Laser induced fluorescence applied to diagnosis in calcareous stones

R. Ortiz, P. Ortiz, M.A. Vázquez, J.M. Martín, F. Colao, R. Fantoni

Research output: Contribution to conferencePaper

1 Citation (Scopus)

Abstract

The Laser Induced Fluorescence (LIF) technique has been already proved to be a powerful diagnostic tool for artworks. The aim of this work is to validate LIF measurements to detect the different detrimental effects of the environmental conditions on the stone materials and to discriminate among different biofilms and crust from smog or pollutants, in order to optimize the restorers’ interventions. A scanning LIF system at 266 nm excitation wavelength has been employed. The line scanning system has operated in two operating mode: reflectance and fluorescence. Reflectance measurements are made by performing a scan while the laser is off and the sample is exposed to the light emitted by a NIST traceable lamp. The result gives for each pixel of the scanned area the reflectance spectrum, from which the CIE/lab coordinates can be computed once the system is calibrated against a reference surface. The samples were placed on a holder for LIF measurements. The acquisition system was placed at than 3.5 m distance from the target and several images acquired with a spatial resolution of approximately 0.0025 m. The most relevant spectral features of crusts are identified by Principal Component analysis. Three groups of samples can be detected: a) samples with blue false color in the images, that are mainly formed by biocrust, b) samples mainly composed with crust and deposits with yellow or green colour, c) samples with no difference between faces. These classifications of samples are mainly according to the results obtained by morphometric techniques. LIF and reflectance measures seems a very powerful technique in this preliminary results, to discriminate the presence of biocrust and crusts/deposits with more sensitive that a naked-eye at 2.5 m of monuments.
Original languageEnglish
Publication statusPublished - 2014
Externally publishedYes
Event2nd International Congress on Science and Technology for the Conservation of Cultural Heritage, 2014 - Sevilla, Spain
Duration: 1 Jan 2014 → …

Conference

Conference2nd International Congress on Science and Technology for the Conservation of Cultural Heritage, 2014
CountrySpain
CitySevilla
Period1/1/14 → …

    Fingerprint

All Science Journal Classification (ASJC) codes

  • Computer Science Applications
  • Archaeology
  • Conservation

Cite this

Ortiz, R., Ortiz, P., Vázquez, M. A., Martín, J. M., Colao, F., & Fantoni, R. (2014). Laser induced fluorescence applied to diagnosis in calcareous stones. Paper presented at 2nd International Congress on Science and Technology for the Conservation of Cultural Heritage, 2014, Sevilla, Spain.