| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
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| 8. |
- 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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| 9. |
- 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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| 10. |
- 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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