Paper
18 December 2012 Advanced optical document security elements
Marek Škereň, Jakub Svoboda, Martin Possolt, Milan Květoň, Pavel Fiala
Author Affiliations +
Proceedings Volume 8697, 18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics; 86970M (2012) https://doi.org/10.1117/12.2006042
Event: 18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 2012, Ostravice, Czech Republic
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.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Marek Škereň, Jakub Svoboda, Martin Possolt, Milan Květoň, and Pavel Fiala "Advanced optical document security elements", Proc. SPIE 8697, 18th Czech-Polish-Slovak Optical Conference on Wave and Quantum Aspects of Contemporary Optics, 86970M (18 December 2012); https://doi.org/10.1117/12.2006042
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KEYWORDS
Waveguides

Holograms

3D image reconstruction

Information security

Image encryption

Holography

Chemical elements

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