Practical implementation of phase-only optical encryption system

In this paper, we present a system for the practical implementation of phase-only optical encryption. Our approach is based on the use of the generalized phase contrast technique for the readout of decrypted information contained within the phase component of an optical wavefront. The decryption is achieved by superimposing a decrypting phase key and an encrypted phase mask in the image plane of an optical system and then applying the generalized phase contrast technique to generate an intensity pattern corresponding to the original encoded information. We have constructed an experimental system in which an encrypted binary phase mask is decrypted by a binary phase key that is implemented electronically on a phase-only spatial light modulator allowing a simplified electronic alignment of the key by scrolling its position with respect to the mask.