| 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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