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Finger identification

  • US 4,053,228 A
  • Filed: 12/12/1975
  • Issued: 10/11/1977
  • Est. Priority Date: 12/12/1975
  • Status: Expired due to Term
First Claim
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1. Identification apparatus comprising:

  • a source of spatially coherent light to provide an interrogating beam,a plate transparent to said interrogating beam, said plate having first and second surfaces, said second surface being adapted to receive a fingerpress,said beam being directed to said first surface of said plate,said beam being partially reflected at said second surface of said plate when a fingerpress is applied at said second surface to provide a reflected light beam modulated with identification information,said partial reflection having a first magnitude at an optical discontinuity between said plate and the finger crests applied thereto, said partial reflection having a second magnitude substantially different from said first magnitude at an optical discontinuity between said plate and air,said beam being substantially orthogonal to the plane of said first and second surfaces to provide said reflected light beam with spatially undistorted identification information and optimized signal to d.c. ratio,said reflected light beam containing spatial frequencies down to zero to provide finger geometry information and indentification means optically coupled to said reflected light beam.

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