Augmented reality display having liquid crystal variable focus element and roll-to-roll method and apparatus for forming the same
A display device includes a waveguide assembly comprising a waveguide configured to outcouple light out of a major surface of the waveguide to form an image in the eyes of a user. An adaptive lens assembly comprises a switchable waveplate assembly. The switchable waveplate assembly includes quarter-wave plates on opposing sides of a switchable liquid crystal layer, and electrodes on the quarter-wave plates in the volume between the quarter-wave plates. The electrodes can selectively establish an electric field and may serve as an alignment structure for molecules of the liquid crystal layer. Portions of the adaptive lens assembly may be manufactured by roll-to-roll processing in which a substrate roll is unwound, and alignment layers and liquid crystal layers are formed on the substrate as it moves towards a second roller, to be wound on that second roller.
1 . A display device comprising:
a waveguide assembly comprising a waveguide configured to output light to display an image; and
an adaptive lens assembly in a same optical path as the waveguide, the adaptive lens assembly comprising:
a switchable waveplate assembly comprising:
a first substrate and a second substrate defining a volume therebetween, wherein the first substrate is a first quarter-wave plate and the second substrate is a second quarter-wave plate, and wherein the first substrate and the second substrate are composed of a non-liquid crystal material that is optically transmissive and pliable;
a liquid crystal layer disposed within the volume;
a first set of guides for aligning liquid crystal molecules of the liquid crystal layer, the first set of guides comprising a first electrode pattern disposed in the volume and directly on the first substrate; and
a second set of guides for aligning the liquid crystal molecules of the liquid crystal layer, the second set of guides comprising a second electrode pattern disposed in the volume and directly on the second substrate;
wherein the first electrode pattern and the second electrode pattern extend into the liquid crystal layer and are configured to selectively apply an electric field for selectively changing orientations of liquid crystal molecules in the liquid crystal layer.
2 . The display device of claim 1 , wherein at least one of the first electrode pattern and the second electrode pattern comprises an array of parallel conductors.
3 . The display device of claim 1 , wherein at least one of the first electrode pattern and the second electrode pattern comprises a wire mesh.
4 . The display device of claim 1 , wherein the adaptive lens assembly has a major surface facing a major surface of the waveguide.
5 . The display device of claim 1 , wherein the adaptive lens assembly further comprises a waveplate lens comprising a liquid crystal polymer layer.
6 . The display device of claim 5 , wherein the adaptive lens assembly further comprises an alignment layer disposed between the waveplate lens and the first quarter- wave plate, wherein the alignment layer at least partially determines orientations of the liquid crystal molecules in the liquid crystal polymer layer.
7 . The display device of claim 1 , further comprising a second adaptive lens assembly on the opposite side of the waveguide assembly from the adaptive lens assembly, wherein the second adaptive lens assembly comprises a second switchable waveplate assembly comprising a second liquid crystal polymer layer.
8 . The display device of claim 1 , wherein the display device is configured to be worn by a user, and wherein:
the adaptive lens assembly is on a user side of the waveguide assembly and applying the electric field causes the adaptive lens assembly to provide negative optical power to light passing through the adaptive lens assembly, or
the adaptive lens assembly is on a world side of the waveguide assembly and applying the electric field causes the adaptive lens assembly to provide positive optical power to light passing through the adaptive lens assembly.
9 . The display device of claim 1 , wherein the adaptive lens assembly has a thickness between about 1 mm and about 3 mm.
10 . The display device of claim 1 , wherein the switchable waveplate assembly further comprises an optically transmissive cap material comprising a metal or an ionic compound overlying at least a portion of the first electrode pattern or the second electrode pattern.
11 . The display device of claim 10 , wherein the cap material comprises an anti-reflective coating.
12 . The display device of claim 1 , wherein:
the adaptive lens assembly provides substantially zero optical power to light passing through the adaptive lens assembly, when the electric field is not applied, and
the adaptive lens assembly provides positive optical power or a negative optical power to light passing through the adaptive lens assembly, when the electric field is applied.
13 . An adaptive lens assembly comprising:
a switchable waveplate assembly comprising:
a first substrate and a second substrate defining a volume therebetween, wherein the first substrate is a first quarter-wave plate and the second substrate is a second quarter-wave plate, and wherein the first substrate and the second substrate are composed of a non-liquid crystal material that is optically transmissive and pliable;
a liquid crystal layer disposed within the volume;
a first set of guides for aligning liquid crystal molecules of the liquid crystal layer, the first set of guides comprising a first electrode pattern disposed in the volume and directly on the first substrate; and
a second set of guides for aligning the liquid crystal molecules of the liquid crystal layer, the second set of guides comprising a second electrode pattern disposed in the volume and directly on the second substrate;
wherein the first electrode pattern and the second electrode pattern extend into the liquid crystal layer and are configured to selectively apply an electric field for selectively changing orientations of liquid crystal molecules in the liquid crystal layer.
14 . The adaptive lens assembly of claim 13 , wherein at least one of the first electrode pattern and the second electrode pattern comprises an array of parallel conductors.
15 . The adaptive lens assembly of claim 13 , wherein at least one of the first electrode pattern and the second electrode pattern comprises a wire mesh.
16 . The adaptive lens assembly of claim 13 , further comprising a waveplate lens comprising a liquid crystal polymer layer.
17 . The adaptive lens assembly of claim 16 , wherein the adaptive lens assembly further comprises an alignment layer disposed between the waveplate lens and the first quarter-wave plate, wherein the alignment layer at least partially determines orientations of the liquid crystal molecules in the liquid crystal polymer layer.
18 . The adaptive lens assembly of claim 13 , wherein the first electrode pattern and the second electrode pattern each comprise:
a layer disposed on the first or second substrate and comprising a plurality of protrusions extending into the volume; and
a layer of conductive material conformally disposed on at least a portion of the plurality of protrusions.
19 . The adaptive lens assembly of claim 13 , wherein the switchable waveplate assembly further comprises an optically transmissive cap material comprising a metal or an ionic compound overlying at least a portion of the first electrode pattern or the second electrode pattern.
20 . The adaptive lens assembly of claim 19 , wherein the cap material comprises an anti-reflective coating.