Identification system comprising a partially reflective retardation device
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United States of America Patent
Stats
-
Apr 21, 1987
Grant Date -
N/A
app pub date -
Dec 3, 1984
filing date -
Dec 3, 1984
priority date (Note) -
Expired
status (Latency Note)
Importance
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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