Multiple-image encryption system using cascaded phase mask encoding and a modified Gerchberg-Saxton algorithm in gyrator domain

We present a novel method for multiple-image encryption by combining modified Gerchberg-Saxton algorithm (MGSA) with phase-only mask (POM) multiplexing in gyrator transform (GT) domains. In this proposal, the primitive images are firstly encoded into a single synthetic complex image by phase mutual encoding and MGSA based on GT. Then the complex encoded image is further converted into two computer-generated POMs by carrying out MGSA again in GT domains. The proposed scheme has not any capability limitation that is caused by crosstalk effect between multiplexing images. An optical cascaded GT architecture, in which two POM ciphertexts and decryption phase keys are displayed in the input planes of GTs, respectively, can be employed for decryption. Combined with the POMs as main keys, the transform angles and wavelength of GTs can further increase the security of this system by offering very sensitive additional keys. Moreover, one can adjust the transform angles of GT flexibly without using any axis movement. Numerical simulations have been carried out to verify the effectiveness and feasibility of the proposed method.