Multiple-image encryption based on interference principle and phase-only mask multiplexing in Fresnel transform domain

In this article, a multiple-image encryption method based on the optical interference principle and phase-only mask (POM) multiplexing is proposed. During the encryption process, each secret image is encoded into two analytically obtained POMs and one computer-generated random POM, in which no iterative computation is required. The analytically obtained POMs taken from different secret images are then synthesized by POM multiplexing and further encoded into two complex ciphertext images. The silhouette problem that exists in the earlier interference principle-based encryption approaches is totally resolved by the proposal. Both digital and optical means can be used for decryption. The crosstalk effect between the secret images will not appear in the decrypted results by using the proposed system. Numerical simulations have been given to verify the performance and feasibility of the proposal. We also discuss briefly the influence of information compression on the quality of decrypted images.