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Embedded optical signatures in documents

  • US 7,837,117 B2
  • Filed: 03/29/2006
  • Issued: 11/23/2010
  • Est. Priority Date: 12/19/2003
  • Status: Active Grant
First Claim
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1. A method of embedding an optical signature on a substrate, comprising the steps of:

  • embedding a first optical pattern on the substrate; and

    placing an invisible covering over at least a portion of the first optical pattern, the invisible covering being undetectable when exposed to a first type of light such that the optical pattern is fully detectable through the invisible covering when scanned with the first type of light, the invisible covering fluorescing when exposed to one or more non-visible wavelengths of a second type of light.

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