| 1. |
- Andersson, Mats, et al.
(författare)
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Laser spectroscopy of gas in scattering media at scales ranging from kilometers to millimeters
- 2007
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Ingår i: Laser Physics. - 1054-660X. ; 17:7, s. 893-902
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Tidskriftsartikel (refereegranskat)abstract
- Free gases are characterized by their narrow line width, and they can conveniently be studied by laser spectroscopy. The present paper discusses the monitoring of such ambient pressure gases, which are dispersed in scattering media such as aerosol-laden atmospheres, solids, or liquids. Atmospheric work basically constitutes the well-known field of differential absorption lidar (DIAL), while the study of free gas in solids and liquids was initiated more recently under the name of GASMAS (GAs in Scattering Media Absorption Spectroscopy). We discuss the connections between the two techniques, which are extensively used in our labortory. Thus, we span the field from trace-gas mapping of gases in the lower atmosphere to gas studies in construction materials, food products, and the human body. We show that the basic ideas are very similar, while the spatial and temporal scales vary greatly.
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| 2. |
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| 3. |
- Bengtsson, Magnus, et al.
(författare)
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Fluorescence lidar imaging of fungal growth on high-voltage outdoor composite insulators
- 2005
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Ingår i: Optics and Lasers in Engineering. - : Elsevier BV. - 0143-8166 .- 1873-0302. ; 43:6, s. 624-632
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Tidskriftsartikel (refereegranskat)abstract
- Remote fluorescence imaging of fungal growth on polymeric high-voltage insulators was performed using a mobile lidar system with a laser wavelength of 355 nm. Insulator areas contaminated by fungal growth could be distinguished from clean surfaces and readily be imaged. The experiments were supported by detailed spectral studies performed in laboratory using a fibre-optic fluorosensor incorporating an optical multi-channel analyser system (OMA) and a nitrogen laser emitting radiation at 33 7 nm.
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| 4. |
- Bengtsson, Magnus, et al.
(författare)
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Fungus covered insulator materials studied with laser-induced fluorescence and principal component analysis
- 2005
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 0003-7028 .- 1943-3530. ; 59:8, s. 1037-1041
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Tidskriftsartikel (refereegranskat)abstract
- A method combining laser-induced fluorescence and principal component analysis to detect and discriminate between algal and fungal growth on insulator materials has been studied. Eight fungal cultures and four insulator materials have been analyzed. Multivariate classifications were utilized to characterize the insulator material, and fungal growth could readily be distinguished from a clean surface. The results of the principal component analyses make it possible to distinguish between algae infected, fungi infected, and clean silicone rubber materials. The experiments were performed in the laboratory using a fiber-optic fluorosensor that consisted of a nitrogen laser and an optical multi-channel analyzer system.
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| 5. |
- Bengtsson, Magnus, et al.
(författare)
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Lidar fluorescence measurements of algal growth on electrical insulators
- 2003
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Ingår i: 2003 Conference on Lasers and Electro-Optics Europe (CLEO/Europe 2003) (IEEE Cat. No.03TH8666). - 0780377346 ; , s. 473-473
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Konferensbidrag (refereegranskat)abstract
- Fluorescence measurements using lidar techniques have been shown to be useful for monitoring of algal growth on e.g. historical monuments. In this experiment similar measurements were performed on electrical insulators to examine the correlation between algal growth and the quality of the insulator, a factor of importance in the high-voltage grid management
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| 6. |
- Bengtsson, Magnus, et al.
(författare)
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Remote laser-induced breakdown spectroscopy for the detection and removal of salt on metal and polymeric surfaces
- 2006
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 60:10, s. 1188-1191
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Tidskriftsartikel (refereegranskat)abstract
- The detection of contamination such as salt in outdoor high-voltage insulator systems and its subsequent removal are vital for a reliable transmission of electric power. Remote detection of salt on a copper metal surface was carried out by using a mobile laser-induced breakdown spectroscopy (LIBS) Lidar system with a laser wavelength of 355 nm. Detection of salt on a polymeric high-voltage insulator was obtained when an additional lens was inserted into the beam path, and the number of photons that was detected could be calculated by using a calibrated white light source. Ablative cleaning could readily be carried out with LIBS and was verified by observing the disappearance of the sodium D-line emission.
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| 7. |
- Bennett, M, et al.
