Lensless optical data embedding system using concealogram and cascaded digital Fresnel hologram

A robust lensless optical data embedding system using both the computer-generated concealogram and the digital Fresnel hologram (DFH) is proposed. The concealogram and the DFH are cascaded as the input and filter planes, respectively. When the concealogram is illuminated by a plane wave, the hidden data can be extracted at the output plane without using any lenses. The longitudinal positions of the filter and the output planes, as well as the wavelength, can be used as the secret keys to enhance system security. Furthermore, the robustness of the proposed system against noise and distortion is also demonstrated.