Encrypting digital hologram of three-dimensional object using diffractive imaging

Abstract

In this paper, we demonstrate three-dimensional (3D) object encryption using diffractive imaging and digital holography. For this purpose, a microlens array has been fabricated using the thermal reflow method, and then its digital hologram is recorded. The hologram of the microlens is encoded based on multiple intensity samplings of the complex-amplitude wave front with axial translation of the image sensor in the fractional Fourier transform domain. Then, the function is Fresnel propagated for three different positions of the camera, and the corresponding diffraction patterns are recorded as cipher-texts. For decryption, an iterative phase retrieval algorithm is applied to extract the hologram from corresponding encrypted images. The corresponding phase profile of the microlens array is then obtained. The simulation results demonstrate that the hologram is decrypted without any stagnation problem and with a rapid convergence rate. High security of the hologram has been achieved in the proposed digital holography-based diffractive imaging scheme. The correlation coefficient, a performance measurement parameter, has been calculated to check the effectiveness of the scheme. The proposed work has been validated through both experimental and simulation results.