Digital watermarking of retrieved phase maps

Abstract

A technique for digital watermarking of host object wavefronts reconstructed via a multiple-plane phase retrieval method is demonstrated experimentally. The watermark signal is encrypted using double random-phase masks and then scaled before being superposed onto the axially-displaced object intensity measurements. The host wavefront is reconstructed with imperceptible watermarks. The watermark is successfully extracted using a modified phase retrieval algorithm and the correct phase masks and distances, demonstrating the effectiveness of our technique.