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Proceedings Paper

A polarization-sensitive diffractive optical device for document security
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Paper Abstract

Devices for document security consisting of a thin metallic film the boundaries of which are undulated with a relief of a rainbow hologram, with the lower boundary facing to a lossless medium and the upper one facing (i) to a lossless medium with the same refractive index or (ii) to a thin dielectric film with a higher refractive index, are proposed. When viewed through in collimated and monochromatic light, they exhibit unique angular variation of appearance - a marked succession of dark and bright areas if the incident beam is polarized in the plane of recording of the hologram (the s-polarization). The devices are modelled as single-film and double-film structures that are composed either of a 30 nm thick silver film, which is sandwiched between two photoresist layers, or of a 30 nm thick silver film, which is deposited on a photoresist layer, and a 60 nm thick overlay film of titanium dioxide. Sensitivity to the polarization and the unique angular variation for the s-polarization follow from theoretical calculations, assuming a sinusoidal modulation of the surface relief, and they are demonstrated experimentally by capturing intensity distributions of light transmitted through realized samples in the zero diffraction order.

Paper Details

Date Published: 25 April 2008
PDF: 8 pages
Proc. SPIE 6994, Photon Management III, 69940V (25 April 2008); doi: 10.1117/12.778998
Show Author Affiliations
Ivo Aubrecht, Police Presidium CR (Czech Republic)
Miroslav Miler, Institute of Photonics and Electronics (Czech Republic)

Published in SPIE Proceedings Vol. 6994:
Photon Management III
John T. Sheridan; Frank Wyrowski, Editor(s)

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