Electronically-controllable polarization independent liquid crystal optical medium and devices using same
First Claim
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1. An optical device comprising:
- a light source;
an optical cell arranged to receive light from the light source, the optical cell containing a polymer-stabilized liquid crystal material including a substantially randomly oriented short-pitch cholesteric liquid crystal material having a pitch of less than 500 nm stabilized by a polymer material wherein (i) a concentration of the polymer material in the polymer-stabilized liquid crystal material and (ii) a highly twisted structure of the randomly oriented short-pitch cholesteric liquid crystal material cause the optical medium to interact with light received from the light source in a substantially polarization-independent manner and wherein the polymer material is less than about 25 wt-% of the polymer-stabilized liquid crystal material, the optical cell including electrodes for selectively applying a voltage across the polymer-stabilized liquid crystalline optical material; and
a voltage source arranged to apply voltage to the electrodes over an operative voltage range wherein the optical cell provides polarization-independent phase retardation as a function of voltage over the operative voltage range, the operative voltage range being not sufficient to switch the optical cell into a homeotropic state, the randomly oriented short-pitch cholesteric liquid crystal material remaining randomly oriented over the operative voltage range.
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Abstract
A liquid crystalline optical medium includes polymer stabilized liquid crystal material. The polymer stabilized liquid crystal material includes a short pitch cholesteric liquid crystal material stabilized by a polymer material. The effective phase retardation of the polarization independent liquid crystal optical medium can be controlled by external (for example, electric and magnetic) fields.
24 Citations
20 Claims
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1. An optical device comprising:
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a light source; an optical cell arranged to receive light from the light source, the optical cell containing a polymer-stabilized liquid crystal material including a substantially randomly oriented short-pitch cholesteric liquid crystal material having a pitch of less than 500 nm stabilized by a polymer material wherein (i) a concentration of the polymer material in the polymer-stabilized liquid crystal material and (ii) a highly twisted structure of the randomly oriented short-pitch cholesteric liquid crystal material cause the optical medium to interact with light received from the light source in a substantially polarization-independent manner and wherein the polymer material is less than about 25 wt-% of the polymer-stabilized liquid crystal material, the optical cell including electrodes for selectively applying a voltage across the polymer-stabilized liquid crystalline optical material; and a voltage source arranged to apply voltage to the electrodes over an operative voltage range wherein the optical cell provides polarization-independent phase retardation as a function of voltage over the operative voltage range, the operative voltage range being not sufficient to switch the optical cell into a homeotropic state, the randomly oriented short-pitch cholesteric liquid crystal material remaining randomly oriented over the operative voltage range. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An optical device comprising:
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a light source outputting light of wavelength or wavelength range greater than one micron; an optical cell arranged to receive light from the light source, the optical cell containing a polymer-stabilized liquid crystal material including a substantially randomly oriented short-pitch cholesteric liquid crystal material having a pitch of less than 500 nm stabilized by a polymer material wherein the short-pitch cholesteric liquid crystal material is arranged as domains having an average size of about one micron in the matrix of polymer material, the optical cell including electrodes for selectively applying a voltage across the polymer-stabilized liquid crystal material; and a voltage source arranged to apply voltage to the electrodes over an operative voltage range wherein the optical cell provides polarization-independent phase retardation as a function of voltage over the operative voltage range, the operative voltage range being not sufficient to switch the optical cell into a homeotropic state, the randomly oriented short-pitch cholesteric liquid crystal material remaining randomly oriented over the operative voltage range. - View Dependent Claims (9, 10, 11, 12)
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13. An optical device comprising:
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a light source; an optical cell arranged to receive light from the light source, the optical cell containing a polymer-stabilized liquid crystal material including a substantially randomly oriented short-pitch cholesteric liquid crystal material having a pitch of less than 500 nm arranged as domains and stabilized by a polymer material wherein (i) a concentration of the polymer material in the polymer-stabilized liquid crystal material and (ii) a highly twisted structure of the randomly oriented short-pitch cholesteric liquid crystal material cause the polymer-stabilized liquid crystal material to produce a substantially polarization-independent phase retardation of at least light received from the light source, the optical cell including electrodes for selectively applying a voltage across the polymer-stabilized liquid crystal material, wherein the liquid crystal material domains have a small average size as compared with the wavelength or wavelength range of light received from the light source; a voltage source arranged to apply voltage to the electrodes over an operative voltage range, wherein the optical cell provides polarization-independent phase retardation as a function of voltage over the operative voltage range, the operative voltage range being not sufficient to switch the optical cell into a homeotropic state light, the randomly oriented short-pitch cholesteric liquid crystal material remaining randomly oriented over the operative voltage range. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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Specification