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Comparison reader for holographic identification cards

  • US 4,131,337 A
  • Filed: 02/16/1977
  • Issued: 12/26/1978
  • Est. Priority Date: 02/18/1976
  • Status: Expired due to Term
First Claim
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1. A device for verifying an identification element having visible indicia thereon and on an adjacent portion thereof having a transmission hologram of said visible indicia as originally placed on the identification element, said device comprising:

  • (a) means for illumination of both said hologram and said visible indicia from the same side of said identification element;

    (b) means, including a generally planar surface, for displaying an optically produced image on said surface;

    (c) means, associated with said image displaying means, for producing an optical image of the visible indicia on the identification element;

    (d) means associated with said image displaying means, for producing a reconstructed image of the hologram on the identification element;

    (e) means for projecting said optical image and said reconstructed holographic image, in superimposed register, upon said planar surface;

    wherein said optical image producing means and said reconstructed holographic image producing means comprise a laser as a common source of radiation for each; and

    wherein said optical image projecting means comprises means including a beam attenuator for optically directing a beam from said laser which has passed through said hologram as a laser light of zero order diffraction upon the visible indicia on the identification element and for adjusting the intensity of said laser light of zero order of diffraction for equalizing the intensity of the optical image to the intensity of the laser radiation of the first order of diffraction forming the reconstructed holographic image on said planar surface.

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