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.
The detection of amplitude distribution of the conventional time average holography is realized through the
reconstructed image intensity, however, no satisfactory results can be often obtained because there are many noise
influences such as speckle noise. As there are only two values for the phase of the first kind of zero-order Bessel
function, namely 0 and μ, we can determine the amplitude distribution through the reconstructed field phase. And this
method is better than the conventional, but it takes a longer time. This paper presents a new method that through
introducing the shearing principle to vibration measurement of time average digital holograph, we can detect the
amplitude distribution rapidly by directly using the shearing interferogram to find out the phase stepping region, and this
method need no phase unwrapping operation. Simulation computation and experiment results show that the time new
method need for vibration measurement is shorter than that of reconstructed field phase, and the measurement effect is
better than that of reconstructed image intensity.
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.
Based on the traditional basic theory for the making of the phase hologram, the digital phase hologram is studied in this
paper. The experimental results demonstrated that, in the forming of digital phase type hologram, there exists a
constituent parameter that corresponds to the exposure time of the traditional phase type recorded by holographic plate.
By choosing the proper constituent parameter, the object wavefield can also be reconstructed from the digital phase
hologram. In this paper, the forming of the digital phase hologram and how to choose the constituent parameter are
presented, finally, the comparison between the digital amplitude holograpy and digital phase holography in theory
simulation under the same condition and the experiment verification are given out.
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 light's 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.