Optical systems for providing polarized light to a waveguide

Patent metadata

Field	Value
Publication number	US-12442966-B2
Application number	US-202318188322-A
Country	US
Kind code	B2
Filing date	Mar 22, 2023
Priority date	Oct 15, 2020
Publication date	Oct 14, 2025
Grant date	Oct 14, 2025

Abstract

A display may include a waveguide for providing light to an eye box. The display may include polarization recycling structures having a polarizing beam splitter and a prism. The polarizing beam splitter may transmit a first portion of unpolarized light as first image light having a first polarization and may reflect a second portion of the unpolarized light as second image light having a second polarization. One or more waveplates may be mounted to the prism for transmitting the second image light. Upon transmission by the waveplate(s), the second image light may have the same polarization as the first image light. An input coupler may couple the first and second image light into the waveguide. Providing polarized light to the waveguide may maximize the optical efficiency of the waveguide. The polarization recycling structures may maximize the amount of the image light that is coupled into the waveguide.

First claim

What is claimed is:

1. A display system comprising:
a waveguide;
an input coupling prism mounted to the waveguide;
a polarizing beam splitter, wherein the polarizing beam splitter is configured to transmit a first portion of unpolarized image light as first image light having a first polarization and is configured to reflect a second portion of the unpolarized image light as second image light having a second polarization;
a prism having a reflective surface;
a first quarter waveplate optically interposed between the prism and the polarizing beam splitter; and
a second quarter waveplate optically interposed between the prism and the waveguide, wherein the first quarter waveplate is configured to transmit the second image light, the reflective surface is configured to reflect the second image light after transmission by the first quarter waveplate, the second quarter waveplate is configured to transmit the second image light after reflection by the reflective surface, and the input coupling prism is configured to couple the first and second image light into the waveguide.

2. The display system of claim 1 , wherein the second image light has the first polarization after transmission by the second quarter waveplate.

3. The display system of claim 2 , further comprising:
an output coupler on the waveguide, wherein the output coupler is configured to couple the first and second image light out of the waveguide.

4. The display system of claim 3 , wherein the output coupler comprises holograms.

5. The display system of claim 1 , wherein the input coupling prism has an additional reflective surface that is configured to receive the first and second image light through the waveguide and that is configured to reflect the first and second image light into the waveguide.

6. The display system of claim 5 , further comprising an air gap between the polarizing beam splitter and the waveguide and between the prism and the waveguide.

7. The display system of claim 1 , wherein the input coupling prism has a transmissive surface that is configured to receive the first and second image light and that is configured to transmit the first and second image light into the waveguide.

8. The display system of claim 7 , wherein the polarizing beam splitter and the prism are mounted to the transmissive surface of the input coupling prism.

9. The display system of claim 1 , wherein the polarizing beam splitter comprises a first additional prism, a second additional prism, and a reflective polarizer interposed between the first and second additional prisms, the first quarter waveplate being optically interposed between the prism and the first additional prism.

10. A display system comprising:
a waveguide;
an input coupling prism mounted to the waveguide;
a polarizing beam splitter, wherein the polarizing beam splitter is configured to transmit a first portion of unpolarized image light as first image light having a first polarization and is configured to reflect a second portion of the unpolarized image light as second image light having a second polarization;
a prism having a reflective surface; and
a half waveplate coupled to the prism, wherein the second image light is configured to reflect off of the reflective surface of the prism, the half waveplate is configured to transmit the second image light, and the input coupling prism is configured to couple the first and second image light into the waveguide.

11. The display system of claim 10 , wherein the prism has a first surface and a second surface orthogonal to the first surface, the reflective surface extends from the first surface to the second surface, the first surface is coupled to the polarizing beam splitter, and the first and second surfaces are configured to transmit the second image light.

12. The display system of claim 11 , wherein the half waveplate is layered on the first surface of the prism.

13. The display system of claim 11 , wherein the half waveplate is layered on the second surface of the prism.

14. The display system of claim 10 , further comprising:
an output coupler on the waveguide, wherein the output coupler is configured to couple the first and second image light out of the waveguide and wherein the output coupler comprises volume holograms.

15. The display system of claim 10 , wherein the input coupling prism has an additional reflective surface that is configured to receive the first and second image light through the waveguide, the first and second image light both have the first polarization when received at the additional reflective surface, and the additional reflective surface is configured to reflect the first and second image light into the waveguide.

16. The display system of claim 15 , further comprising an air gap between the polarizing beam splitter and the waveguide and between the prism and the waveguide.

17. The display system of claim 10 , wherein the input coupling prism has a transmissive surface that is configured to receive the first and second image light, the first and second image light both have the first polarization when received at the transmissive surface, and the transmissive surface is configured to transmit the first and second image light into the waveguide.

18. The display system of claim 17 , wherein the polarizing beam splitter and the prism are mounted to the transmissive surface of the input coupling prism.

19. An electronic device comprising:
a display module configured to produce unpolarized image light;
a waveguide having an output coupler;
a first prism;
a second prism;
a reflective polarizer interposed between the first and second prisms, wherein the reflective polarizer is configured to receive the unpolarized image light through the first prism, is configured to transmit a first portion of the unpolarized image light as first image light having a first linear polarization, and is configured to reflect a second portion of the unpolarized image light as second image light having a second linear polarization orthogonal to the first linear polarization;
a third prism coupled to the first prism, wherein the third prism is configured to receive the second image light through the first prism and is configured to reflect the second image light towards the waveguide;
a waveplate coupled to the third prism and configured to transmit the second image light; and
an input coupler on the waveguide, wherein the input coupler is configured to receive the first and second image light, the first and second image light both have the first linear polarization upon receipt by the input coupler, the input coupler is configured to couple the first and second image light into the waveguide, and the output coupler is configured to couple the first and second image light out of the waveguide.

20. The electronic device of claim 19 , further comprising:
an additional waveplate coupled to the third prism and configured to transmit the second image light, wherein the waveplate comprises a first quarter waveplate and the additional waveplate comprises a second quarter waveplate.

21. The electronic device of claim 19 , wherein the input coupler comprises an input coupler selected from the group consisting of: an input coupling prism, a surface relief grating, and a louvered mirror.

22. An electronic device comprising:
a display module configured to produce image light;
a waveguide having an output coupler;
a first prism;
a second prism;
a beam splitter interposed between the first an

Assignees

• Apple Inc

Inventors

• Bhakta Vikrant
• Peng Guolin
• Choi Hyungryul
• Delapp Scott M

Classifications

• G02B27/283

  used for beam splitting or combining · CPC title

• G02B6/0035

  provided on the surface of the light guide or in the bulk of it · CPC title

• G02B6/0031

  Reflecting element, sheet or layer · CPC title

• G02B5/32

  Holograms used as optical elements · CPC title

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title