D.G. Abdelsalam

Bio: D.G. Abdelsalam is an academic researcher from Chonbuk National University. The author has contributed to research in topics: Interferometry & Digital holography. The author has an hindex of 9, co-authored 17 publications receiving 320 citations.

Single-shot, dual-wavelength digital holography based on polarizing separation

Abstract: We describe what we believe to be a new digital holographic configuration that can be utilized for both single-shot, dual-wavelength, off-axis geometry and imaging polarimetry. To get the feasibility of the single-shot, dual-wavelength, off-axis geometry, a sample with a nominal step height of 1.34 μm is used. Undesirable noises that strongly affect the measurement have been suppressed successfully by using a modified flat fielding method for the dual-wavelength scheme. And also, the experiment is conducted on a nanopattern sample on the basis of a single image acquisition to show the imaging polarimetry capability. The proposed scheme can provide a real-time solution for measuring three-dimensional objects having a high abrupt height difference with moderate accuracy. Furthermore, it can be used as a fast polarization imaging measurement tool.

Two-wavelength in-line phase-shifting interferometry based on polarizing separation for accurate surface profiling

Abstract: We describe a configuration that can be used for two-wavelength phase-shifting in-line interferometry based on polarizing separation. The experiment is conducted on a sample with a step height of 1.34 μm nominally. In this paper, five- and seven-phase step algorithms have been compared for their effectiveness in reducing the noise in the phase maps. The noise is further reduced by the application of the flat fielding method. The recorded interferograms are processed using seven-phase step algorithm to obtain the phase map for each wavelength separately. The independent phase maps are subtracted and a phase map for the beat-wavelength is obtained and converted to height map. The results extracted from the seven-phase step algorithm have been compared with the results extracted from the single shot off-axis geometry and the results are in agreement.

Surface Form Measurement Using Single Shot Off-axis Fizeau Interferometry

Abstract: This paper describes the surface form measurement of a spherical smooth surface by using single shot off-axis Fizeau interferometry. The demodulated phase map is obtained and unwrapped to remove the $2\pi$ ambiguity. The unwrapped phase map is converted to height and the 3D surface height of the surface object is reconstructed. The results extracted from the single shot off-axis geometry are compared with the results extracted from four-frame phase shifting in-line interferometry, and the results are in excellent agreement.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Polarization-sensitive low-coherence reflectometer for birefringence characterization and ranging

Abstract: We present a polarization-sensitive optical coherence-domain reflectometer capable of characterizing the phase retardation between orthogonal linear polarization modes at each reflection point in a birefringent sample. The device is insensitive to the rotation of the sample in the plane perpendicular to ranging. Phase measurement accuracy is ±0.86°, but the reflectometer can distinguish local variations in birefringence as small as 0.05° with a distance resolution of 10.8 μm and a dynamic range of 90 dB. Birefringence-sensitive ranging in a wave plate, an electro-optic modulator, and a calf coronary artery is demonstrated.

Single-shot, dual-wavelength digital holography based on polarizing separation

Abstract: We describe what we believe to be a new digital holographic configuration that can be utilized for both single-shot, dual-wavelength, off-axis geometry and imaging polarimetry. To get the feasibility of the single-shot, dual-wavelength, off-axis geometry, a sample with a nominal step height of 1.34 μm is used. Undesirable noises that strongly affect the measurement have been suppressed successfully by using a modified flat fielding method for the dual-wavelength scheme. And also, the experiment is conducted on a nanopattern sample on the basis of a single image acquisition to show the imaging polarimetry capability. The proposed scheme can provide a real-time solution for measuring three-dimensional objects having a high abrupt height difference with moderate accuracy. Furthermore, it can be used as a fast polarization imaging measurement tool.

Two-wavelength in-line phase-shifting interferometry based on polarizing separation for accurate surface profiling

Abstract: We describe a configuration that can be used for two-wavelength phase-shifting in-line interferometry based on polarizing separation. The experiment is conducted on a sample with a step height of 1.34 μm nominally. In this paper, five- and seven-phase step algorithms have been compared for their effectiveness in reducing the noise in the phase maps. The noise is further reduced by the application of the flat fielding method. The recorded interferograms are processed using seven-phase step algorithm to obtain the phase map for each wavelength separately. The independent phase maps are subtracted and a phase map for the beat-wavelength is obtained and converted to height map. The results extracted from the seven-phase step algorithm have been compared with the results extracted from the single shot off-axis geometry and the results are in agreement.

Single-shot parallel four-step phase shifting using on-axis Fizeau interferometry

Abstract: The purposes of the paper are threefold: (1) to show the possibility to perform parallel phase-shifting Fizeau interferometry by using a quarter waveplate with high flatness as a reference, (2) to present a comparative study between the phase-shifting algorithm and the off-axis geometry in surface microtopography measurement, and (3) to show the advantages of using the proposed common path Fizeau interferometry over the quasi-common path Michelson interferometry in terms of accuracy in measurement. The compelling advantage of the proposed parallel phase-shifting Fizeau interferometric technique is the long-term stability that leads to measuring objects with a high degree of accuracy.