Pupil Expansion

Patent metadata

Field	Value
Publication number	US-2025284123-A1
Application number	US-202519212437-A
Country	US
Kind code	A1
Filing date	May 19, 2025
Priority date	Feb 19, 2020
Publication date	Sep 11, 2025
Grant date	—

Abstract

There is disclosed herein a waveguide including an optical slab and an optical wedge. The optical slab has a first refractive index, n 1 >1. The optical slab includes: a pair of opposing surfaces and an input port. The pair of opposing surfaces are arranged in a parallel configuration. The input port is arranged to receive light into the optical slab at an angle such that the light is guided between the first and second opposing surfaces. The optical wedge has a second refractive index, n 2 , wherein 1<n 2 <n 1 . The optical wedge includes a pair of opposing surfaces arranged in a wedge configuration. A first surface of the optical wedge abuts the second surface of the optical slab to form an interface. The angle of the wedge allows light received at the interface to escape through the second surface of the optical wedge such that the exit pupil of the waveguide is expanded.

First claim

1 - 20 . (canceled)

21 . A waveguide device comprising:
an optical waveguide layer having a first refractive index, n 1 >1, wherein the optical waveguide layer comprises opposing first and second surfaces, the optical waveguide layer being configured to guide light between the first and second opposing surfaces along a propagation path in a propagation direction from an input of the optical waveguide layer; and an optical wedge having a second refractive index, n 2 , wherein 1<n 2 <n 1 , the optical wedge comprising opposing first and second surfaces arranged in a wedge configuration, the first surface of the optical wedge abutting the second surface of the optical waveguide layer,
wherein
the first surface of the optical wedge and the second surface of the optical waveguide layer form an interface configured to allow partial transmission of light guided by the optical waveguide layer along the propagation path into the optical wedge at a plurality of points along the interface such that the light is divided a plurality of times;
an angle of the wedge allows the divided light transmitted through the interface into the optical wedge to escape through the second surface of the optical wedge such that the exit pupil of the waveguide device is expanded by the plurality of divisions of the light; and
the thickness of the optical wedge decreases with distance along the propagation path in the propagation direction.

22 . The waveguide device as claimed in claim 21 , wherein the refractive index of the optical wedge decreases with distance along the propagation path in the propagation direction.

23 . The waveguide device as claimed in claim 21 , further comprising an index matching fluid layer sandwiched between the optical waveguide layer and optical wedge, wherein the refractive index of the index matching fluid decreases with distance along the propagation path in the propagation direction.

24 . The waveguide device as claimed in claim 21 , further comprising an output port arranged to eject light from the optical waveguide layer.

25 . The waveguide device as claimed in claim 21 , wherein a thickness of the optical wedge decreases linearly with distance along the propagation path in the propagation direction.

26 . The waveguide device as claimed in claim 21 , wherein the second surface of the optical wedge tapers along the propagation path in the propagation direction to meet the first surface at a point or apex.

27 . The waveguide device as claimed in claim 21 , wherein second surface of the optical wedge is curved.

28 . The waveguide device as claimed in claim 27 , wherein an angle between the opposing first and second surfaces of the optical wedge decreases along the propagation path in the propagation direction.

29 . A display system comprising
a picture generating unit arranged to display a pattern; and the waveguide device of claim 21 , arranged to
receive light of the pattern from the picture generating unit, guide the light of the pattern along the propagation path from an input thereof,
allow the partial transmission of the light of the pattern guided by the optical waveguide layer along the propagation path into the optical wedge at the plurality of points along the interface such that the light is divided a plurality of times, and
allow the divided light of the pattern transmitted through the interface into the optical wedge to escape through the second surface of the optical wedge such that the exit pupil of the waveguide device is expanded by the plurality of divisions.

30 . The display system as claimed in claim 29 , further comprising an optical system between the picture generating unit and the waveguide device, wherein the optical system comprising at least one selected from the group comprising: a collimation lens, and a pair of lens arranged to form a telescope.

31 . The display system as claimed in claim 29 , wherein the picture generating unit comprises a holographic projector.

32 . The display system as claimed in claim 31 , configured as a direct-view holographic system.

33 . A head-up display comprising the display system as claimed in claim 29 , and a windscreen positioned to reflect divided light of the pattern escaping through the second surface of the optical wedge to an eye-box.

34 . A method of pupil expansion, the method comprising:
providing a waveguide device comprising
an optical waveguide layer having a first refractive index, n 1 >1, wherein the optical waveguide layer comprises opposing first and second surfaces; and
an optical wedge having a second refractive index, n 2 , wherein 1<n 2 <n 1 , the optical wedge comprising opposing first and second surfaces arranged in a wedge configuration, the first surface of the optical wedge abutting the second surface of the optical waveguide layer,
guiding light between the opposing first and second surfaces of the optical waveguide layer along a propagation path in a propagation direction from an input; partially transmitting the guided light into the optical wedge at a plurality of points along an interface between the first surface of the optical wedge and the second surface of the optical waveguide layer, thereby dividing the guided light a plurality of times at the interface; and allowing the divided light transmitting through the interface into the optical wedge to from the optical wedge through the second surface of the optical wedge, wherein an angle of the wedge is such that the exit pupil of the waveguide is expanded by the plurality of divisions of the light.

35 . The method as claimed in claim 34 , wherein the light is light of a pattern, the method further comprising receiving the light of the pattern at an input of the waveguide layer.

36 . The method as claimed in claim 35 , wherein the light of the pattern is received from a holographic display.

37 . The method as claimed in claim 34 , further comprising reflecting divided light of the pattern escaping through the second surface of the optical wedge to an eye-box.

38 . The method as claimed in claim 34 , wherein the refractive index of the optical wedge decreases with distance along the propagation path in the propagation direction.

39 . The method as claimed in claim 34 , wherein the waveguide device further comprising an index matching fluid layer sandwiched between the optical waveguide layer and optical wedge, wherein the refractive index of the index matching fluid decreases with distance along the propagation path in the propagation direction.

40 . The method as claimed in claim 34 , further comprising ejecting light from the optical waveguide layer via an output thereof.

Assignees

• Envisics Ltd

Inventors

• Christmas Jamieson

Classifications

• G02B2027/0125

  Field-of-view increase by wavefront division · CPC title

• G02B27/0081 Primary

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

• G02B6/003

  Lens or lenticular sheet or layer · CPC title

• G02B6/002

  by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces · CPC title

• G03H2001/0216

  Optical components (G03H2001/0224, G03H1/0256 take precedence; corresponding details, see subgroups of G03H2223/00) · CPC title