Structured-illumination-based lensless diffractive imaging and its application to optical image encryption

In this paper, we propose a new method in the structured-illumination-based lensless diffractive imaging using variable grating pitches. When a phase grating pitch is sequentially changed, a series of diffraction patterns can be recorded by a charge-coupled device (CCD) camera. Subsequently, a phase retrieval algorithm with a rapid convergence rate is developed to recover a high-quality object from the recorded diffraction patterns. The proposed method is further applied to optical image encryption, and simulation results are presented to demonstrate validity of the proposed method.