Split-element liquid crystal tunable optical filter
First Claim
1. A liquid crystal split-element optical filter comprising:
- a first polarizer;
a second polarizer oriented parallel or perpendicular to said first polarizer;
a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer;
a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; and
a second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer;
wherein at least one of said retarder units comprises a liquid crystal retarder, the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function, andthe notch transmission function comprises a color transmission spectrum that is tunable between three primary colors.
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Accused Products
Abstract
This invention provides split-element liquid crystal polarization interference filters in wide-field, bandpass, cut-on, cut-off and notch filter embodiments. The split-element filters of this invention comprise a polarization interference stage defined by a pair of polarizers. Disposed within the stage are a center retarder, and first and a second split-element retarder, the split-element retarders having equal retardances and positioned in series with and on either side of the center retarder. The retarders can be liquid crystal variable retarders or can be fixed retarders used in combination with liquid crystal retarders. Double split-element filters in passive and tunable embodiments are provided comprising, within a polarization interference stage, a center retarder, an inside pair of split-element retarders and an outside pair of split-element retarders.
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Citations
63 Claims
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1. A liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer;wherein at least one of said retarder units comprises a liquid crystal retarder, the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function, and the notch transmission function comprises a color transmission spectrum that is tunable between three primary colors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function, said center retarder is a fixed center retarder and said center retarder unit further comprises a liquid crystal rotatable retarder having a first orientation perpendicular to said fixed center retarder and a second orientation parallel to said fixed center retarder. - View Dependent Claims (20, 21)
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22. A liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a fixed center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first fixed split-element retarder oriented at ±
π
/4 with respect to said first polarizer and a first liquid crystal rotatable retarder; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function. - View Dependent Claims (23, 24, 25, 26)
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27. A liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function, said center retarder is a fixed center retarder and said center retarder unit further comprises a first passive quarter-wave retarder oriented at ±
π
/4 to said first polarizer, a second passive quarter-wave retarder oriented parallel or perpendicular to said first passive quarter-wave retarder, and a liquid crystal rotatable retarder positioned between said first and second passive quarter-wave retarders, said first liquid crystal rotatable retarder having a half-wave retardance and having a continuously rotatable optic axis. - View Dependent Claims (28, 29)
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30. A liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function, said center retarder is a fixed center retarder, said first split-element retarder is a first fixed split-element retarder and said first split-element retarder unit further comprises a first passive quarter-wave retarder, positioned between said first polarizer and said first fixed split-element retarder, with optic axis oriented parallel or perpendicular to said first polarizer, and a first liquid crystal rotatable retarder positioned between said first polarizer and said first passive quarter-wave retarder, said first liquid crystal retarder having a half-wave retardance and having a continuously rotatable optic axis. - View Dependent Claims (31, 32, 33)
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34. A liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein the center retarder is a liquid crystal variable retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function. - View Dependent Claims (35, 36)
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37. A liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer;a second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer; andmeans for optically addressing the liquid crystal split-element optical filter, wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function. - View Dependent Claims (38)
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39. A multiple-pixel array comprising a plurality of liquid crystal split-element optical filters, each of the liquid crystal split-element optical filters comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function. - View Dependent Claims (40)
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41. A multi-spectral imaging device utilizing a liquid crystal split-element optical filter, the liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function. - View Dependent Claims (42)
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43. A color display utilizing a liquid crystal split-element optical filter, the liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function.
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44. A red-green-blue filter utilizing a liquid crystal split-element optical filter, the liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function.
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45. A multiple stage filter comprising first and second stages positioned in series, said first stage comprising a liquid crystal split-element optical filter, the liquid crystal split-element optical filter comprising:
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a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function; and said second stage comprising a polarizer and a retarder. - View Dependent Claims (46)
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47. A method of providing red, green and blue filtering comprising the steps of:
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providing a liquid crystal split-element optical filter, the liquid crystal split-element optical filter comprising; a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function; and tuning said filter with said liquid crystal retarder.
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48. A method of providing a multiple-pixel array of red, green and blue filtering comprising the steps of:
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providing a plurality of liquid crystal split-element optical filters, each of the liquid crystal split-element optical filters comprising; a first polarizer; a second polarizer oriented parallel or perpendicular to said first polarizer; a center retarder unit positioned between said first and second polarizers, and comprising a center retarder oriented parallel or perpendicular to said first polarizer; a first split-element retarder unit, positioned between said first polarizer and said center retarder unit, and comprising a first split-element retarder oriented at ±
π
/4 with respect to said first polarizer; anda second split-element retarder unit, positioned between said center retarder unit and said second polarizer and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientation and/or the retardances of the first and second polarizers and the retarder units are such that the filter provides a notch transmission function; and tuning said filters with said liquid crystal retarders.
