UPSI Digital Repository (UDRep)
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Total records found : 3 |
Simplified search suggestions : Rahmatullah Bahbibi |
1 | 2014 conference_item | Development of an off-axis digital holographic microscope for large scale measurement in fluid mechanics Tamrin K. F., Rahmatullah Bahbibi, Samuri S. M., Holographic particle image velocimetry is a promising technique to probe and characterize complex flow dynamics since it is a truly three-dimensional (3D) three-component measurement technique. The technique simply records the coherent light scattered by small seeding particles that are assumed to faithfully follow the flow and uses it to reconstruct the event afterward. Re-construction of the event is usually performed using a digital video micro-scope mounted on a 3D translation stage. The microscope records the inten-sity only which consequently results in loss of phase information. The objec-tive of this paper is to develop and apply digital holographic microscopy with the aim to recover the phase information. Digital holographic microscopy has immense potentials in microscale solid and fluid measurements as it offers the possibility of digital wavefront processing by manipulating amplitude and phase of the recorded holograms. In this paper, we have developed an off-axis digital ho..... 851 hits |
2 | 2014 conference_item | Measurement of signal-to-noise ratio (SNR) in off-axis particle holography using paraxial approximation Tamrin K. F., Rahmatullah Bahbibi, Samuri S. M., Particle image velocimetry (PIV) technique in its original form is limited to in-plane two-dimensional two-component (2D-2C) displacement and velocity measurements. Although it is possible to extract the out-of-plane component through stereoscopic viewing, the useful measurement volume remains limited to a light sheet of several millimeters thick. On the other hand, integration of holographic recording in PIV (HPIV) has finally realised whole-field, three-dimensional three-component (3D-3C) displacement and velocity measurements. In comparison to in-line particle holography, off-axis particle holography offers a relatively higher signal-to-noise ratio (SNR) although it demands long coherence and high laser energy for flow diagnostics. In-line particle holography relaxes the requirements of such a system but at the expense of image (signal) degradation due to superposition of virtual image waves, the directly transmitted reconstruction wave and the real image. On this basis, off-axis se..... 766 hits |
3 | 2014 conference_item | Astigmatism compensation in digital holographic microscopy using complex-amplitude correlation Tamrin Khairul Fikri, Rahmatullah Bahbibi, Mohamad Samuri Suzani, Digital holographic microscopy (DHM) is a promising tool for a three-dimensional imaging of microscopic particles. It offers the possibility of wavefront processing by manipulating amplitude and phase of the recorded digital holograms. With a view to compensate for aberration in the reconstructed particle images, this paper discusses a new approach of aberration compensation based on complex amplitude correlation and the use of a priori information. The approach is applied to holograms of microscopic particles flowing inside a cylindrical micro-channel recorded using an off-axis digital holographic microscope. The approach results in improvements in the image and signal qualities... 1512 hits |