Paper
7 April 2000 Guardian substrate as an optical medium for security devices
Bruce A. Hardwick, Ana Ghioghiu
Author Affiliations +
Abstract
Guardian substrate is a coated polymer film that has demonstrated its suitability as a substrate for variety of printed security documents. Guardian consists of a transparent flexible polymer core layer that is coated on both sides with an opacifying coating that can be printed on using conventional printing techniques. Probably the most evolutionary feature of this substrate architecture is that is provides the facility to create areas on a document that are either transparent or semi-transparent, depending on how the coating is applied. Now for the first time documents can be secured using devices that rely on transmission through a medium with high optical clarity. Guardian substrate provides the flexibility of varying the degree of opacity to suit the device being employed. This paper discusses the benefits of this important capability, using a number of new and adapted devices to demonstrate the potential of this new platform.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bruce A. Hardwick and Ana Ghioghiu "Guardian substrate as an optical medium for security devices", Proc. SPIE 3973, Optical Security and Counterfeit Deterrence Techniques III, (7 April 2000); https://doi.org/10.1117/12.382185
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CITATIONS
Cited by 1 scholarly publication and 16 patents.
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KEYWORDS
Polymers

Image transmission

Printing

Diffractive optical elements

Coating

Optical properties

Security printing

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