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.

Investigation on microfluidic particles manipulation by holographic 3D tracking strategies

Abstract: We demonstrate a 3D holographic tracking method to investigate particles motion in a microfluidic channel while unperturbed while inducing their migration through microfluidic manipulation. Digital holography (DH) in microscopy is a full-field, label-free imaging technique able to provide quantitative phase-contrast. The employed 3D tracking method is articulated in steps. First, the displacements along the optical axis are assessed by numerical refocusing criteria. In particular, an automatic refocusing method to recover the particles axial position is implemented employing a contrast-based refocusing criterion. Then, the transverse position of the in-focus object is evaluated through quantitative phase map segmentation methods and centroid-based 2D tracking strategy. The introduction of DH is thus suggested as a powerful approach for control of particles and biological samples manipulation, as well as a possible aid to precise design and implementation of advanced lab-on-chip microfluidic devices.

On Unique Ergodicity Of Coupled AIMD Flows

Abstract: The AIMD algorithm, which underpins the Transmission Control Protocol (TCP) for transporting data packets in communication networks, is perhaps the most successful control algorithm ever deployed. Recently, its use has been extended beyond communication networks, and successful applications of the AIMD algorithm have been reported in transportation, energy, and mathematical biology. A very recent development in the use of AIMD is its application in solving large-scale optimization and distributed control problems without the need for inter-agent communication. In this context, an interesting problem arises when multiple AIMD networks that are coupled in some sense (usually through a nonlinearity). The purpose of this note is to prove that such systems in certain settings inherit the ergodic properties of individual AIMD networks. This result has important consequences for the convergence of the aforementioned optimization algorithms. The arguments in the paper also correct conceptual and technical errors in [1].

Conical microstructures made of biopolymers for guiding and delivering light

Abstract: Optical microstructures are of very high interest for delivering and or guiding optical radiation. Beyond the replacement of conventional hypodermic syringes, the use of microneedles opened the route towards portable lab on chip devices where the same microneedle could be used for drug delivery and photodynamic therapy, focusing the light thorough the needle tips. Here we propose for the first time an innovative approach for the fabrication of polymeric conical structures and the optical characterization of the light guided through a pyro-electrodrawn micro needle. A point-like thermal stimulation of a ferroelectric crystal enabled the electro-drawing of single or parallelized needles. The results reported show the possibility of tuning the geometry and the dimension of the structures produced and their use for controlling and guiding external light. The structures have been realized using a biocompatible and biodegradable polymer thus such conical structures in principle could be implantable. The conical structures have been characterized in terms of geometry, shape and emitted light profile. We report experimental results and discuss results and perspectives for exploiting them.

Infrared digital holography for 3D display

Abstract: We report on Infrared Digital Holography (IRDH) and discuss the advantages offered by this technique. Efficient recording-reconstructions of IR holograms of various objects, which differ in composition and dimensions, are shown. We demonstrate optical holographic display by means of a liquid crystal based Spatial Light Modulator (SLM), which gives the chance to get direct 3D imaging and display of the IR holograms. Finally, 3D dynamical scenes can be numerically synthesized and displayed in the visible region, using holograms of different objects.

Self-assembling of liquid crystal droplets on lithium niobate substrates driven by pyroelectric effect

Abstract: It is known that one of the major attractive feature of liquid crystals (LCs) lies in the fact that their optical properties can be modulated by electric, optical or magnetic fields. Recently, it was discovered that liquid crystal droplets, in particular conditions, can be driven in desired locations following electric field lines. The pyroelectric properties of the periodically poled lithium niobate (PPLN) crystal are exploited and PPLN crystal is used as substrate. In fact, heating and/or cooling this material, it has already been demonstrated that surface charges can appear, by pyroelectric effect, leading to very interesting phenomena. Then, being a polar LC molecule, it undergoes a force due to the existing fields, able to move the material. Results show that fragmented droplets coalesce to form bigger droplets in fixed locations, on a longer time scale. In some cases, one single drop can be observed onto each hexagonal domain. These drops behave as microlenses and the whole sample could be viewed as a dynamical optical micro-element able to switch from a diffuser state (fragmentation state) to a microlens array (coalescence state), without the need of an external voltage. Moreover, the birefringent properties of liquid crystals can make such microlenses also tunable.

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.