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Träfflista för sökning "WFRF:(Grönlund Rasmus) ;spr:eng;srt2:(2007)"

Sökning: WFRF:(Grönlund Rasmus) > Engelska > (2007)

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1.
  • Andersson, Mats, et al. (författare)
  • Laser spectroscopy of gas in scattering media at scales ranging from kilometers to millimeters
  • 2007
  • Ingår i: Laser Physics. - 1054-660X. ; 17:7, s. 893-902
  • 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.
  • Grönlund, Rasmus, et al. (författare)
  • Fluorescence lidar multispectral imaging for diagnosis of historical monuments - Övedskloster, a Swedish case study
  • 2007
  • Ingår i: Springer Proceedings in Physics. - 0930-8989. ; 116, s. 583-591
  • 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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3.
  • Grönlund, Rasmus, et al. (författare)
  • Laser-induced fluorescence imaging for studies of cultural heritage - art. no. 66180P
  • 2007
  • Ingår i: O3A: Optics for Arts, Architecture, and Archaeology. - : SPIE. - 1996-756X .- 0277-786X. - 9780819467607 ; 6618, s. 6180-6180
  • 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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4.
  • Grönlund, Rasmus (författare)
  • Lidar Techniques for Environmental Monitoring
  • 2007
  • 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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  • Resultat 1-4 av 4

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