Correlation System for Security Validation and Verification using an Encoded Phase Mask

Verification technologies are needed to confirm the identify of perso nnel and to validate the authenticity of manufactured products. Rapid advances in computers, printers, scanners, and copiers have made it increasingly simple to reproduce security emblems traditionally used for verification and authentication. Even holograms, once considered impenetrable, are now routinely counterfeited using techniques such as contact copying. To circumvent the effectiveness of intensity sensitive devices to copy traditional security emblems, the use of complex phase patterns has been proposed. An ID card is produced by bonding a phase mask to some primary identification pattern such as a fingerprint. A nonlinear joint transform correlator is then used to match the ID card to an identical phase mask that is part of an automated reader. Such a phase encoded ID card could, however, be copied using interferometric techniques. To avoid this, we propose the use of an innovative holographic techniques, developed at MetroLaser, to create an ID card that is an inseparable combination of the phase mask and another complex wave front, unknown to a potential counterfeiter. The two patterns on the card are deconvolved using a "Key" hologram that is of the part reader, resulting in a nearly ideal security system.