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.

A new 3D tracking method exploiting the capabilities of digital holography in microscopy

Abstract: A method for 3D tracking has been developed exploiting Digital Holographic Microscopy (DHM) features. In the framework of self-consistent platform for manipulation and measurement of biological specimen we use DHM for quantitative and completely label free analysis of specimen with low amplitude contrast. Tracking capability extend the potentiality of DHM allowing to monitor the motion of appropriate probes and correlate it with sample properties. Complete 3D tracking has been obtained for the probes avoiding the issue of amplitude refocusing in traditional tracking processing. Our technique belongs to the video tracking methods that, conversely from Quadrant Photo-Diode method, opens the possibility to track multiples probes. All the common used video tracking algorithms are based on the numerical analysis of amplitude images in the focus plane and the shift of the maxima in the image plane are measured after the application of an appropriate threshold. Our approach for video tracking uses different theoretical basis. A set of interferograms is recorded and the complex wavefields are managed numerically to obtain three dimensional displacements of the probes. The procedure works properly on an higher number of probes and independently from their size. This method overcomes the traditional video tracking issues as the inability to measure the axial movement and the choice of suitable threshold mask. The novel configuration allows 3D tracking of micro-particles and simultaneously can furnish Quantitative Phase-contrast maps of tracked micro-objects by interference microscopy, without changing the configuration. In this paper, we show a new concept for a compact interferometric microscope that can ensure the multifunctionality, accomplishing accurate 3D tracking and quantitative phase-contrast analysis. Experimental results are presented and discussed for in vitro cells. Through a very simple and compact optical arrangement we show how two different functionalities can be accomplished by the same optical setup, i.e. 3D tracking of micro-object and quantitative phase contrast imaging.

Adaptive transformations for color hologram display

Abstract: The advent of digital holography (whereby the interference pattern that constitutes the hologram is recorded using a digital detector array, rather than analog photographic media) has opened up new possibilities for developing spectacular 3D imaging and display systems.1, 2 Making these a reality requires capturing all the details of an object by recording three monochromatic digital holograms with different wavelengths (red, green, blue) that correspond to the primary colors of light.3, 4 These single-color holograms can then be numerically reconstructed and combined to display a fully detailed image of the object. However, achieving good-quality results requires a strategy for correctly superimposing the reconstructed hologram images,5–10 which may differ in scale or be spatially shifted relative to each other. To address this, we have recently developed a simple method based on adaptive affine transformations of holograms that allows full control over the object’s position and size within a 3D volume.11–13 This method ensures adaptive compensation of the three constituent color holograms, which are subsequently superimposed using a correlation-matching procedure. The final step is to create a synthetic hologram, incorporating information from all the different-colored holograms recorded of the same object, using the NTSC (National Television Systems Committee) coefficients. The resulting hologram can be optically reconstructed by a spatial light modulator (SLM) at a single wavelength to display the image in 3D with all its original color features. To illustrate the steps in our proposed method, we can consider the numerical reconstructions of two digital holograms of the same object, recorded at two different wavelengths, red and green. The red and green reconstructions will have Figure 1. Reconstruction of color holograms of a matryoshka doll (a), recorded with wavelengths red D 632:8nm and green D 532nm. The reconstructions of the red (b) and green (c) holograms do not perfectly coincide spatially, producing loss of detail in their superimposition (d).

3D Full morphometric assessment by holographic imaging at lab-on-chip scale for biomedical applications

Abstract: Digital holographic microscopy is a well-established technique to study biological samples in bio-microfluidics. We demonstrate a holographic imaging tool for 3D morphometric characterization of cells, that can be integrated in Lab on Chip devices.

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.