  An optical security element containing an area of random rough relief is
proposed. It combines the low cost of mass replication inherent in traditional
security holograms with the impossibility of holographic copying, when the wave
restored by the hologram is rewritten as a copy of this hologram. The proposed
optical element is also protected from contact and photographic copying.
Laboratory samples of optical elements were obtained by taking replicas of a
rough surface. Identification of the authenticity of optical elements was
demonstrated by calculating the cross-correlation of speckle patterns produced
by coherent light scattered off different replicas. It is assumed that the
proposed security elements can be mass-produced on standard equipment for
embossing security holograms.
