second quarter-wave plate.

11. The display device of claim 10 , further comprising a first linear polarizing lens and a second linear polarizing lens, wherein the first quarter-wave plate is interposed between the first linear polarizing lens and the polarization-independent notch reflector, and wherein the polarization-selective notch reflector is interposed between the waveguide and the second linear polarizing lens.

12. The display device of claim 9 , further comprising a first Pancharatnam-Berry (PB) lens, a second Pancharatnam-Berry (PB) lens disposed on outer sides of the polarization-independent notch reflector and the polarization-selective notch reflector, and a second quarter-wave plate interposed between the second PB lens and the polarization-selective notch reflector.

13. A display device configured to display an image to an eye of a user, the display device comprising:
an optical display comprising a forward side and a rearward side, the rearward side closer to the eye of the user than the forward side, the optical display configured to output light having a wavelength range toward the rearward side;
a first notch reflector disposed rearward of the optical display, the first notch reflector configured to reflect light having the wavelength range output from the optical display; and
a second notch reflector disposed forward of the optical display, the second notch reflector configured to reflect light having the wavelength range,
wherein the first notch reflector is configured to substantially transmit light having a first polarization and substantially reflect light having a second polarization that is different from the first polarization,
wherein the second notch reflector is configured to convert light incident on a rearward face having the second polarization to the first polarization and to redirect the light rearward.

14. The display device of claim 13 , wherein the first notch reflector comprises a cholesteric liquid crystal (CLC) grating (CLCG).

15. The display device of claim 13 wherein the first notch reflector comprises a multi-layer, and the second notch reflector comprises a non-polarizing notch reflector and a quarter-wave plate.

16. The display device of claim 13 , further comprising a first variable focus lens disposed rearward of the first notch reflector and a second variable focus lens disposed forward of the second notch reflector, wherein second optical characteristics of the second variable focus lens compensate for first optical characteristics of the first variable focus lens.

17. The display device of claim 16 , wherein each of the first variable focus lens and the second variable focus lens comprises a linear polarization lens.

18. The display device of claim 16 , wherein each of the first variable focus lens and the second variable focus lens comprises a Pancharatnam-Berry (PB) phase lens.

19. The display device of claim 18 , further comprising a spatial offset compensator configured to compensate for a spatial offset introduced by the PB phase lenses.

Assignees

• Magic Leap Inc

Inventors

• Oh Chulwoo

Classifications

• G02F1/29

  for the control of the position or the direction of light beams, i.e. deflection · CPC title

• G02F1/137 Primary

  characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering · CPC title

• G02F1/13306

  Circuit arrangements or driving methods for the control of single liquid crystal cells (G02F1/132, G02F1/133382 take precedence) · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title

• G02B26/0825 Primary

  the reflecting element being a flexible sheet or membrane, e.g. for varying the focus (flexible mirrors for cosmetic use A45D42/24) · CPC title