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Split-element liquid crystal tunable optical filter

  • US 6,091,462 A
  • Filed: 06/11/1996
  • Issued: 07/18/2000
  • Est. Priority Date: 10/30/1989
  • Status: Expired due to Term
First Claim
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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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