What is believed to be the first fluorescence imaging of the facades of a historical building, which was accomplished with a scanning fluorescence lidar system, is reported. The mobile system was placed at a distance of ~60 m from the medieval Lund Cathedral (Sweden), and a 355-nm pulsed laser beam was swept over the stone facades row by row while spectrally resolved fluorescence signals of each measurement point were recorded. By multispectral image processing, either by formation of simple spectral-band ratios or by use of multivariate techniques, areas with different spectral signatures were classified. In particular, biological growth was observed and different stone types were distinguished. The technique can yield data for use in facade status assessment and restoration planning.
© 2001 Optical Society of America
(100.2960) Image processing : Image analysis
(120.0280) Instrumentation, measurement, and metrology : Remote sensing and sensors
(260.2510) Physical optics : Fluorescence
(280.3640) Remote sensing and sensors : Lidar
(300.2530) Spectroscopy : Fluorescence, laser-induced
Petter Weibring, Thomas Johansson, Hans Edner, Sune Svanberg, Barbro Sundnér, Valentina Raimondi, Giovanna Cecchi, and Luca Pantani, "Fluorescence Lidar Imaging of Historical Monuments," Appl. Opt. 40, 6111-6120 (2001)