Broadband adaptive lens assembly for augmented reality display

Patent metadata

Field	Value
Publication number	US-11960165-B2
Application number	US-202217582845-A
Country	US
Kind code	B2
Filing date	Jan 24, 2022
Priority date	Oct 26, 2017
Publication date	Apr 16, 2024
Grant date	Apr 16, 2024

Abstract

A display device comprises a waveguide configured to guide light in a lateral direction parallel to an output surface of the waveguide. The waveguide is further configured to outcouple the guided light through the output surface. The display device additionally comprises a broadband adaptive lens assembly configured to incouple and to diffract therethrough the outcoupled light from the waveguide. The broadband adaptive lens assembly comprises a first waveplate lens comprising a liquid crystal (LC) layer arranged such that the waveplate lens has birefringence (Δn) that varies in a radially outward direction from a central region of the first waveplate lens and configured to diffract the outcoupled light at a diffraction efficiency greater than 90% within a wavelength range including at least 450 nm to 630 nm. The broadband adaptive lens assembly is configured to be selectively switched between a plurality of states having different optical powers.

First claim

What is claimed is:

1. A broadband adaptive lens assembly for a display device, comprising:
a first waveplate lens comprising a liquid crystal (LC) layer having LC molecules arranged such that the first waveplate lens has birefringence (Δn) that varies in a radially outward direction from a central region of the first waveplate lens and configured to diffract light at a diffraction efficiency greater than 90% within a wavelength in a range spanning at least 450 nm to 630 nm, and wherein the Δn of the LC layer increases with increasing wavelength within the wavelength range; and
a switchable waveplate configured to be electrically activated and deactivated,
wherein the broadband adaptive lens assembly is configured to be selectively switched between at least two lens states including:
a first lens state configured to exert a first lens effect according to a first optical power and to alter a polarization of light passing through the broadband adaptive lens assembly; and
a second lens state configured to exert a second lens effect according to a second optical power and to preserve the polarization of the light passing through the broadband adaptive lens assembly.

2. The broadband adaptive lens assembly of claim 1 , wherein the switchable waveplate is a switchable half waveplate (HWP) configured to reverse the handedness of a circular polarized light when deactivated, while preserving the handedness of the circular polarized light when activated.

3. The broadband adaptive lens assembly of claim 2 , wherein the switchable HWP comprises a twisted nematic liquid crystal (TN LC) switch, wherein the TN LC switch comprises a switchable TN LC layer and is configured to reverse the polarization of a linearly polarized light when electrically deactivated, and to preserve the polarization of the linearly polarized light when electrically activated, and wherein the switchable TN LC layer comprises a plurality of elongated nematic LC molecules having twist angles that vary in a layer normal direction of the switchable TN LC layer.

4. The broadband adaptive lens assembly of claim 3 , wherein the switchable TN LC switch comprises the switchable TN LC layer formed between an upper alignment layer and a lower alignment layer, wherein the upper alignment layer is configured to align a director of the elongated nematic LC molecules that are immediately adjacent to the upper alignment layer in a first lateral direction, and wherein the lower alignment layer is configured to align a director of the elongated nematic LC molecules that are immediately adjacent to the lower alignment layer in a second lateral direction crossing the first lateral direction.

5. The broadband adaptive lens assembly of claim 4 , wherein one or both of the upper alignment layer and the lower alignment layer comprise a polymer layer comprising polyimide or polyamide.

6. The broadband adaptive lens assembly of claim 4 , wherein one or both of the upper alignment layer and the lower alignment layer comprise patterned nanostructures.

7. The broadband adaptive lens assembly of claim 6 , wherein the one or both of the upper alignment layer and the lower alignment layer serve as an electrode or electrodes configured to apply an electric field across the switchable TN LC layer.

8. The broadband adaptive lens assembly of claim 3 , wherein the TN LC switch comprises a pair of interlaced first and second electrodes on one side of the switchable TN LC layer, wherein the TN LC switch is configured to be switched by applying an electric field between the pair of interlaced first and second electrodes.

