| 1. |
- Guan, Zuguang, et al.
(författare)
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Gas analysis within remote porous targets using LIDAR multi-scatter techniques
- 2008
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Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 93:2-3, s. 657-663
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Tidskriftsartikel (refereegranskat)abstract
- Light detection and ranging (LIDAR) experiments are normally pursued for range resolved atmospheric gas measurements or for analysis of solid target surfaces using fluorescence of laser-induced breakdown spectroscopy. In contrast, we now demonstrate the monitoring of free gas enclosed in pores of materials, subject to impinging laser radiation, employing the photons emerging back to the surface laterally of the injection point after penetrating the medium in heavy multiple scattering processes. The directly reflected light is blocked by a beam stop. The technique presented is a remote version of the newly introduced gas in scattering media absorption spectroscopy (GASMAS) technique, which so far was pursued with the injection optics and the detector in close contact with the sample. Feasibility measurements of LIDAR-GASMAS on oxygen in polystyrene foam were performed at a distance of 6 m. Multiple-scattering induced delays of the order of 50 ns, which corresponds to 15 m optical path length, were observed. First extensions to a range of 60 m are discussed. Remote observation of gas composition anomalies in snow using differential absorption LIDAR (DIAL) may find application in avalanche victim localization or for leak detection in snow-covered natural gas pipelines. Further, the techniques may be even more useful for short-range, non-intrusive GASMAS measurements, e.g., on packed food products.
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| 2. |
- Hällström, Jenny, et al.
(författare)
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Remote fluorescence lidar imaging of monuments: the Coliseum and the Lateran Baptistery in Rome
- 2008
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Ingår i: LASERS IN THE CONSERVATION OF ARTWORKS. - 9780415475969 ; , s. 169-175
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Konferensbidrag (refereegranskat)abstract
- On site remote laser-induced fluorescence measurements have been performed with application towards non-movable objects. This paper describes the application of non-invasive hyperspectral fluorescence imaging to two masonry monuments, the Coliseum and the Lateran Baptistery in Rome, during a joint Italian-Swedish experiment. The mobile systems of Lund Institute of Technology, Sweden, and CNR-IFAC, Italy, were placed at the distance of 18-65 m from the façades for the documentation and characterization of surfaces, including materials, protective treatments, biodeteriogens and historic layers.
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| 3. |
- Palombi, Lorenzo, et al.
(författare)
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Hyperspectral fluorescence lidar imaging at the Colosseum, Rome
- 2008
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Ingår i: Optics Express. - 1094-4087. ; 16:10, s. 6794-6808
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence lidar techniques offer considerable potential for remote, non-invasive diagnostics of stone cultural heritage in the outdoor environment. Here we present the results of a joint Italian-Swedish experiment, deploying two hyperspectral fluorescence lidar imaging systems, for the documentation of past conservation interventions on the Colosseum, Rome. Several portions of the monument were scanned and we show that it was possible to discriminate among masonry materials, reinforcement structures and protective coatings inserted during past conservation interventions, on the basis of their fluorescence signatures, providing useful information for a first quick, large-scale in situ screening of the monument.
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