Cascaded Fresnel Diffractive System for Optical Image Security
级联菲涅尔衍射光学图像安全系统

The capability of encrypting and hiding the optical image was verified by the computer simulations.Some properties for application were found through theoretical analysis:additional freedom for system design is provided by the quantization of phase codes; increasing the number of diffractive-stage is able to improve the recovered quality,though the present system is more sensitive to the shifting of wavelength; the axial shifting of phase codes also brings noise signal,the longer propagation distance of which results in worse recovered quality.