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2014-10-05 - Colloque/Présentation - communication orale - Anglais - 6 page(s)

Ravet Gautier, Renoirt Jean-Michel, Lahem Driss, Debliquy Marc , Caucheteur Christophe , "Early flame detection based on fiber Bragg grating sensors" in AUBE 2014, Duisburg, Germany, 2014

  • Codes CREF : Capteurs et périphériques (DI2563), Matériaux optiques (DI1256)
  • Unités de recherche UMONS : Electromagnétisme et Télécommunications (F108), Science des Matériaux (F502)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Ingénierie des matériaux (CRIM)

Abstract(s) :

(Anglais) Abstract In this presentation we propose a novel method for early fire detection based on infrared radiation measurement thanks to an optical fibre. This solution is particularly well suited for use in large infrastructures such as parkings or tunnels. Our method makes use of fibre Bragg gratings (FBGs) photo-inscribed in the core of an optical fibre with a UV laser. FBGs are selective mirrors reflecting a narrow wavelength band centred on the so-called Bragg wavelength. This Bragg wavelength is in particular sensitive to temperature changes, allowing FBGs to serve as transducing elements for sensing various physical or chemical parameters. In this work, FBGs were coated with a sensitive layer playing the role of a black body, absorbing efficiently infrared radiation emitted by flames during a fire. By monitoring a shift in the Bragg wavelength of suitably packaged FBGs, one can measure changes in infrared radiation flux incoming on the fibre. Actual fire detection systems based on optical fibres rely on optical nonlinear effects such as Raman or Brillouin scattering. These systems only account for temperature elevation as a signature of fire. However this process is rather slow in comparison with infrared detection since convection is a slower transport mechanism than radiation. Our solution reacts after a few seconds while several minutes are required for devices based on the measurement of temperature changes. Speed of detection being of paramount importance, we propose our solution as a complement of existing fire detection precautions for large infrastructures. Indeed, beside small size, immunity to electromagnetic interferences or resistance to corrosion, optical fibres have great integration and multiplexing capabilities. First, the fibre itself is the sensors as well as the transmission medium for relevant information transport. Second FBGs sensors can be cascaded at different wavelength enabling the realization of quasi-distributed measurement systems with several kilometres range. Keywords: infrared detection, flame sensor, fiber optics, early detection, infrastructures.