Abstract

Simple rainbow holograms and computer generated holograms are widely used as security elements for credit cards, ID cards official documents etc. The security of these holograms is based on the technological difficulty of their recording and their physical attachment to the document to be protected. Bayer Innovation and Optilink developed a rewritable Security Memory Card system for high-density and security data storage. The polarization holographic data storage ⁽¹⁾ provides analog encryption scheme offered an inherent copy protection mechanism. The entropy of the user data is minimized by applying a digital encryption scheme first. Using sparse modulation coding the user data is converted 2D page and fed into the system by a spatial light modulator (data SLM) illuminated with laser beam. The hologram plane is in the Fourier domain with respect to the data SLM. Encryption is accomplished via the phase code (using phase spatial light modulator) applied to the reference wave that is imaged onto the hologram plane. Due to the distributed nature of the holographic storage, it is not possible to change a part of the information stored in a hologram, since it would destroy all other parts too.

© 2007 IEEE