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Proceedings Paper

Use of metameric filters for future interference security image structures
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Paper Abstract

In the present work, we describe innovative approaches and properties that can be added to the already popular thin film optically variable devices (OVD) used on banknotes. We show two practical examples of OVDs, namely (i) a pair of metameric filters offering a hidden image effect as a function of the angle of observation as well as a specific spectral property permitting automatic note readability, and (ii) multi-material filters offering a side-dependent color shift. We first describe the design approach of these new devices followed by their sensitivity to deposition errors especially in the case of the metameric filters where slight thickness variations have a significant effect on the obtained colors. The performance of prototype filters prepared by dual ion beam sputtering (DIBS) is shown.

Paper Details

Date Published: 9 February 2006
PDF: 9 pages
Proc. SPIE 6075, Optical Security and Counterfeit Deterrence Techniques VI, 60750T (9 February 2006); doi: 10.1117/12.668924
Show Author Affiliations
Bill Baloukas, École Polytechnique, Montréal (Canada)
Stéphane Larouche, École Polytechnique, Montréal (Canada)
Ludvik Martinu, École Polytechnique, Montréal (Canada)

Published in SPIE Proceedings Vol. 6075:
Optical Security and Counterfeit Deterrence Techniques VI
Rudolf L. van Renesse, Editor(s)

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