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Proceedings Paper

Real-time monitoring of volcanic emissions with a laser-based fiber spectrometer
Author(s): Alessandra S. Rocco; Gianluca Gagliardi; Livio Gianfrani; Giuseppe De Natale; Paolo De Natale
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Paper Abstract

Recent progress in telecom-based optoelectronic devices and low power laser sources has provided new powerful tools for in-situ monitoring of volcanic areas in real-time and for long periods, with unprecedented accuracy and resolution. Such techniques represent a great improvement if compared to the traditionally used "in-situ" sampling techniques such as gas chromatography and mass spectrometry which result often impractical or dangerous, and do not allow temporally continuous monitoring Optical communication diode lasers, which emit visible and IR radiation with mW power, operating on single mode at room temperature, are ideal sources to develop high sensitivity gas analysers based on absorption spectroscopy techniques. Their possible use in conjunction with fiber components is particularly advantageous in the perspective of developing networks for simultaneous monitoring of many geochemical and geophysical parameters. We report on the field tests of a novel Portable Diode Laser Spectrometer (PDLS), operating at a wavelength of 1.99μm and based on direct absorption spectroscopy, for high precision, accurate and real-time, simultaneous measurements of CO2 and H2O concentrations. We used an open-path configuration, positioning the detection bench, equipped with a a Herriott cell especially designed for measurements in hazardous environment, at different sites of the fumarolic areas. With such a configuration we can take advantage of the long optical path-length allowed by the multiple-pass cell (20.3m). The measured CO2 and H2O concentrations vs. time are shown. This work was supported by GNV-INGV, in the framework of the project "Development of spectroscopic integrated system for remote and continuous monitoring of volcanic gases".

Paper Details

Date Published: 1 September 2004
PDF: 7 pages
Proc. SPIE 5459, Optical Sensing, (1 September 2004); doi: 10.1117/12.545808
Show Author Affiliations
Alessandra S. Rocco, Istituto Nazionale di Ottica Applicata (Italy)
Gianluca Gagliardi, Istituto Nazionale di Ottica Applicata (Italy)
Livio Gianfrani, Univ. degli Studi di Napoli Federico II (Italy)
Giuseppe De Natale, INGV/Osservatorio Vesuviano (Italy)
Paolo De Natale, Istituto Nazionale di Ottica Applicata (Italy)

Published in SPIE Proceedings Vol. 5459:
Optical Sensing
Brian Culshaw; Anna Grazia Mignani; Rainer Riesenberg, Editor(s)

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