Optical security elements based on waveguide effects

0444540 - ÚFP 2016 RIV US eng C - Conference Paper (international conference)
Possolt, Martin - Škereň, M. - Svoboda, J.
Optical security elements based on waveguide effects.
Proceedings of SPIE Vol. 9442: Optics and Measurement Conference 2014. Vol. 9442. Bellingham: SPIE-INT SOC OPTICAL ENGINEERING, 2015 - (Kovačičinová, J.; Vít, T.), s. 944214-944214. SPIE. ISBN 978-1-62841-557-5. ISSN 0277-786X.
[Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014]
Institutional support: RVO:61389021
Keywords : diffractive security element * waveguide effect * grating coupler
Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
http://spie.org/Publications/Proceedings/Paper/10.1117/12.2175918

Optical document security represents an important field of application of analogue and synthetic diffractive structures.Most of the security elements are based on visual effects formed by diffraction on a structure with the details in the order of hundreds of nanometers.However,to improve the anti-counterfeiting properties of these structures, various types of hidden features are included within the area of the security elements.They are not visible under normal lighting but it is possible to easily reveal the hidden information under specially-defined geometry and/or type of illumination.In this paper, theory and application of a novel type of hidden diffractive security element are presented.It combines standard visual properties of synthetic holograms with waveguide effects.The hidden information is recorded using a special grating,which is not visible under normal observation geometry.The encoded image can be reconstructed only when the proper guided mode appears in a substrate.
Permanent Link: http://hdl.handle.net/11104/0247047