US Patent 7252222 Embedded optical signatures in documents

A method of embedding an optical signature in a document and document produced therefrom. The optical signature is an optical pattern generated from a known value, such as a mathematical, geometric, trigonometric, size, phase, and the like, and the same value can be generated from examination of a document having the embedded optical pattern. The document can be validated, authenticated, or the determination of a valid copy of an original document with the embedded optical signature made through comparison of the known value and the value generated from the optical pattern on the document. The optical pattern can also be generated from other identification codes on the document.