Zu-jie Peng

Digital holographic reconstruction of large objects using a convolution approach and adjustable magnification

We present a numerical method for reconstructing large objects using a convolution method with an adjustable magnification. The method is based on the image locations and magnification relations of holography when the illuminating beam is a spherical wavefront. A modified version of the angular spectrum transfer function is proposed that allows the filtering in the spatial frequency spectrum. Experimental results confirm the suitability of the proposed method.

Spatial bandwidth extended reconstruction for digital color Fresnel holograms

This paper presents a reconstruction algorithm based on the convolution formula of diffraction which uses the Fresnel impulse response of free space propagation. The bandwidth of the reconstructing convolution kernel is extended to the one of the object in order to allow the direct reconstruction of objects with size quite larger than the recording area. The spatial bandwidth extension is made possible by the use of a numerical spherical wave as a virtual reconstructing wave, thus modifying the virtual reconstruction distance and increasing the kernel bandwidth. Experimental results confirm the suitability of the proposed method in the case of the simultaneous recording of two-color digital holograms by using a spatial color multiplexing scheme.

Digital holographic reconstruction of a local object field using an adjustable magnification

In the research of digital holography, this paper presents a numerical method using an adjustable magnification for local object field reconstruction together with experiment verification. The method first designs a spherical wave according to the given magnification to illuminate the digital hologram, then through a Fourier transform of diffraction, it calculates the reconstructed image plane. Afterward, a filtering window is set in the image plane to extract the image of the local object field, and then the object field reached hologram plane is formed using diffractions inverse operation. Finally, the object field is reconstructed through diffractions angular spectrum theory.

A simple and efficient algorithm to reconstruct digital color holograms

This paper presents a reconstruction algorithm based on an intermediate digital hologram which leads to the reconstruction of the image of the object with a controlled sampling pitch and number of pixels. The final image is obtained by calculating the diffraction from the intermediate hologram plane to the image plane using the convolution approach. Experimental results confirm the suitability of the proposed method. The calculation time is slightly better than the other similar approaches. Application in digital color holographic imaging shows that the proposed algorithm provides full color images of colored objects.

Digital color holographic reconstruction based on a virtual digital hologram

This paper presents a reconstruction algorithm based on an intermediate virtual digital hologram that can reconstruct color images with a controlled sampling pitch and pixel number. Experimental results confirm the suitability of the proposed method.

Speckle amplitude and phase recovering with bandwidth-extended digital holographic algorithms

New double FFT convolution algorithms based on the use of spatial spectrum scanning or numerical spherical reconstruction wave allow the full complex amplitude of large objects to be reconstructed. Experimental results in color holography and contact less metrology validate the proposed methods.

Recovering of Complex Amplitude by Use of Bandwidth-Adapted Double FFT Algorithms

Double FFT convolution algorithms based on the use of spectrum scanning and spherical reconstruction wave allow complex amplitude of large objects to be reconstructed. Experimental results in color holography illustrate the advantages of the method.

A sample test on the tilt angle of object light illumination in the digital holographic 3D surface shape detection

This paper discussed the measurement error of digital holographic 3D surface shape caused by imprecise measurement of the incident angle and the tilt angle of object light illumination in theory. The result showed that the error caused by the tilt angle is much greater than the incident angle. Then a method to accurately calculate the object lights tilt angle by detecting the interference field of reference plane is proposed based on the above discussion. Finally, the feasibility of the method is proved through a 3D surface shape detection experiment.