Double random phase encryption with in-plane rotation of a modified Lohmann’s second-type system in the anamorphic fractional Fourier domain

In the last decade, investigations have been carried out on information security, based on double random phase encryption (DRPE). In DRPE, a two-dimensional image is encoded into a stationary white noise. To increase the security further, the Fourier transform is replaced with a fractional Fourier transform. Different fractional orders with random phase masks (RPMs) work as encryption keys. In the present work, image encryption is performed in the anamorphic fractional Fourier domain with a modified Lohmann's second-type (MLST) system. In-plane rotation of the MLST system adds the in-plane rotation angle as a key for encryption, in addition to the RPMs and different fractional orders in two orthogonal directions. Simulations have been carried out to substantiate the feasibility of the proposed encryption scheme. Experimental results are also given to demonstrate the optical implementation.