Liquid crystal achromatic compound retarder
First Claim
1. A liquid crystal achromatic compound retarder, comprising:
- a first passive retarder having retardance Γ
10 at a design wavelength, and orientation α
1 ; and
a second passive retarder having retardance Γ
10 at said design wavelength, and orientation α
1 ; and
a liquid crystal retarder unit, positioned between said first and second retarders, said retarder unit having composite retardance π
at said design wavelength and having composite orientation electronically switchable between α
2, in a first state, and α
2 '"'"', in a second state;
wherein α
1 and α
2 are such that said compound retarder is achromatic in said first state.
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Abstract
This invention provides achromatic liquid crystal compound retarders, achromatic polarization switches, and achromatic shutters using the liquid crystal compound retarders. It further provides achromatic variable retardance smectic liquid crystal retarders. The compound retarder of this invention comprises a central liquid crystal retarder unit and two external passive retarders positioned in series with and on either side of the liquid crystal retarder unit. The liquid crystal retarder unit comprises either (1) a rotatable smectic liquid crystal half-wave retarder or (2) first and second liquid crystal variable retarders having retardance switchable between zero and half-wave. The external passive retarders are equal in retardance and orientation to each other. Design equations determine the retardance of the external elements and their orientation relative to the central retarder to obtain a particular achromatic retardance for the compound structure.
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Citations
84 Claims
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1. A liquid crystal achromatic compound retarder, comprising:
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a first passive retarder having retardance Γ
10 at a design wavelength, and orientation α
1 ; anda second passive retarder having retardance Γ
10 at said design wavelength, and orientation α
1 ; anda liquid crystal retarder unit, positioned between said first and second retarders, said retarder unit having composite retardance π
at said design wavelength and having composite orientation electronically switchable between α
2, in a first state, and α
2 '"'"', in a second state;wherein α
1 and α
2 are such that said compound retarder is achromatic in said first state. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 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, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65)
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66. An achromatic shutter comprising:
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a first linear polarizer oriented at an angle θ
1 ;a second linear polarizer oriented at an angle θ
2 ;a liquid crystal retarder unit, positioned between said first and second polarizers, said retarder unit having composite retardance π
at a design wavelength and having composite orientation electronically switchable between 5π
/12 and 8π
/12 with respect to θ
1 ;a first retarder, positioned between said first polarizer and said liquid crystal retarder unit, having retardance π
at said design wavelength and orientation π
/12 with respect to θ
1 ; anda second retarder, positioned between said second polarizer and said liquid crystal retarder unit, having retardance π
at said design wavelength and orientation π
/12 with respect to θ
1. - View Dependent Claims (67, 68, 69, 70, 71, 72, 73, 74)
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75. A reflection-mode liquid crystal achromatic compound retarder, comprising:
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a first passive retarder having retardance Γ
10 at a design wavelength and orientation α
1 ;a reflector; and a liquid crystal retarder unit, positioned between said first retarder and said reflector, said retarder unit having composite retardance π
/2 at said design wavelength and having composite orientation electronically switchable between α
2, in a first state, and α
2 '"'"', in a second state;wherein α
1 and α
2 are such that said compound retarder is achromatic in said first state. - View Dependent Claims (76, 77, 78, 79, 80, 81, 82, 83, 84)
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Specification