Institute Fisica Arroyo Seco

Arroyo Seco, Argentina

Institute Fisica Arroyo Seco

Arroyo Seco, Argentina
Time filter
Source Type

Manterola H.L.,CONICET | Manterola H.L.,Instituto Pladema | Vercio L.L.,CONICET | Vercio L.L.,Instituto Pladema | And 8 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017

Ultrasound is widely used as an inexpensive, real-time method for imaging vascular tissue. However, sonographs often lack automatic or semi-automatic software for measuring vascular diameter precisely, especially in low-and mid-income countries or institutions. Tools can be developed to perform this task, but they must be validated before being accepted for clinic use. For that purpose, in this work we present low-cost phantoms that resemble vascular tissue when subjected to ultrasound. Several materials are analysed and a step-by-step recipe for building a simple phantom is presented. Qualitatively, models were imaged by an ultrasound expert physician, and several characteristic are assessed. Quantitatively, a comparison between ultrasound and caliper measurements of the phantoms is presented. Finally, a discussion about the results and the recommended materials for low-cost vascular phantoms is carried out. © 2017 SPIE.

Pardini L.,CNR Institute of Neuroscience | Legnaioli S.,CNR Institute of Neuroscience | Lorenzetti G.,CNR Institute of Neuroscience | Palleschi V.,CNR Institute of Neuroscience | And 6 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2013

In this work, different theories for the determination of the electron density in Laser-Induced Breakdown Spectroscopy (LIBS) utilizing the emission lines belonging to the hydrogen Balmer series have been investigated. The plasmas were generated by a Nd:Yag laser (1064 nm) pulsed irradiation of pure hydrogen gas at a pressure of 2 · 104 Pa. Haα, Hβ, Hγ, Hδ, and Balmer lines were recorded at different delay times after the laser pulse. The plasma electron densitywas evaluated through themeasurement of the Stark broadenings and the experimental results were compared with the predictions of three theories (the Standard Theory as developed by Kepple and Griem, the Advanced Generalized Theory by Oks et al., and the method discussed by Gigosos et al.) that are commonly employed for plasma diagnostics and that describe LIBS plasmas at different levels of approximations. A simple formula for pure hydrogen plasma in thermal equilibriumwas also proposed to infer plasma electron density using the Hα line. The results obtained showed that at high hydrogen concentration, the Hα line is affected by considerable self-absorption. In this case, it is preferable to use the Hβ line for a reliable calculation of the electron density. © 2013 Elsevier B.V. All rights reserved.

Torre M.S.,Institute Fisica Arroyo Seco | Quirce A.,University of Cantabria | Valle A.,University of Cantabria | Pesquera L.,University of Cantabria
Journal of the Optical Society of America B: Optical Physics | Year: 2010

We report on a theoretical and experimental investigation of the bistable behavior of the polarization of longwavelength single-transverse mode vertical-cavity surface-emitting lasers (VCSELs) when subject to orthogonal optical injection. We have studied the bistability properties of the polarization switching that appear when changing the master laser wavelength with a fixed master laser power. Two bistable regions are found for polarization switchings appearing at short and long wavelengths. The directions of the obtained hysteresis cycles are in agreement with the experimental results. The widths of both bistable regions are also found to be similar and nearly independent of the injected power. The width of the region where polarization switching takes place is shown to increase as the injected power is increased. A good overall qualitative agreement is found between our theoretical and experimental results. © 2010 Optical Society of America.

Diaz Pace D.M.,Institute Fisica Arroyo Seco | Diaz Pace D.M.,CONICET | Gabriele N.A.,Campus Universitario | Garcimuno M.,Institute Fisica Arroyo Seco | And 5 more authors.
Spectroscopy Letters | Year: 2011

Laser-induced breakdown spectroscopy (LIBS) technique was applied for rapid analysis of major and minor elements composing geological samples including minerals, rocks, and a soil sample. The plasma was produced in air at atmospheric pressure by focusing on the targets a pulsed infrared Nd:YAG laser in open-path configuration. The emitted light in the UV-Vis was analyzed by a compact LIBS system to measure spectral emission lines of Si, Al, Fe, Ca, Na, K, Mg, C, Cu, Mn, and Ti. The experimental issues relevant for the analysis of the different samples were investigated by taking into account their peculiar features: drilling through a weathered layer, roughness and grain-size considerations, statistical averaging, and accuracy of the measurements. In this approach, the characterization of the samples was achieved by studying the relative variations of the emission intensities of each element normalized with respect to an internal standard. The present study shows the usefulness of LIBS as a tool for reliable identification of field samples. Copyright © Taylor & Francis Group, LLC.

