Chiral smectic liquid crystal optical modulators having variable retardation
First Claim
1. A variable retarder for elliptically polarized light comprising:
- a first half-wave plate comprising a first planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis;
means for applying an electric field across said liquid crystal cell to rotate said optic axis; and
first and second quarter-wave plates positioned in series with and on either side of said half-wave plate, the optic axes of said quarter-wave plates oriented parallel or perpendicular to each other;
wherein the combination of said half-wave plate with said quarter-wave plates produces a retardance which is varied by rotation of said rotatable optic axis; and
wherein the polarization of said incoming light may be oriented at any angle with respect to the optic axis of said first quarter-wave plate, except for linearly polarized light oriented at ±
45°
.
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Accused Products
Abstract
The present invention provides optical modulators which comprise aligned chiral smectic liquid crystal cells within an optical resonance cavity. The cavity configurations include symmetric and asymmetric Fabry-Perot etalons. The liquid crystal cells can be planar- or homeotropically-aligned and can be discrete state or analog cells. The device configurations of the present invention provide discrete or continuous optical modulation of the phase, intensity, and wavelength of elliptically polarized light, without requiring polarization analyzers. The modulators are optically or electronically addressable in single pixels or arrays of multiple pixels. Certain homeotropically-aligned cells are provided as an aspect of this invention, as are certain variable retarders comprised of planar-aligned cells in combination with birefringent elements.
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Citations
74 Claims
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1. A variable retarder for elliptically polarized light comprising:
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a first half-wave plate comprising a first planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and first and second quarter-wave plates positioned in series with and on either side of said half-wave plate, the optic axes of said quarter-wave plates oriented parallel or perpendicular to each other; wherein the combination of said half-wave plate with said quarter-wave plates produces a retardance which is varied by rotation of said rotatable optic axis; and wherein the polarization of said incoming light may be oriented at any angle with respect to the optic axis of said first quarter-wave plate, except for linearly polarized light oriented at ±
45°
. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A variable retarder of linearly polarized light comprising:
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a first half-wave plate comprising a first planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and first and second quarter-wave plates positioned in series with and on either side of said half-wave plate, the optic axes of said quarter-wave plates oriented parallel or perpendicular to each other; wherein the combination of said half-wave plate with said quarter-wave plates produces a retardance which is varied by rotation of said rotatable optic axis; and wherein the polarization of said linearly polarized light is oriented at ±
45°
with respect to the optic axis of said first quarter-wave plate. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A reflection-mode variable retarder of elliptically polarized light comprising:
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a quarter-wave plate comprising a planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; a passive quarter-wave plate positioned on a first side of said liquid crystal cell; and reflective means, positioned on the second side of said liquid crystal cell, for reflecting light back through said liquid crystal cell and back through said passive quarter-wave plate; wherein the combination of said half-wave plate with said quarter-wave plate and said reflective means produces a retardance which is varied by rotation of said rotatable optic axis. - View Dependent Claims (22, 23, 24)
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25. An etalon modulator of elliptically polarized light comprising:
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front reflective means and back reflective means for providing an optical resonance cavity, and for coupling the elliptically polarized light into said resonance cavity through said front reflective means; and a variable retarder positioned within said cavity, said variable retarder comprising; a half-wave plate comprising a planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and first and second quarter-wave plates positioned in series with and on either side of said half-wave plate, the optic axes of said quarter-wave plates oriented parallel or perpendicular to each other; wherein the combination of said half-wave plate with said quarter-wave plates produces a retardance which is varied by rotation of said rotatable optic axis. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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54. A reflection-mode etalon modulator of elliptically polarized light comprising:
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front reflective means and back reflective means for providing an optical resonance cavity, and for coupling the elliptically polarized light into said resonance cavity through said front reflective means; and a variable retarder positioned within said cavity, said variable retarder comprising; a quarter-wave plate comprising a planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and a passive quarter-wave plate positioned between said liquid crystal cell and said front reflective means; wherein the combination of said half-wave plate with said quarter-wave plate and said back reflective means produces a retardance which is varied by rotation of said rotatable optic axis. - View Dependent Claims (55, 56, 57, 58, 59, 60, 61, 62, 63)
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64. A multiple pixel modulator comprising an array of etalon modulators, each etalon modulator comprising:
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front reflective means and back reflective means for providing an optical resonance cavity, and for coupling the elliptically polarized light into said resonance cavity through said front reflective means; and a variable retarder positioned within said cavity, said variable retarder comprising; a half-wave plate comprising a planar-aligned chiral smectic liquid crystal cell said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and first and second quarter-wave plates positioned in series with and on either side of said half-wave plate, the optic axes of said quarter-wave plates oriented parallel or perpendicular to each other; wherein the combination of said half-wave plate with said quarter-wave plates produces a retardance which is varied by rotation of said rotatable optic axis. - View Dependent Claims (65)
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66. A multiple pixel reflection-mode modulator comprising an array of reflection-mode etalon modulators, each modulator comprising:
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front reflective means and back reflective means for providing an optical resonance cavity, and for coupling the elliptically polarized light into said resonance cavity through said front reflective means; and a variable retarder positioned within said cavity, said variable retarder comprising; a quarter-wave plate comprising a planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and a passive quarter-wave plate positioned between said liquid crystal cell and said front reflective means; wherein the combination of said half-wave plate with said quarter-wave plate and said back reflective means produces a retardance which is varied by rotation of said rotatable optic axis. - View Dependent Claims (67)
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68. A multipixel phase modulator for light comprising an array of variable retarders, each variable retarder comprising:
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a half-wave plate comprising a planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and first and second quarter-wave plates positioned in series with and on either side of said half-wave plate, the optic axes of said quarter-wave plates oriented parallel or perpendicular to each other; wherein the combination of said half-wave plate with said quarter-wave plates produces a retardance which is varied by rotation of said rotatable optic axis. - View Dependent Claims (69)
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70. A variable retarder for light comprising:
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a half-wave plate comprising a planar-aligned chiral smectic liquid crystal cell, said cell having a rotatable optic axis; means for applying an electric field across said liquid crystal cell to rotate said optic axis; and first and second circular polarizing means for circularly polarizing light, positioned in series with and on either side of said half-wave plate, such that said first circular polarizing means is positioned to receive incoming light and couple said light with said half-wave plate, said half-wave plate is positioned to couple said light with said second circular polarizing means; wherein the combination of said half-wave plate with said first and second circular polarizing means produces a retardance which is varied by rotation of said rotatable optic axis. - View Dependent Claims (71, 72, 73, 74)
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Specification