Switchable volume hologram materials and devices
First Claim
1. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
- (a) a polymerizable monomer comprising a plurality of acrylates;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye.
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Accused Products
Abstract
A new photopolymerizable material allows single-step, fast recording of volume holograms with properties that can be electrically controlled. Polymer-dispersed liquid crystals (PDLCs) in accordance with the invention preferably comprise a homogeneous mixture of a nematic liquid crystal and a multifunctional pentaacrylate monomer, in combination with photoinitiator, coinitiator and cross-linking agent. Optionally, a surfactant such as octanoic acid may also be added. The PDLC material is exposed to coherent light to produce an interference pattern inside the material. Photopolymerization of the new PDLC material produces a hologram of clearly separated liquid crystal domains and cured polymer domains. Volume transmission gratings made with the new PDLC material can be electrically switched between nearly 100% diffraction efficiency and nearly 0% diffraction efficiency. By increasing the frequency of the switching voltage, switching voltages in the range of 50 Vrms can be achieved. The optional use of surfactant allows low switching voltages at lower frequencies than without surfactant. In an alternative embodiment, a PDLC material in accordance with the invention can be utilized to form reflection gratings, including switchable reflection gratings. In still further embodiments, a PDLC material in accordance with the invention can be used to form switchable subwavelength gratings. By further processing, static transmission reflection, and subwavelength PDLC materials can be formed.
196 Citations
40 Claims
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1. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer comprising a plurality of acrylates;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal comprising ∝
-methoxybenzylidene-4′
-butylaniline;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye.
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11. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye comprising 2,4,5,7-tetraiodo-3′
,4′
,5′
,6′
-tetrachlorofluroescein-6-acetate ester.
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12. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye selected from the group consisting of eosin, eosin sodium salt, 4,5-diiodosuccinyl fluorescein, camphorquinone and methylene blue.
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13. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye comprising a cationic cyanine dye.
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14. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator; and
(e) a photoinitiator dye comprising a merocyanine dye.
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15. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator comprising triethyl amine; and
(e) a photoinitiator dye.
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16. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator comprising triethanolamine; and
(e) a photoinitiator dye. - View Dependent Claims (22, 23, 24, 25)
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17. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator comprising N,N-dimethyl-2,6-diisopropyl aniline; and
(e) a photoinitiator dye.
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18. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator comprising an organic borate; and
(e) a photoinitiator dye. - View Dependent Claims (19, 20, 21)
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26. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator comprising triphenyl borate; and
(e) a photoinitiator dye comprising indolinocarbocyanine.
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27. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator comprising triethylamine; and
(e) a photoinitiator dye comprising iodobenzospiropyran.
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28. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator comprising trialkylborate; and
(e) a photoinitiator dye comprising a cationic cyanine dye.
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29. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer comprising N-vinyl pyridine;
(d) a coinitiator; and
(e) a photoinitiator dye.
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30. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer comprising acrylonitrile;
(d) a coinitiator; and
(e) a photoinitiator dye.
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31. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer comprising N-vinyl carbazole;
(d) a coinitiator; and
(e) a photoinitiator dye.
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32. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) a liquid crystal;
(c) a cross-linking monomer;
(d) a coinitiator;
(e) a photoinitiator dye; and
(f) a surfactant selected from the group consisting of heptanoic acid, hexanoic acid, dodecanoic acid, and decanoic acid.
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33. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable monomer;
(b) vinyl neononanoate;
(c) a liquid crystal;
(d) a coinitiator; and
(e) a photoinitiator dye. - View Dependent Claims (34, 35)
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36. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable liquid crystal monomer;
(b) a liquid crystal;
(c) a coinitiator; and
(d) a photoinitiator dye. - View Dependent Claims (37, 38, 39)
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40. A hologram made by exposing an interference pattern inside a polymer-dispersed liquid crystal material, the polymer-dispersed liquid crystal material comprising, before exposure:
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(a) a polymerizable semifluorinated acrylate monomer;
(b) a liquid crystal;
(c) a coinitiator; and
(d) a photoinitiator dye.
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Specification