Modeling of spatial-frequency spectrum of security holograms and optoelectronic spectrum analyzer for their identification in real time

Abstract

The urgency of application of the optoelectronic analyzer for security holograms identification in real time for paper documents and plastic cards is obvious. The spatial-frequency spectrum analyzing method for security hologram is offered. The essence of the method consists in reception of the security holograms (SH) microstructure spatialfrequency spectrum (SFS), description SH SFS by means of integral, peak and combined parameters, and identification analyzed SH by the correlation recognition method by comparison of analyzed SH SFS parameters with reference SH SFS parameters. For this purpose it is enough to illuminate SH by laser or light-emitting diode (LED) radiation to construct by Fourier lens SH SFS, to register it with matrix receiver of radiation, and to process a signal in the electronic block. The mathematical model of a spatial-frequency spectrum of the SH is constructed and investigated. We will consider SH SFS in the limited sector of spatial frequencies. It is possible to describe SH SFS in terms of integral parameters, peak parameters, and their combinations. A series of such parameters is offered. Several SH identification algorithms is offered. The optical scheme of optoelectronic spectrum analyzer for identification SH is offered and experimentally investigated.