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Plane parallel optical collimating device employing a cholesteric liquid crystal

  • US 5,715,023 A
  • Filed: 04/30/1996
  • Issued: 02/03/1998
  • Est. Priority Date: 04/30/1996
  • Status: Expired due to Fees
First Claim
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1. An optical collimating apparatus for focussing an image at infinity or at a desired finite distance as viewed by an observer, the apparatus comprising:

  • a first optical singlet having a first surface and a second surface;

    a second optical singlet having a first surface and a second surface, said first surface of said first optical singlet coupled to said first surface of said second optical singlet;

    a partially reflective coating interposed between said first surface of said first optical singlet and said first surface of said second optical singlet;

    an image source for producing said image with light within at least a first wavelength band and with at least a first rotary sense of circular polarization, said image source proximate to said second surface of said first optical singlet; and

    a first cholesteric liquid crystal element proximate to said second surface of said second optical singlet, said first cholesteric liquid crystal element reflecting light of said first rotary sense of circular polarization within said first wavelength band.

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