Wavelets shrinkage is the most illustrative of wavelets transform for speckle noise reduction. We aim to study the performance of a monogenic wavelet transform to reduce the speckle noise in digital speckle pattern interferometric fringes. The proposed method is implemented on simulated and experimental speckle fringe patterns and its performance is appraised on the basis of peak signal-to-noise ratio (PSNR) and quality index (Q). The ability to reduce the speckle noise by the proposed method is compared with other classical speckle denoising methods. The obtained results corroborate the effectiveness of the proposed method for speckle noise reduction in speckle fringes in terms of PSNR and Q. It is also observed that the method provides better qualitative and quantitative results. Furthermore, the proposed method preserves the edge information of the speckle fringes, a feature that is quantified by the edge preservation index.

A bone's fracture could be produced by an excessive, repetitive, or sudden load. A regular medical practice to heal it is to fix it in two possible ways: external immobilization, using a ferule, or an internal fixation, using a prosthetic device commonly attached to the bone by means of surgical screws. The bone's volume loss due to this drilling modifies its structure either in the presence or absence of a fracture. To observe the bone's surface behavior caused by the drilling effects, a digital holographic interferometer is used to analyze the displacement surface's variations in nonfractured post-mortem porcine femoral bones. Several nondrilled post-mortem bones are compressed and compared to a set of post-mortem bones with a different number of cortical drillings. During each compression test, a series of digital interferometric holograms were recorded using a high-speed CMOS camera. The results are presented as pseudo 3D mesh displacement maps for comparisons in the physiological range of load (30 and 50 lbs) and beyond (100, 200, and 400 lbs). The high resolution of the optical phase gives a better understanding about the bone's microstructural modifications. Finally, a relationship between compression load and bone volume loss due to the drilling was observed. The results prove that digital holographic interferometry is a viable technique to study the conditions that avoid the surgical screw from loosening in medical procedures of this kind.

In the current work, irregular morphology of Staphylococcus aureus bacteria has been visualized by phase retrieval employing off-axis electron holography (EH) and 3D reconstruction electron tomography using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Bacteria interacting with gold nanoparticles (AuNP) acquired a shrunken or irregular shape due to air dehydration processing. STEM imaging shows the attachment of AuNP on the surface of cells and suggests an irregular 3D morphology of the specimen. The phase reconstruction demonstrates that off-axis electron holography can reveal with a single hologram the morphology of the specimen and the distribution of the functionalized AuNPs. In addition, EH reduces significantly the acquisition time and the cumulative radiation damage (in three orders of magnitude) over biological samples in comparison with multiple tilted electron expositions intrinsic to electron tomography, as well as the processing time and the reconstruction artifacts that may arise during tomogram reconstruction.

A Faraday fiber-optic current sensor was employed to measure the tokamak plasma current. In order to decrease the influence of mechanical perturbations on the sensor sensitivity, a two-pass optical scheme with a variable Faraday mirror at the fiber end is proposed. A decrease, by two orders of magnitude, in the influence of the linear birefringence produced by an external piezoceramic fiber modulator was experimentally observed.

A technique based on the electrical resistance change of a network of carbon nanotubes within a polymer composite was implemented to assess damage caused by low-velocity impact in multiscale hierarchical composites. The influence of the electrode configuration in 100 mm x 100 mm x 1.7 mm plates is addressed. Three electrode configurations are evaluated, namely, a grid on the impacted surface, a grid on the opposite (non-impacted) surface, and through the thickness of the plate. Upon impact, matrix cracking, delamination, and fiber rupture cause disruption and redistribution of the electrical network of carbon nanotubes, whose electrical resistance changes can be correlated with such damage. It is found that the non-impacted surface exhibits a higher fractional change of electrical resistance and hence higher sensitivity to damage. The results obtained using the electrical technique showed a good correlation with damage detected by independent measurements by digital holographic interferometry and ultrasonic inspections.