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Proceedings Paper

Advanced optical document security elements
Author(s): Marek Škereň; Jakub Svoboda; Martin Possolt; Milan Květoň; Pavel Fiala
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Paper Abstract

ABSTRACT Synthetic diffractive structures represent an important tool in the optical document security. Their macroscopic visual behavior is based on properties of a very fine micro-structure which cannot be copied using common copying techniques. The visual effects can be easily observed by a common observer without any special inspection tools. However, when a high level of security is needed, additional features are often included based on an optical encryption of information. In this paper, a novel encryption technique is presented, which is based on utilizing the plastic holographic foil as a waveguide and special diffractive structures as coupling elements. When an in-coupling area is illuminated with a defined light beam, the light is coupled into the waveguide and travels to an out-coupling part. The encrypted information is encoded either in the shape of the out-coupling area or it can be formed from an out-coupling hologram in free space above the element. Both laser and normal white light sources can be used for reading the information. The coupling areas can be mixed with diffractive micro-structures forming visual effects and can be invisible during a normal observation of the hologram. The couplers can be realized using the technology fully compatible with the standard process for mastering and replication of the security elements. Several extensions of the described idea of waveguide cryptograms are also included. Finally, a set of real samples of the security elements is presented, which were realized using an advanced matrix laser lithography technique.

Paper Details

Date Published: 18 December 2012
PDF: 8 pages
Proc. SPIE 8697, 18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 86970M (18 December 2012); doi: 10.1117/12.2006042
Show Author Affiliations
Marek Škereň, Czech Technical Univ. in Prague (Czech Republic)
Jakub Svoboda, Czech Technical Univ. in Prague (Czech Republic)
Martin Possolt, Czech Technical Univ. in Prague (Czech Republic)
Milan Květoň, Czech Technical Univ. in Prague (Czech Republic)
Pavel Fiala, Czech Technical Univ. in Prague (Czech Republic)

Published in SPIE Proceedings Vol. 8697:
18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics
Jan Peřina Jr.; Libor Nozka; Miroslav Hrabovský; Dagmar Senderáková; Waclaw Urbańczyk; Ondrej Haderka; Libor Nožka, Editor(s)

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