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49. A multiple-pixel array comprising a plurality of reflection-mode split-element filters, each of the plurality of reflection-mode split-element filters comprising:
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a polarizer; a reflector; a center retarder unit positioned between said polarizer and said reflector, and comprising and center retarder oriented parallel or perpendicular to said polarizer; and a split-element retarder unit positioned between said polarizer and said center retarder unit and comprising a split-element retarder oriented at ±
π
/4 with respect to said polarizer,wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientations and/or the retardances of the polarizer and the retarder units are such that the filter provides a notch transmission function. - View Dependent Claims (50)
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51. A liquid crystal split-element optical filter comprising:
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a first polarizer; a first split-element retarder unit comprising a first split-element retarder, oriented at ±
π
/4 with respect to said first polarizer;a second split-element retarder unit, positioned between said first polarizer and said first split-element retarder unit, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer; anda center retarder unit positioned between said first and second split-element retarder units and comprising a fixed center retarder oriented parallel or perpendicular to said first polarizer, wherein at least one of said retarder units comprises a liquid crystal retarder, the orientations and/or the retardances of the first polarizer and the retarder units are such that input light is transformed into output light which includes at least a portion having a notch spectrum with a first polarization, said first split-element retarder is a first fixed split-element retarder and said first split-element retarder unit further comprises a first liquid crystal rotatable retarder. - View Dependent Claims (52, 53, 54)
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55. A liquid crystal split-element optical filter comprising:
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a first polarizer; a first split-element retarder unit comprising a first split-element retarder, oriented at ±
π
/4 with respect to said first polarizer;a second split-element retarder unit, positioned between said first polarizer and said first split-element retarder unit, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer; anda center retarder unit positioned between said first and second split-element retarder units and comprising a fixed center retarder oriented parallel or perpendicular to said first polarizer, wherein the orientations and/or the retardances of the first polarizer and the retarder units are such that input light is transformed into output light which includes at least a portion having a notch spectrum with a first polarization, said second split-element retarder is a fixed split-element retarder and said second split-element retarder unit further comprises a first liquid crystal rotatable retarder. - View Dependent Claims (56, 57)
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58. A multiple-pixel array comprising a plurality of liquid crystal split-element optical filters, each of the liquid crystal split-element optical filters comprising:
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a first polarizer; a first split-element retarder unit comprising a first split-element retarder, oriented at ±
π
/4 with respect to said first polarizer;a second split-element retarder unit, positioned between said first polarizer and said first split-element retarder unit, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer; anda center retarder unit positioned between said first and second split-element retarder units and comprising a center retarder oriented parallel or perpendicular to said first polarizer; wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientations and/or the retardances of the first polarizer and the retarder units are such that input light is transformed into output light which includes at least a portion having a notch spectrum with a first polarization. - View Dependent Claims (59)
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60. A red-green-blue filter utilizing a liquid crystal split-element optical filter, the liquid crystal split-element optical filter comprising:
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a first polarizer; a first split-element retarder unit comprising a first split-element retarder, oriented at ±
π
/4 with respect to said first polarizer;a second split-element retarder unit, positioned between said first polarizer and said first split-element retarder unit, and comprising a second split-element retarder of equal retardance to said first split-element retarder and oriented at ±
π
/4 with respect to said first polarizer; anda center retarder unit positioned between said first and second split-element retarder units and comprising a center retarder oriented parallel or perpendicular to said first polarizer, wherein at least one of said retarder units comprises a liquid crystal retarder, and the orientations and/or the retardances of the first polarizer and the retarder units are such that input light is transformed into output light which includes at least a portion having a notch spectrum with a first polarization.
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61. A split-element optical filter, comprising:
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a first polarizer; a second polarizer; a center retarder unit positioned between the first and second polarizers, and comprising a center retarder; a first split-element retarder unit, positioned between the first polarizer and the center retarder unit, and comprising a first split-element retarder; and a second split-element retarder unit, positioned between the center retarder unit and the second polarizer, and comprising a second split-element retarder of equal retardance to the first split-element retarder, wherein at least one of the retarder units comprises a liquid crystal retarder, and the orientations and/or the retardances of the polarizers and the retarder units are such that input light is transformed into output light which includes at least a portion having a notch transmission spectrum, and the notch transmission spectrum comprises a color transmission spectrum that is tunable between three primary colors. - View Dependent Claims (62, 63)
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Specification