Optical image encryption with spatially incoherent illumination.

A simple optical image encryption system with spatially incoherent illumination is proposed. Only one Fourier lens and one random phase plate are contained in this system. The original image is perturbed by a random phase-only mask located on the aperture plane. The encrypted information is the only intensity distribution that can be directly recorded by a CCD or CMOS. The decryption procedure can be performed digitally and the random phase distribution works as the decryption key. Numerical simulations and experimental results demonstrate the validity of the proposed method.