Identification system comprising a partially reflective retardat

Details Identification system comprising a partially reflective retardat Identification system comprising a partially reflective retardat

1984-12-03

1987-04-21

Bell, Paul A.

Printed matter

Having revealable concealed information, fraud preventer or...

Utilizing electromagnetic radiation

283 87, 283904, 350397, B42D 1500

Patent

active

046591125

ABSTRACT:
There is disclosed a tamper-free identification system, such as an ID card, comprising an information-bearing substrate made of a flexible but substantially rigid material, a partial light reflector superposed over said substrate which produces a substantially nondepolarizing light reflection, and a substantially transparent 90.degree. retarder superposed over said reflector. Said identification card can be manufactured at low cost using techniques known in the art, and with the aid of a simple and inexpensive analyzer such as a linear light polarizer, fraudulent alternations of the identification card can readily be detected.

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patent: 4343851 (1982-08-01), Sheptak
patent: 4379634 (1983-04-01), Rosenthal

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