Optical implementation of image encryption based on digital holography and computer generated hologram

An experimental implement method of optical image encryption based on digital holography and computer generated hologram (CGH) is proposed in this paper. The actual object is encrypted by double random phase in the digital holography system and CGH encoding process, and after that the decryption is achieved in optical Fourier transform and a Fresnel diffraction system based on a spatial light modulator. In this method, both physical and digital images can be encrypted in optical systems. Meanwhile, besides the double random phase keys, Fresnel diffraction distance, wavelength key in digital holography systems and CGH coding parameters improve the security. Experimental results are in agreement with numerical calculations which show the feasibility and practicability of the proposed experimental method.