(författare)
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Joint application of Doppler Lidar and differential absorption lidar to estimate the atomic mercury flux from a chlor-alkali plant
- 2006
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 40:4, s. 664-673
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Tidskriftsartikel (refereegranskat)abstract
- We have combined differential absorption lidar (DIAL) measurements of mercury concentrations downwind of a chloralkali plant (Rosignano Solvay) with measurements of wind profiles made with a Doppler Lidar based on modern fibreoptic technology. Since the flux of pollutant is equal to the cross-wind integral of the product of concentration and wind speed, this should permit us to make a more precise estimate of the fugitive emission of mercury from the plant than could be obtained by using anemometer measurements of the wind. The flux was estimated to be 54g Hgh(-1) using an anemometer on the plant building; 49g Hgh(-1) using an anemometer on a nearby 10m mast; and 48g Hgh(-1) using wind speed corrections estimated from the Doppler Lidar measurements. Because of difficulties with the range resolution of the Doppler Lidar, the precision of this estimate was not as good as it should have been, though the difference from the rooftop anemometer remains statistically significant. Corrections of this magnitude are irrelevant to the Rosignano plant, where the emission rate varies strongly with the meteorological conditions. Where a precise estimate of a steady flux is required, however, reliable measurements of the wind profile in the wake of the source are essential. Doppler Lidar provides a possible method for acquiring such measurements. (c) 2005 Elsevier Ltd. All rights reserved.
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| 8. |
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| 9. |
- Dernfalk, Andreas, 1975, et al.
(författare)
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Laser-induced fluorescence spectroscopy for detection of biological contamination on composite insulators
- 2003
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Ingår i: In Proc. 13th International Symposium on High Voltage Engineering, Delft, Netherlands.
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Konferensbidrag (refereegranskat)abstract
- A new technique for remote detection of biological contamination on high-voltage outdoor insulators has been investigated. The technique, which is based on laser-induced fluorescence (LIF) spectroscopy, has been applied to study surfaces of real silicon rubber insulators from a distance of approximately 60 m. Measurements were performed outdoors on a number of clean, as well as, biologically contaminated insulators. Several types of biological contamination were included, as five of the studied insulators had become covered when installed in Sweden, and another three had been contaminated by fungal growth in laboratory. Fluorescence spectra obtained from the surfaces of the described insulators are presented and the applicability of the technique is discussed and compared with photographic methods.
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| 10. |
- Grönlund, Rasmus, et al.
(författare)
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Elemental mercury emissions from chlor-alkali plants measured by lidar techniques
- 2005
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 39:39, s. 7474-7480
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Tidskriftsartikel (refereegranskat)abstract
- Differential absorption lidar (DIAL) techniques have been utilized to measure elemental gaseous mercury fluxes from mercury cell chlor-alkali (MCCA) plants as a part of the European Union funded European mercury emissions from chlor-alkali plants (EMECAP) project. Three plants have been selected as study objects and a total of six measurement campaigns have been performed, one intercalibration campaign and five flux evaluation campaigns, in both winter and summer. The measurements were carried out using the Swedish optical parametric oscillator-(OPO) based mobile lidar system developed at Lund Institute of Technology. The study shows large differences in the mercury emissions measured in winter or summer and at the different plants. The average values for the campaigns ranged from 6 g h(-1) in the winter campaign at the Swedish plant to 54 g h(-1) in the summer campaign at the Italian plant.
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| 11. |
- Grönlund, Rasmus, et al.
(författare)
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Fluorescence lidar multispectral imaging for diagnosis of historical monuments - Övedskloster, a Swedish case study
- 2007
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Ingår i: Springer Proceedings in Physics. - 0930-8989. ; 116, s. 583-591
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Konferensbidrag (refereegranskat)abstract
- A fluorescence lidar measurement has been performed on the castle Övedskloster in Sweden. A mobile system from the Lund University was placed at ~40 m distance from the sandstone façade. The lidar system, which uses a frequency-tripled Nd:YAG laser with a 355-nm pulsed beam, induces fluorescence in each target point. Areas were studied by using whisk-broom scans. The possibility of detecting biodeteriogens on the surface and characterization of materials was confirmed. The method can be a tool for conservation planning and status control of the architectural heritage where fluorescence light can point out features that are not normally visible under natural illumination.
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| 12. |
- Grönlund, Rasmus, et al.
(författare)
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Laser-Induced Fluorescence for Assessment of Cultural Heritage
- 2006
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Konferensbidrag (refereegranskat)abstract
- Remote imaging measurements of laser-induced fluorescence have been performed, with application towards cultural heritage. Measurement campaigns have been performed at, e.g., the Coliseum in Rome. Differences in fluorescence spectra from different points were found and images corresponding to different features could be produced for thematic mapping.
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| 13. |
- Grönlund, Rasmus, et al.
