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Details

  • Nationality

    Portugal
  • Centre

    Applied Photonics
  • Contacts

    +351220402301
    miguel.s.ferreira@inesctec.pt
001
Publications

2019

Application of a novel LIBS prototype as an analytical grade tool for Li quantification in pegmatite samples

Authors
Guimaraes, D; Ferreira, MFS; Ribeiro, R; Dias, C; Lima, A; Martins, RC; Jorge, PAS;

Publication
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
A high-resolution advanced laser induced breakdown spectroscopy prototype was used to quantify lithium (Li) in lithiniferous rocks. Samples were collected from Barroso's mine (Portugal), claimed as Western Europe's largest spodumene Li discovery. 51 samples from a reverse circulation drill were collected, one for each meter interval, dried, milled, pressed into pellets and further analyzed by laser induced breakdown spectroscopy. Quantification was attempted using either linear models based on the intensity of selected Li spectral lines or advanced chemometrics methods. The latter was very successful, with correlation coefficients of 0.97 against certified laboratory results. © 2019 SPIE.

2019

Plasma control by pattern recognition in laser induced breakdown spectroscopy

Authors
Ferreira, MFS; Guimaraes, D; Jorge, PAS; Martins, RC;

Publication
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
A low-computational intensive laser control approach is proposed for implementing an embedded control system, using pattern recognition by relevant principal component analysis for laser induced breakdown spectroscopy applications. The laser energy is directly related to the resulting spectral pattern and is determined by iterations in the feature space. Results show that single shot iterations until optimum energy can be significantly reduced by pattern recognition. A performance benchmark with minerals, alloys and pellets from material collected from a drill demonstrated an average of 50% improvement, significantly reducing sample deterioration and improving measurement safety. © 2019 SPIE.

2018

The fiber connection method using a tapered silica fiber tip for microstructured polymer optical fibers

Authors
Ferreira, M; Gomes, A; Kowal, D; Statkiewicz Barabach, G; Mergo, P; Frazão, O;

Publication
Fibers

Abstract
In this work, an alternative method of coupling light into microstructured polymer fibers is presented. The solution consists in using a fiber taper fabricated with a CO2 laser. The connection is formed by inserting a tapered silica tip into the holes of a microstructured polymer fiber. This alternative method is duly characterized and the feasibility of such fiber connection to enable the polymer fiber as a displacement sensor is also demonstrated. © 2018 by the authors.

2017

Polymer and tapered silica fiber connection for polymer fiber sensor application

Authors
Ferreira, MFS; Gomes, AD; Kowal, D; Statkiewicz Barabach, G; Mergo, P; Frazao, O;

Publication
THIRD INTERNATIONAL CONFERENCE ON APPLICATIONS OF OPTICS AND PHOTONICS

Abstract
A new type of polymer and silica connection is proposed. A tapered SMF- 28 silica optical fiber tip is fabricated using a CO2 laser by focusing and stretching the fiber. The tapered silica tip is inserted in one of the holes of a microstructured polymer optical fiber using a 3D alignment system. Using a supercontinuum source, the spectrum is observed after one and after two connections. The polymer fiber is characterized in curvature while using the previous connection.

2017

Fabry-Perot cavity based on polymer FBG as refractive index sensor

Authors
Ferreira, MFS; Statkiewiez Barabach, G; Kowal, D; Mergo, P; Urbanczyk, W; Frazao, O;

Publication
OPTICS COMMUNICATIONS

Abstract
The use of a polymer fiber as a refractive index sensor is proposed. A fiber Bragg grating is inscribed near the fiber tip and the fiber is cut shorter thus creating a Fabry-Perot cavity. The reflections between the fiber Bragg grating and the fiber end-face create a Fabry-Perot interferometer. The sensor was characterized to refractive index changes at constant temperature and to temperature at constant refractive index using a fast Fourier transform analysis of the interference signal. The sensor revealed a sensitivity of-1. 94 RIU-1 with a resolution of lx10(-3)RITJ and low sensitivity to temperature, with a cross sensitivity to temperature of 3. 6x10(-4)RIU/degrees C.