Pietro Ferraro

Bio: Pietro Ferraro is an academic researcher from National Research Council. The author has contributed to research in topics: Digital holography & Holography. The author has an hindex of 61, co-authored 653 publications receiving 12666 citations. Previous affiliations of Pietro Ferraro include Aeritalia & Centre national de la recherche scientifique.

Interferometric Technique for Characterization of Ferroelectric Crystals Properties and Microengineering Process

Abstract: A DH technique for non-invasive real-time visualization of switching ferroeletric domains with high spatial and temporal resolution has been proposed and demonstrated in this paper. The technique provides the reconstruction of the phase shift distribution of the wavefield transmitted by the sample during poling by making use of the EO and piezoelectric effect occurring under the external voltage. The technique can be used as an accurate and high-fidelity method for monitoring the period ic poling process as an alternative to the commonly used poling current control. Further experiments are under investigation in case of photoresist patterned samples by using a microscopic configuration of the MZ interferometer.

Interferometric method for measuring the refractive index profile of optical waveguides directly written in glass substrates by femtosecond laser

Abstract: Direct waveguide writing by femtosecond lasers is rapidly becoming a promising valid alternative to standard fabrication techniques. Significant research efforts are devoted to understanding the effects of interaction of the radiation with the material and determining the key parameters in the writing process. The assessment of a reliable fabrication process depends crucially also on the availability of high resolution inspection and measurement methods. In this paper we employ digital holography (DH) in a microscope configuration as the characterization tool for measuring the refractive index profile of the waveguides. The method offers the advantages of high spatial resolution, high sensitivity and it allows to determine an absolute value of refractive index change without the need of any calibration. We report on the optical characterization of optical waveguides operating at 1.5 micron wavelength in two commercial glasses written by a stretched-cavity femtosecond Ti:sapphire oscillator. Measurements made by DH have evidenced a strong dependence of the fabrication process on the type of glass substrate.

Label-free microfluidic platform for blood analysis based on phase-contrast imaging

Abstract: A lab-on-chip platform for blood cells analysis will be presented that combine phase-contrast label-free imaging, microfluidics and artificial intelligence. Such platform will have important impact in the aerospace field quantifying the effect on the blood cells of astronauts stresses. Furthermore, smart and innovative platform for blood analysis could be the key element for innovative biomedicine and telemedicine solutions in aerospace applications.

Novel concept in electro-wettability patterning with electrodes-less configuration to activate and control Liquid Microlens Arrays on functionalized polar electric substrates

Abstract: Liquid microlens array can be obtained by using a thin layer of liquid on a functionalized LiNbO3 substrate. The array is activated and controlled by electro wetting patterning and is driven by pyroelectric effect.

Label-free coherent microscopy through blood by digital holography

Abstract: Digital Holography (DH) numerical methods have been developed to allow imaging through turbid media. DH is a wide used imaging technique as it provides non-invasive quantitative phase-contrast mapping as well as flexible numerical refocusing of samples acquired in lens-based or lensless conditions. However, a challenging issue has to be faced when the samples are immersed inside a dynamic turbid medium, as biological occluding objects out of interest provoke severe light scattering or unpredictable time-variable phase delays which scramble the object information, so that in many cases the sample is not visible at all. Here we show a simple technique, named Multi-Look Digital Holography (MLDH), able to fully recover the useful signal of the specimen of interest dipped inside the turbid liquid phase. Multiple hologram recordings are incoherently combined to synthesize the whole complex field carrying the useful information, thus revealing the hidden objects. In particular, it will be shown that both amplitude imaging and phase-contrast mapping of cells hidden behind a flow of Red Blood Cells can be obtained. Besides, qualitative comparison and quantitative evaluation show a remarkable improvement with respect to the image captured when the cells were immersed in a transparent medium. In other words, the RBCs have been demonstrated to accomplish an optical task, acting as a speckle noise de-correlation device.

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.

Fiber grating sensors

Abstract: We review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period-based grating sensors, fiber grating laser-based systems, and interferometric sensor systems based on grating reflectors.