(författare)
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Laser-induced fluorescence imaging for studies of cultural heritage - art. no. 66180P
- 2007
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Ingår i: O3A: Optics for Arts, Architecture, and Archaeology. - : SPIE. - 1996-756X .- 0277-786X. - 9780819467607 ; 6618, s. 6180-6180
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Konferensbidrag (refereegranskat)abstract
- Laser-induced fluorescence for remote imaging of historical monuments is an established technique, which in this work has been used in measurement campaigns at the Coliseum and the Baptistery of San Giovanni in Laterano in Rome, Italy. The results presented here are examples that show that biodeteriogens can be monitored and that. materials can be identified. Also, cleaned and soiled areas on the stone can be localized and differences between soiling can be found, which may be useful in the sustainable conservation for mapping and evaluation.
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| 14. |
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| 15. |
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| 16. |
- Grönlund, Rasmus
(författare)
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Lidar Techniques for Environmental Monitoring
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atoms and molecules absorb and emit light at certain, welldefined wavelengths, and this forms the basis of spectroscopy. The wavelengths are given by the discrete energy levels of the atoms/molecules. When illuminated by light of a suitable wavelength, the light will be absorbed, making it possible to deduce information on the presence and concentration of various elements and compounds. When atoms or molecules have been excited, they may spontaneously relax to their ground state, emitting species-specific light, defined by the energy levels. This concept can be used to induce fluorescence in the material, which again can be used to analyse the properties of the sample. Light detection and ranging techniques can be used to perform remote spectroscopic measurements. The sample is probed with a laser beam and the resulting light can be collected with a telescope of sufficient size. Useful results can be deduced at ranges as large as several kilometres, although, in this work the range was never more than a kilometre. In the work presented in this thesis, differential absorption lidar measurements have been performed to determine mercury fluxes from pollution sources. These measurements have been performed as field campaigns in different parts of Europe. Some measurements have been made at chlor-alkali factories, and one campaign at an abandoned mercury mine. Moreover, fluorescence lidar techniques have been used for remote investigation of façades of historical buildings and electrical insulators. These measurements have been performed both in a laboratory setting (albeit still remotely through an ordinary atmosphere) and as field campaigns. Biological contamination and surface treatment chemicals can be monitored, and types of stone in façades can be characterized. Finally, the remote laser-induced breakdown spectroscopy technique has been extended to make imaging possible. These measurements can be used to characterize materials in surface layers, which may be useful in cultural heritage monitoring.
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| 17. |
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| 18. |
- Grönlund, Rasmus, et al.
(författare)
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Mercury emissions from the Idrija mercury mine measured by differential absorption lidar techniques and a point monitoring absorption spectrometer
- 2005
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 39:22, s. 4067-4074
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Tidskriftsartikel (refereegranskat)abstract
- Mercury emission measurements from the ldrija mercury mine in Slovenia were performed during an early November 2003 campaign, where the differential lidar technique was used to map mercury concentrations and an attempt was made to quantify the total mercury flux from the most contaminated area, the abandoned cinnabar roasting oven complex. Lidar concentration data were compared with data recorded with a Zeeman modulated atomic absorption instrument, operated from a vehicle equipped with a GPS localization system. Concentrations and fluxes were comparatively low due to low temperature and rainfall. The average flux from the distillation plant was measured to approximately 2 g h(-1).
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| 19. |
- Grönlund, Rasmus, et al.
(författare)
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Remote imaging laser-induced breakdown spectroscopy and laser-induced fluorescence spectroscopy using nanosecond pulses from a mobile lidar system
- 2006
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Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 60:8, s. 853-859
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Tidskriftsartikel (refereegranskat)abstract
- A mobile lidar system was used in remote imaging laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF) experiments. Also, computer-controlled remote ablation of a chosen area was demonstrated, relevant to cleaning of cultural heritage items. Nanosecond frequency-tripled Nd:YAG laser pulses at 355 nm were employed in experiments with a stand-off distance of 60 meters using pulse energies of up to 170 mJ. By coaxial transmission and common folding of the transmission and reception optical paths using a large computer-controlled mirror, full elemental imaging capability was achieved on composite targets. Different spectral identification algorithms were compared in producing thematic data based on plasma or fluorescence light.
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| 20. |
- Grönlund, Rasmus, et al.
(författare)
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Remote imaging laser-induced breakdown spectroscopy and remote cultural heritage ablative cleaning
- 2005
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Ingår i: Optics Letters. - 0146-9592. ; 30:21, s. 2882-2884
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Tidskriftsartikel (refereegranskat)abstract
- We report, for what we believe to be the first time, on remote imaging laser-induced breakdown spectroscopy (LIBS). Measurements have been performed by using a tripled Nd:YAG laser working at 355 nm with 170 mJ pulse energy, with an expanded beam that is focused onto a target at 60 m distance. The LIBS signal is detected by using an on-axis Newtonian telescope and an optical multichannel analyzer. The imaging is performed by scanning the laser beam on the target. The same setup is also used in demonstrations of remote laser ablation for cleaning of contaminated objects with applications toward cultural heritage.
