Shift-tolerance property of an optical double-random phase-encoding encryption system

We investigate the shift-tolerance property of the decrypting phase mask in an optical double-random phase-encoding encryption system. A simple method for improving the shift tolerance of the phase mask is proposed. We demonstrate how the robustness to data loss of the encrypted image extends the shift tolerance of the decrypting phase mask. The signal-to-noise ratio is calculated. Both a computer simulation and an experiment are presented.