Anamorphic directional illumination device with selective light-guiding

Patent metadata

Field	Value
Publication number	US-12282168-B2
Application number	US-202318232048-A
Country	US
Kind code	B2
Filing date	Aug 9, 2023
Priority date	Aug 11, 2022
Publication date	Apr 22, 2025
Grant date	Apr 22, 2025

Abstract

An anamorphic directional illumination device may provide a near-eye display apparatus or a vehicle external light device. The anamorphic near-eye display apparatus comprises a spatial light modulator with asymmetric pixels; an input transverse anamorphic lens; and an extraction waveguide that passes input light in a first direction between a polarization-sensitive reflector and front guide surface to a lateral anamorphic reflector, and to reflect the light back through the extraction waveguide to guide between the rear guide surface and front guide surface. Reflective extraction features are arranged to extract the reflected light towards the pupil of a viewer, maintaining the directionality of the fan of light rays from the spatial light modulator and anamorphic imaging system. A thin, transparent and efficient anamorphic display apparatus for Augmented Reality and Virtual Reality displays and for scene illumination is provided.

First claim

The invention claimed is:

1. An anamorphic near-eye display apparatus comprising:
an illumination system comprising a spatial light modulator, the illumination system being arranged to output light; and
an optical system arranged to direct light from the illumination system to a viewer's eye, wherein the optical system has an optical axis and has anamorphic properties in a lateral direction and a transverse direction that are perpendicular to each other and perpendicular to the optical axis, wherein the spatial light modulator comprises pixels distributed in the lateral direction, and the optical system comprises:
a transverse anamorphic component having positive optical power in the transverse direction, wherein the transverse anamorphic component is arranged to receive light from the spatial light modulator and the illumination system is arranged so that light output from the transverse anamorphic component is directed in directions that are distributed in the transverse direction;
an extraction waveguide arranged to receive light from the transverse anamorphic component;
a lateral anamorphic component having positive optical power in the lateral direction, the extraction waveguide being arranged to guide light from the transverse anamorphic component to the lateral anamorphic component along the extraction waveguide in a first direction; and
a light reversing reflector that is arranged to reflect light guided along the extraction waveguide in the first direction to form light that is guided along the extraction waveguide in a second direction opposite to the first direction,
wherein:
the extraction waveguide comprises:
a front guide surface;
a polarization-sensitive reflector opposing the front guide surface; and
an extraction element disposed outside the polarization-sensitive reflector,
the extraction element comprising:
a rear guide surface opposing the front guide surface; and an array of extraction features;
the anamorphic near-eye display apparatus is arranged to provide light guided along the extraction waveguide in the first direction with an input linear polarization state before reaching the polarization-sensitive reflector; and
the optical system further comprises a polarization conversion retarder disposed between the polarization-sensitive reflector and the light reversing reflector, wherein the polarization conversion retarder is arranged to convert a polarization state of light passing therethrough between a linear polarization state and a circular polarization state, and the polarization conversion retarder and the light reversing reflector are arranged in combination to rotate the input linear polarization state of the light guided in the first direction so that the light guided in the second direction and output from the polarization conversion retarder has an orthogonal linear polarization state that is orthogonal to the input linear polarization state;
the polarization-sensitive reflector is arranged to reflect light guided in the first direction having the input linear polarization state and to pass light guided in the second direction having the orthogonal linear polarization state, so that the front guide surface and the polarization-sensitive reflector are arranged to guide light in the first direction, and the front guide surface and the rear guide surface are arranged to guide light in the second direction; and
the array of extraction features is arranged to extract light guided along the extraction waveguide in the second direction towards an eye of a viewer through the front guide surface, the array of extraction features being distributed along the extraction waveguide so as to provide exit pupil expansion in the transverse direction;
wherein the polarization conversion retarder has a retardance of a quarter wavelength at a wavelength of visible light.

2. An anamorphic near-eye display apparatus according to claim 1 , wherein the polarization-sensitive reflector comprises a reflective linear polarizer.

3. An anamorphic near-eye display apparatus according to claim 1 , wherein the input linear polarization state is a p-polarization state in the extraction waveguide, or the input linear polarization state is an s-polarization state in the extraction waveguide.

4. An anamorphic near-eye display apparatus according to claim 1 , wherein the optical system further comprises an input linear polarizer that is disposed between the spatial light modulator and the polarization-sensitive reflector and is arranged to pass light having the input linear polarization state.

5. An anamorphic near-eye display apparatus according to claim 4 , wherein the input linear polarizer is disposed between the spatial light modulator and the extraction waveguide.

6. An anamorphic near-eye display apparatus according to claim 4 , wherein the input linear polarizer is disposed within the extraction waveguide.

7. An anamorphic near-eye display apparatus according to claim 4 , wherein the input linear polarizer is disposed after the transverse anamorphic component, and the optical system further comprises a polarization conversion retarder disposed between the transverse anamorphic component and the input linear polarizer, the polarization conversion retarder being arranged to convert a polarization state of light passing therethrough between a linear polarization state and a circular polarization state.

8. An anamorphic near-eye display apparatus according to claim 4 , wherein the illumination system is arranged to output light that is unpolarized.

9. An anamorphic near-eye display apparatus according to claim 1 , wherein the illumination system is arranged to output light having the input linear polarization state.

10. An anamorphic near-eye display apparatus according to claim 1 , wherein the extraction features are elongate in the lateral direction.

11. An anamorphic near-eye display apparatus according to claim 1 , wherein the rear guide surface comprises extraction facets that are the extraction features, each extraction facet being arranged to reflect light guided in the second direction towards an eye of a viewer through the front guide surface.

12. An anamorphic near-eye display apparatus according to claim 11 , wherein the rear guide surface comprises plural prisms that protrude outwardly, the prisms each comprising at least one extraction facet and at least one draft facet.

13. An anamorphic near-eye display apparatus according to claim 12 , wherein at least one of the prisms comprises plural draft facets, and an intermediate guide facet arranged between each adjacent pair of the plural draft facets.

14. An anamorphic near-eye display apparatus according to claim 12 , wherein the prisms each further comprise a primary guide facet between the at least one extraction facet and the at least one draft facet.

15. An anamorphic near-eye display apparatus according to claim 12 , wherein the rear guide surface comprises guide portions between the prisms.

16. An anamorphic near-eye display apparatus according to claim 1 , wherein the rear guide surface comprises a surface relief grating comprising the extraction features.

17. An anamorphic near-eye display apparatus according to claim 1 , wherein the extraction element comprises an array of extraction reflectors disposed internally within the extraction waveguide.

18. An anamorphic near-eye display apparatus according to claim 17 , wherein the array of extraction reflectors is arranged between the polarization-sensitive reflector and the rear light guide surface.

19. An anamorp

Assignees

• Reaid Spark Llc
• Reald Spark Llc

Inventors

• Robinson Michael G
• Woodgate Graham J
• Harrold Jonathan
• Wilson Austin

Classifications

• F21S43/2605

  Refractors · CPC title

• G02B27/288

  Filters employing polarising elements, e.g. Lyot or Solc filters (G02B5/3016 takes precedence) · CPC title

• G02B5/0825

  the reflecting layers comprising dielectric materials only · 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

• G02B27/0081 Primary

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