Optical image hiding using double-phase retrieval algorithm based on nonlinear cryptosystem under vortex beam illumination

We propose a novel optical image hiding method based on a double-phase retrieval algorithm (DPRA) using iterative nonlinear double random phase encoding (NDRPE) in Fresnel domain under illumination of an optical vortex (OV) beam. The NDRPE-based DPRA is initially extended from the Fourier transform into the Fresnel domain, which makes the system more flexible and more compact. The proposed method has a faster convergence speed compared to its counterparts based on the linear double random phase encoding (LDRPE). A higher level of security also has been achieved by taking an OV mode as the illumination beam. Simulation results demonstrate the feasibility and security of the proposed approach.