Fast double-phase retrieval in Fresnel domain using modified Gerchberg-Saxton algorithm for lensless optical security systems

Abstract

A novel fast double-phase retrieval algorithm for lensless optical security systems based on the Fresnel domain is presented in this paper. Two phase-only masks are efficiently determined by using a modified Gerchberg-Saxton algorithm, in which two cascaded Fresnel transforms are replaced by one Fourier transform with compensations to reduce the consumed computations. Simulation results show that the proposed algorithm substantially speeds up the iterative process, while keeping the reconstructed image highly correlated with the original one.

Optical encryption using multiple intensity samplings in the axial domain

“…In this case, some noniterative retrieval strategies, such as transport-of-intensity equation [48], could be further investigated and applied for extracting the plaintext during image decryption. (5) The principle developed in this study is different from previous works [49][50][51][52], since multiple diffraction intensity recordings are obtained through axial translation of a CCD camera. The optical security system is effectively simplified compared with conventional holographic setups [49].…”

“…The optical security system is effectively simplified compared with conventional holographic setups [49]. In addition, phase retrieval algorithm is developed as a means to extract the plaintext during image decryption rather than for embedding the input image into phase-only masks [50][51][52].…”

Multiple-image encryption based on position multiplexing in Fresnel transform domain

“…In addition, a lensless optical system based on the FrT could be constructed accordingly [10] to be advantageous of compactness and simplicity. Besides, the increasing of the multiple-image multiplexing encryption security is also achieved in this study.…”

“…This method was modified by Li et al [8] to encrypt the image into a single POM in the input plane for the sake of convenient arrangement in applications, and by Chang et al [9] into two POMs in both planes for higher recovered quality and security. In our previous study [11], a novel method of position multiplexing for the multiple-image encryption based on the modified Gerchberg-Saxton algorithm (MGSA) [10] is proposed to solve the above problems. In this paper, we propose a new system architecture in which one more POM is utilized in the Fresnel transform domain to increase the security level.…”

Lensless multiple-image optical encryption based on improved phase retrieval algorithm

“…Hence, Situ et al [19] did not suggest encrypting multiple grayscale images in their methods since the quality of the decrypted images will be worse than that of binary images due to the obvious crosstalk [19,20]. In our previous study [21], a method of wavelength multiplexing for the multiple-image encryption based on the MGSA [22] is proposed to solve the above problems. Almost at the same period, Xiao et al [23] proposed a different method of multiple-image optical encryption based on an improved encoding approach.…”