Proceedings Article | 15 March 1996
Proc. SPIE. 2659, Optical Security and Counterfeit Deterrence Techniques
KEYWORDS: Diffraction, Holograms, Holography, 3D image reconstruction, Digital holography, Optical properties, Stereo holograms, Volume holography, Computer security, Diffraction gratings
We consider several aspects of security properties of holographic optically variable devices that are used for document protection. Features of optically recorded rainbow holograms, stereograms, holograms with pixel structure, and volume holograms are discussed from the point of view of optics. Similar approach is used with respect to optical properties of computer generated stereograms and digital holograms with pixel structure. Optical properties which are considered include diffraction efficiency, uniformness of the recording, angular range of horizontal parallax, multiplicity of recording, spatial separation of recording planes, color visual perception, spectral range, as well as transmission and reflection properties. The second group of security properties is connected with employed technology. Technological aspects of a hot stamping foil structure, self-destructive labels, and other are considered. Security properties of holographic optically variable marks are also analyzed in terms of novelty of employed techniques, the level of scientific and technological complexity, as well as resistance to imitating.
