Lingfeng Yu

Iterative algorithm with a constraint condition for numerical reconstruction of a three-dimensional object from its hologram.

A novel method to obtain the three-dimensional mathematical model of a transparent object from its hologram is presented. The proposed method can numerically extract the object information from the fringe pattern of the hologram. Then an iterative algorithm is used to imitate an imaging system by focusing on different layers of the object; and by operating in both the spatial domain and the frequency domain, the algorithm produces a series of two-dimensional layer images. The object is finally reconstructed layer by layer. A constraint condition should be satisfied, and the noise distribution can be rearranged in different reconstruction cycles so as to get better reconstruction quality. Numerical simulations have proved the effectiveness of the proposed method.

Numerical reconstruction of digital holograms with variable viewing angles

Here we describe a new method for numerically reconstructing an object with variable viewing angles from its hologram(s) within the Fresnel domain. The proposed algorithm can render the real image of the original object not only with different focal lengths but also with changed viewing angles. Some representative simulation results and demonstrations are presented to verify the effectiveness of the algorithm.

Multidimensional data encryption with digital holography

A new method based on the concept of virtual optics for both encryption and decryption is proposed. It analyzes the potential reasons of the limitations of our earlier work and presents some new approach to improve the original algorithm. Different methods of numerical reconstruction for data encryption are compared, the limitations caused by off-axis setups are discussed, and the resolution of the decrypted image could be flexibly adjusted, which makes it possible to decrypt the image with virtually no loss of data. Numerical experiments are performed to validate the proposed method, and sensitivities of some parameters are quantitatively analyzed and illustrated.

Parameterized multi-dimensional data encryption by digital optics

A new parameterized multi-dimensional data encryption method is presented in this paper. Several geometric and physical parameters derived out from a configuration of digital optics have been suggested as tools for designing multiple locks and keys for data encryption in hyperspace. Numerical experiments are performed to validate proposed method and parameters sensitivities are also quantitatively analyzed and illustrated with numerical simulations.

Digital audio signal encryption with a virtual optics scheme

Summary A novel approach for enciphering digital audio signal is presented in this article. The operating principle of the approach is on the basis of a virtual optics scheme whereby we apply both virtual wavelength and virtual diffraction distance in conjunction with a complex-valued random mask to design multiple-locks and multiple-keys in the course of audio data encryption and decryption. The audio signal is converted into a sound map, thus the encoded sound map can be encrypted as done for an image. Numerical experiment results show that proposed method is with high sensitivity to parameter discrepancy of virtual optical scheme. The correlation analysis of decrypted audio signal in comparison with original signal is also performed to verify the capability of presented virtual optics scheme for audio signal encryption.

Data encryption by disarranging the holographic information with rotated holograms

Summary A new method for information encryption is presented in this paper. The new encryption method takes advantage of the fact that the numerical reconstruction of digital holography is based on the information recorded on the hologram, and any slight disarrangement of the holographic information will make the numerical reconstruction failed. 3D rotation is introduced in the paper to disarrange the holographic information, and the rotation parameters could be used to design multiple locks and keys for data encryption. The sensitivity of the rotation angles is tested with the numerical experiments and the key dimension introduced by this method is roughly estimated. The results presented here show that data encryption with rotated hologram is feasible.

Numerical reconstruction of digital holography with changed viewing angles

This paper describes a method of numerical reconstruction for digital holography with changed viewing angles within the Fresnel domain. The proposed algorithm could not only reconstruct the real image of the original object with different focal lengths but also with changed viewing angles, which could be selected as any angle in space. Some representative simulations are presented to validate the proposed algorithm.

Numerical reconstruction of 3D objects with different viewing angles

This paper describes a method of numerical reconstruction for digital holography with changed viewing angles within the Fresnel domain. The proposed algorithm could not only render the real image of the original object with different focal lengths but also with changed viewing angles selected in 3D space. The numerical reconstruction can be implemented by using the Fast Fourier Transform. Some representative simulations are presented to validate the proposed algorithm.