Recording and reproduction of holographic coded identity cards - uses black and grey areas of hologram, corresponding to those of photograph, carrying data in various planes

摘要

The holographic coded passes and identity cards are tested by the recording and reproduction. The black areas and grey stages of a hologram correspond to those of photographs, the hologram having in one or several planes different informations or data, both analog or digital. Preferably reflection holograms are used and can be reconstructed with a determining wavelength, corresponding to the recording geometry, shrinking or swelling of the film emulsion. The holograms are read with incoherent polychromatic light, using an evaluation sensor sensitised for the special wavelengths. The coded information carriers may be integrated in a mechanically coded key, the latter serving for switching-on the reconstruction light source, or the lead-out.