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9 February 2006 Optically variable threads and polarization effects
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Abstract
Based on common criteria for efficient security elements for banknotes the set-up of a state-of-the-art holographic security thread is described - as first representative of window embedded OVD. We continue with new colour-shifting OVD-threads − based on physical vapour deposition thin-film and liquid crystal technology. These three then form the family of optically variable threads following the same set of requirements for efficiency, durability, service to all authentication levels and economics. In addition to this set of OVD threads we introduce how liquid crystal based phase retarding layer can be used to install new authentication channels for the public use up-to machine authentication. Also we show the perspective how those development can be used to install similar sets of OVD families of foil elements on banknotes.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Friedrich Kretschmar, Theodor Burchard, and Manfred Heim "Optically variable threads and polarization effects", Proc. SPIE 6075, Optical Security and Counterfeit Deterrence Techniques VI, 60750Y (9 February 2006); https://doi.org/10.1117/12.656344
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