Broadband adaptive lens assembly for augmented reality display

1. An integrated broadband adaptive lens assembly for a display, comprising:

a first electrode, a second electrode and a liquid crystal (LC) layer stack interposed between the first electrode and the second electrode,

wherein the LC layer stack comprises:

a switchable liquid crystal (LC) layer comprising unpolymerized LC molecules interposed between first and second polymerized LC layers each comprising polymerized LC molecules,

wherein LC molecules in the switchable LC layer that are adjacent to LC molecules in the first polymerized LC layer are generally elongated in a first direction,

wherein LC molecules in the switchable LC layer that are adjacent to LC molecules in the second polymerized LC layer are generally elongated in a second direction crossing the first direction,

wherein the switchable LC layer comprises LC molecules configured such that under a first voltage condition across the first and second electrodes, a polarization of incident light passing therethrough is preserved, while under a second voltage condition across the first and second electrodes, the polarization of the incident light passing therethrough is altered, and

wherein the switchable LC layer directly contacts each of the first and second polymerized LC layers without an intervening alignment layer.

2. The integrated broadband adaptive lens assembly of claim 1 , wherein the switchable LC layer comprises twisted nematic LC molecules having a net twist angle at about 90 degrees, such that under the second voltage condition, the switchable LC layer converts linearly polarized light having a first polarization direction into linearly polarized light having a second polarization direction perpendicular to the first direction.

3. The integrated broadband adaptive lens assembly of claim 2 , wherein each of the first and second polymerized LC layers comprises twisted nematic LC molecules and serves as a quarter wave plate.

4. The integrated broadband adaptive lens assembly of claim 2 , wherein the LC layer stack comprises a plurality of polymerized LC layers formed on opposing sides of the switchable LC layer, wherein each of the polymerized LC layers forms an interface with an adjacent one of the polymerized LC layers, and wherein LC molecules adjacent to the interface in the each of the polymerized LC layers are generally elongated in the same direction as LC molecules adjacent to the interface in the adjacent one of the polymerized LC layers.

5. The integrated broadband adaptive lens assembly of claim 1 , wherein the LC molecules of each of the switchable LC layer and the first and second polymerized LC layers are arranged such that a birefringence (Δn) of the LC molecules varies in a radially outward direction from a central region.

6. The integrated broadband adaptive lens assembly of claim 5 , wherein the Δn increases with increasing wavelength (λ) within a wavelength range including at least 450 nm to 630 nm.

7. The integrated broadband adaptive lens assembly of claim 5 , wherein the LC layer stack comprises two switchable LC layers each comprising twisted nematic LC molecules that are successively twisted in a layer normal direction.

8. The integrated broadband adaptive lens assembly of claim 7 , wherein the twisted nematic LC molecules of the two switchable LC layers are symmetrically twisted with respect to an interface formed between the two switchable LC layers by a net angle between about 60 degrees and 80 degrees.

9. The integrated broadband adaptive lens assembly of claim 5 , wherein the switchable LC layer comprises twisted nematic LC molecules configured such that under the second voltage condition, the switchable LC layer serves as a half waveplate.

10. The integrated broadband adaptive lens assembly of claim 5 , wherein each of the first and second polymerized LC layers comprises twisted nematic LC molecules and serves as a half wave plate.

11. An adaptive lens assembly comprising:

one or more waveplate lenses and one or more switchable waveplates aligned in a stack in an optical path,

wherein each of the one or more waveplate lenses is configured to diffract outcoupled light at a diffraction efficiency greater than 90% within a wavelength range including at least 450 nm to 630 nm, to alter a polarization state of light passing therethrough, to provide a first optical power for light having a first polarization, and to provide a second optical power for light having a second polarization,

wherein each of the one or more switchable waveplates is 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 and is selectively switchable between:

a first state configured to pass the light therethrough without altering a polarization state of the light; and

a second state configured to alter the polarization state of the light passing therethrough,

wherein each of the one or more waveplate lenses comprise polymerized LC layers each comprising polymerized LC molecules,

wherein each of the one or more switchable waveplates comprise a switchable liquid crystal (LC) layer comprising unpolymerized LC molecules, and

wherein the switchable LC layer of each of the one or more switchable waveplates directly contacts each of opposing polymerized LC layers of the waveplate lenses without an intervening alignment layer.

12. The adaptive lens assembly of claim 11 , wherein each of the one or more switchable waveplates in the second state is a half waveplate configured to invert a handedness of circularly polarized light.

13. The adaptive lens assembly of claim 11 , wherein each of the switchable waveplates is interposed between a pair of the one or more waveplate lenses.

14. The adaptive lens assembly of claim 13 , wherein the adaptive lens assembly comprises a plurality of the waveplate lenses and a plurality of the switchable waveplates, wherein the waveplate lenses and the switchable waveplates are alternatingly stacked.