9. The broadband adaptive lens assembly of claim 3 , wherein the switchable half waveplate (HWP) comprises the TN LC switch interposed between a pair of broadband quarter waveplate (QWP) stacks.

10. The broadband adaptive lens assembly of claim 9 , wherein each of the broadband QWP stacks comprises a plurality of directly stacked polymerized TN LC layers.

11. The broadband adaptive lens assembly of claim 3 , wherein the switchable HWP comprises the switchable TN LC layer that is directly interposed between a pair of one or more polymerized TN LC layers, wherein the polymerized TN LC layers contacting the switchable TN LC layer serve as alignment layers for aligning the elongated nematic LC molecules of the switchable TN LC layer.

12. The broadband adaptive lens assembly of claim 10 , wherein each of the directly stacked polymerized TN LC layers has a thickness across which the elongated nematic LC molecules that are twisted by a twist angle, wherein adjacent ones of the directly stacked TN LC layers have different twist angles.

13. The broadband adaptive lens assembly of claim 1 , wherein the broadband adaptive lens assembly further comprises a second waveplate lens comprising a second liquid crystal (LC) layer having LC molecules arranged such that the second waveplate lens has birefringence (Δn) that varies in a radially outward direction from a central region of the second waveplate lens and configured to diffract light at a diffraction efficiency greater than 90% within a wavelength in a range spanning at least 450 nm to 630 nm, wherein the switchable waveplate is interposed between the first waveplate lens and the second waveplate lens.

14. A broadband adaptive lens assembly for a display device, comprising:
a first waveplate lens comprising a liquid crystal (LC) layer formed on a substrate, wherein the LC layer has LC molecules that are arranged such that the first waveplate lens has birefringence (Δn) that varies in a radially outward direction from a central region of the LC layer and configured to diffract light at a diffraction efficiency greater than 90% within a wavelength range spanning at least 450 nm to 630 nm, wherein ones of the LC molecules that are the closest to the substrate have generally the same orientation direction at different locations at the same radius from the central region, and wherein the Δn of the LC layer increases with increasing wavelength within the wavelength range,
wherein the broadband adaptive lens assembly is configured to be selectively switched between at least two lens states including:
a first lens state configured to exert a first lens effect according to a first optical power and to alter a polarization of light passing through the broadband adaptive lens assembly; and
a second lens state configured to exert a second lens effect according to a second optical power and to preserve the polarization of the light passing through the broadband adaptive lens assembly.

15. The broadband adaptive lens assembly of claim 14 , wherein the LC layer is arranged in a plurality of concentric zones, wherein each of the concentric zones has a range of radius within which the ones of the LC molecules that are the closest to the substrate have generally the same orientation direction.

16. The broadband adaptive lens assembly of claim 15 , wherein the ones of the LC molecules that are the closest to the substrate have azimuthal twist angles that vary with radius according to a mathematical function.

17. The broadband adaptive lens assembly of claim 14 , wherein ones of the LC molecules that are within the same concentric zone have generally the same twist angle at different depths of the LC layer.

18. The broadband adaptive lens assembly of claim 14 , wherein the first waveplate lens comprises a plurality of LC layers, each of the LC layers comprising LC molecules that are successively twisted in a layer normal direction.

19. The broadband adaptive lens assembly of claim 18 , wh

Assignees

• Magic Leap Inc

Inventors

• Oh Chulwoo
• Komanduri Ravi Kumar
• Patterson Roy Matthew
• Carden Charles Scott
• Miller Michael Nevin
• Singh Vikramjit

Classifications

• G02B5/1833

  comprising birefringent materials (birefringent elements per se G02B5/3083) · CPC title

• G02B5/3016

  involving passive liquid crystal elements (optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528) · CPC title

• G02F1/133526 Primary

  Lenses, e.g. microlenses or Fresnel lenses · CPC title

• G02B1/00

  Optical elements characterised by the material of which they are made; Optical coatings for optical elements · CPC title

• G02B5/30

  Polarising elements (light-modulating devices with active elements G02F1/00) · CPC title