Optically variable devices for use on bank notes (Proceedings Paper)

The security of bank notes against counterfeiting can be improved by the incorporation of optically variable devices (OVDs), which change their appearance when the note is viewed in different directions. Three types of OVD; holograms, multiple diffraction gratings, and thin film interference filters will be compared in relation to the special requirements unique to bank notes; security, visibility and durability. The Bank of Canada has recently issued $50 bank notes bearing a five-layer thin film interf

DOI: 10.1117/12.17908
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