Ekeroth R.M.A.,Institute Fisica Arroyo Seco | Ekeroth R.M.A.,National University of Central Buenos Aires | Lester M.,Institute Fisica Arroyo Seco | Lester M.,National University of Central Buenos Aires | And 4 more authors.
Plasmonics | Year: 2011

In this work, we show theoretical results of the behaviour of the extinction cross section as a function of the incident wavelength for metallic nanotubes (Nts) with a 2D core-shell structure. To calculate the optical response of the gold, silver and cooper system, an exact integral formalism is implemented. The method is based on Green's integral theorem, and it allows us to compute the electromagnetic field at any point in space. For a correct description of the constitutive parameters of the metallic shell, we introduce a corrective model for the dielectric function in terms of the shell thickness in the range 1 to 10 nm. In particular, we investigate the features of surface plasmons in metallic Nts, and in the cases of Au and Cu, the mechanisms of the interband transitions play a relevant role. In this paper, we show that a quasi-static approach is not sufficient to account the plasmon-plasmon interaction in Ag Nts. The aim of these studies is to characterize core size and shell thicknesses of the Nts by means of the surface plasmon resonance observed in the far field. © 2011 Springer Science+Business Media, LLC.

Salvide M.F.,Institute Fisica Arroyo Seco | Masoller C.,Polytechnic University of Catalonia | Torre M.S.,Institute Fisica Arroyo Seco
IEEE Journal of Quantum Electronics | Year: 2014

We study polarization switching and hysteresis in a vertical-cavity surface-emitting laser (VCSEL) subject to an orthogonal optical injection, such that the polarization of the injected light is perpendicular to that of the free-running VCSEL. We use the framework of the spin-flip model to characterize the polarization state of the VCSEL as a function of the frequency detuning. With appropriated injection conditions, the orthogonal polarization turns on and locks to the injected field. Increasing and decreasing the detuning across the two locking boundaries results either in narrow or wide hysteresis cycles, or even in irreversible switching. These results are in a good agreement with recent experimental observations. © 1965-2012 IEEE.

Albaladejo S.,Autonomous University of Madrid | Lester M.,Institute Fisica Arroyo Seco | Lester M.,CONICET | Saenz J.J.,Autonomous University of Madrid
Journal of the Optical Society of America B: Optical Physics | Year: 2011

Light transmission through a finite photonic crystal waveguide with an embedded cavity is analyzed in terms of the optical conductance (OC). Under appropriate conditions, the transmission is inhibited for any angle of incidence. The resonance condition manifests itself as a "dip" in the OC. Just at the resonance, the power flow presents strong vortices inside the cavity. © 2011 Optical Society of America.

Legnaioli S.,CNR Institute of Neuroscience | Lorenzetti G.,CNR Institute of Neuroscience | Pardini L.,CNR Institute of Neuroscience | Palleschi V.,CNR Institute of Neuroscience | And 8 more authors.
Spectrochimica Acta - Part B Atomic Spectroscopy | Year: 2012

In this paper, we discuss the application of laser-induced breakdown spectroscopy to precious metal alloys used for the control of the process of recovery and recycling of scraps and waste of industrial processes. In particular, the possibility to obtain sensitivity and trueness comparable to the current systems used in industrial environment in the quantitative determination of the elements of interest was explored. The present study demonstrates that laser-induced breakdown spectroscopy can be considered as a viable alternative to inductively coupled plasma optical emission spectrometry and X-ray fluorescence spectroscopy for the determination of recovered precious metals. The limits of detection obtained are of the order of 0.2 mg/g for all the elements considered. The maximum deviation with respect to the nominal concentrations is around 1 mg/g at concentrations around 20 mg/g (gold) corresponding to a relative error slightly higher than ± 5%. © 2012 Elsevier B.V.

Loading Institute Fisica Arroyo Seco collaborators
Loading Institute Fisica Arroyo Seco collaborators