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| 21. |
- Grönlund, Rasmus, et al.
(författare)
-
Remote laser-induced fluorescence imaging for assessment of cultural heritage
- 2005
-
Ingår i: 2005 Conference on Lasers and Electro-Optics Europe. - 0780389743 ; , s. 685-685
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose to perform remote laser-induced fluorescence imaging for assessment of cultural heritage. The experiments are performed using the lidar system consist of frequency-tripled Nd:YAG laser at 355 nm with a spot size of ~4 cm diameter and the signal is collected using a coaxial 40-cm-diameter Newtonian telescope. The fluorescence light is focused into an optical fibre and guided a time-gated optical multichannel analyser system, where the fluorescence spectrum is recorded. Then the laser directed to the next point and thus a fluorescence image can be produced
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| 22. |
- Grönlund, Rasmus, et al.
(författare)
-
Remote LIBS and Raman imaging for assessment of cultural heritage
- 2005
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Ingår i: 2005 Conference on Lasers and Electro-Optics Europe. - 0780389743 ; , s. 684-684
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose to perform remote laser-induced breakdown spectroscopy (LIBS) and Raman imaging of historical monuments to assess the state of a building. The lidar system is equipped with a Nd:YAG pumped optical parametrical oscillator (OPO) system, allowing laser radiation in the wavelength range 220 nm-4 μm. The laser radiation can be sent through a roof-top dome which can steer the radiation onto the point of interest
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| 23. |
- Grönlund, Rasmus, et al.
(författare)
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Remote Multicolor Excitation Laser-Induced Fluorescence Imaging
- 2006
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Ingår i: Laser Chemistry. - : Hindawi Limited. - 0278-6273 .- 1476-3516. ; 2006, s. 57934-57934
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Tidskriftsartikel (refereegranskat)abstract
- Remote laser-induced fluorescence of stone materials was performed with application towards cultural heritage. Fluorescence was induced in targets ∼60 m from a mobile lidar laboratory by ultraviolet laser light, either from a frequency-tripled Nd:YAG laser or from an optical parametric oscillator system. Analysis was performed on combined spectra from the different excitation wavelengths and it was noted that important additional information can be gained when using several excitation wavelengths.
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| 24. |
- Grönlund, Rasmus, et al.
(författare)
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Studies of free gas in scattering media at micro- and macroscopic scales
- 2006
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Ingår i: Proceedings of International Symposium on Biophotonics, Nanophotonics and Metamaterials. ; , s. 42-45
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Konferensbidrag (refereegranskat)abstract
- Free gases in scattering media and different techniques for such studies are discussed in the present paper. Connections between two techniques that constitute a major research area at our laboratory are presented. One of the techniques concerns measurements of free gas in scattering media, such as human tissue and food products, on a small scale, while the other one is a technique for trace-gas measurements in the lower atmosphere. We show that the basic ideas are very similar and that, by applying the knowledge obtained on one scale to the other, little differences exist. This study motivates us to perform a measurement linking the two techniques.
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| 25. |
- 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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| 26. |
- Guan, Zuguang, et al.
(författare)
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LIDAR technique for Remote Gas Analysis in Solid Scattering Media
- 2009
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Ingår i: Asia Optical Fiber Communication & Optoelectronic Exposition & Conference, 2008. AOE 2008.. - 9781557528636
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Konferensbidrag (refereegranskat)abstract
- LIDAR techniques are used to measure gases in solid scattering media remotely, by analyzing the differential absorption observed in the multiple scattering light. The gas exchange (O-2/N-2) in polystyrene foam is monitored. (C)2008 Optical Society of America
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| 27. |
- Hällström, Jenny, et al.
(författare)
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Documentation of soiled and biodeteriorated facades: a case study on the Coliseum, Rome, using hyperspectral imaging fluorescence lidars
- 2009
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Ingår i: Journal of Cultural Heritage. - : Elsevier BV. - 1778-3674 .- 1296-2074. ; 10:1, s. 106-115
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Tidskriftsartikel (refereegranskat)abstract
- Non-invasive documentation of historic façades with fluorescence lidar techniques can provide helpful information for the cultural heritage sector, especially when large areas outdoors are to be examined. This paper presents a case study on the Coliseum, Rome, where both cleaned and heavily soiled areas of the monument were scanned and analysed with two fluorescence lidar systems. Biodeterioration processes have also been addressed during the experiment with the aim of assessing the colonisation extent on selected areas of the monument. Results show the usefulness of a mobile fluorescence lidar system for documentation and survey of large surfaces with complex conditions without limiting the public access to the monument.
