Authenticity checking system for identity cards - with halogram and direct image superimposed for comparison and using conventional light source with chopper

摘要

Credit cards, identity cards etc. are checked for authenticity by direct comparison of an optical image with a reconstructed hologram of the card. The optical image and the hologram reconstruction are projected superimposed on one another in the same image plane. Pref. if the light sources for the optical image and the hologram reconstruction are of different colour, one source is filtered to match its colour to the other. The brightness of the image and the hologram are also pref. matched to each other. The hologram reconstruction is pref. projected continuously and the image intermittently.