Programmable optical security systems using computer-generated holography

A double random phase optical encryption system that uses a binary key code is proposed. The key code is generated as a binary computer generated hologram. The binary key code call be displayed on a binary spatial light modulator such as a ferroelectric liquid crystal display. The use of a binary spatial light modulator enables us to renew the key at high speed. A joint transform correlator based on a photorefractive crystal in the Fourier domain is used to perform shift invariant encryption and decryption. Computer simulations of the effects of using a binary encoded key code instead of a complex amplitude key code are shown. Preliminary optical experimental results are presented to demonstrate the effectiveness of the proposed system.