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| 28. |
- Hällström, Jenny, et al.
(författare)
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Fluorescence lidar multispectral imaging for historical monuments, the Lateran Baptistery interdisciplinary project
- 2006
-
Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- Introduction For the future conservation, restoration and daily maintenance the need for developing non-destructive and in-situ investigations is vital. At Lund University in Sweden an interdisciplinary research project is being held aiming at, with the help of a mobile system of remote fluorescence lidar, survey and study the facades of historic monuments, and to develop the method and its application for the cultural heritage sector. Earlier studies using the fluorescence lidar technique has been undertaken at, for example, Parma, Lund and Pisa Cathedral. During the winter 2005 two field studies were performed in Rome, one on parts of the Flavian Amphitheatre Coliseum, and the other on parts of the Lateran Baptistery. The studies were performed from remote and with no need for taking samples. The aim was to identify different materials, different biodeteriogens and other objectives not yet visible for the human eye. Objectives for the project The primary aim of the research project is to analyse the potential of the fluorescence lidar technique in building investigation. Furthermore, to establish a scientific remote-sensing method for surveying and analysing the historical facade that is non-destructive and takes place in-situ. The aim of the fluorescence lidar method is to use point-monitoring and scanning of areas which can provide multispectral images in order to identify different types of stones, their origin, different biodeteriogens and conservation chemicals. A specific aim of the project is to develop the method in comparison with existing documentation methods, to improve the understanding of the built heritage and to provide a basis for new interventions, documentation and maintenance. Methods Fluorescence techniques make it possible to extend the application of fluorescence spectroscopy to the outdoor environment (remote sensing), with sometimes large distances and uncontrollable background light. The ultra-violet laser pulse used in the experiments (usually 355 nm and 308 nm) is directed to the point of interest, exciting atoms and molecules in the material, which then relax emitting fluorescence light. The unique fluorescence spectra from each point taken can then be analysed and identified. By applying a function to the different spectra, each point is assigned a value, and from this a false-colour coded image can be produced, indicating points with different properties, revealing e.g. different materials and earlier treatments. Lateran Baptistery field study The study of the Lateran Baptistery in Rome is a co-operation between Lund University, the Swedish Institute in Rome, CNR-IFAC in Florence, and the research project led by Dr. O. Brandt and Dr. G. Eriksdotter, from the Swedish Institute, the Vatican Museums and the Pontifical Institute of Christian Archaeology, also involving Italian and Swedish archaeology students who has performed a stratigraphic analysis during 2005. The Baptistery, part of the San Giovanni in Lateran church complex, dates back to the fourth hundred-century AC. The analysis from the lidar campaign and the stratigraphic studies are now being cross-examined and the analysis aims to identify brick material and if possible distinguish different building and restoration phases of the baptistery.
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| 29. |
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| 30. |
- 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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| 31. |
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| 32. |
- 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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| 33. |
- Raimondi, V., et al.
(författare)
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The fluorescence lidar technique for the remote sensing of photoautotrophic biodeteriogens in the outdoor cultural heritage: A decade of in situ experiments
- 2009
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Ingår i: International Biodeterioration & Biodegradation. - : Elsevier BV. - 1879-0208 .- 0964-8305. ; 63:7, s. 823-835
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Tidskriftsartikel (refereegranskat)abstract
- Fluorescence lidar is a non-invasive, remote sensing technique that makes it possible to extend the application of the laser-induced fluorescence technique to the outdoor environment where uncontrolled, external conditions must be met. Although initially developed for the investigation of marine environment and vegetation, in the past decade this technique has been successfully applied to the field of the cultural heritage. Among other applications, the detection and characterisation of photoautotrophic biodeteriogens has become very promising: the method is based on the detection of chlorophyll a fluorescence, while fluorescent accessory pigments can be exploited for a rough classification of the biodeteriogens present on the surface. Early experiments on monuments date back to the mid 1990s, when fluorescence lidar point measurements were conducted on the Cathedral and Baptistery of Parma, Italy. Subsequently, the technique has taken further advantage of the introduction of imaging capabilities in lidar instrumentation and this has led to the acquisition of hyperspectral fluorescence maps over extended areas of several monuments from distances as great as 80 m. Here, we present the main achievements obtained in the outdoor cultural heritage so far and the latest developments in the technique. (C) 2009 Elsevier Ltd. All rights reserved.
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