Optical implementation of image encryption using random phase mask and speckle-free phase Fresnel hologram
Luiz Gonc¸alves Neto, Yunlong Sheng · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1997
Optical random phase masks have been proposed for security applications and image encryption. A speckle noise problem caused by the random phase mask over the reconstructed image was analyzed in a previous work, and a system using speckle- free Fourier holograms and a phase-mostly spatial light modulator (SLM) was proposed. In this paper we propose a method for the optical implementation of image encryption using a speckle-free phase Fresnel hologram and a phase- mostly spatial light modulator. A speckle-free Fresnel information. Since this approach could be implemented using a reduced number of lenses or no lenses, it has a potential for commercial applications.