| 21. |
- Grönlund, Rasmus, et al.
(författare)
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Remote laser-induced fluorescence imaging for assessment of cultural heritage
- 2005
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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)
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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
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Ingår i: [Host publication title missing].
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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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