Image encryption based on anamorphic fractional Fourier transform and three-step phase-shifting interferometry

A new optical image encryption method based on anamorphic fractional Fourier transform (FRT) and phase-shifting interferometry (PSI) is proposed in this paper. The input two-dimensional image to be encrypted is anamorphic fractional Fourier transformed with different orders in the two orthogonal directions, respectively. Three-step PSI is applied to record the digital hologram of the data encrypted by use of double-random phase encoding technique in the FRT domain. The orders of anamorphic FRT, random phase mask in the fractional Fourier plane and the arbitrary phase shifts used for recording form the keys for decryption of the input image. The correctness and feasibility of this method are verified by computer simulations.