Fluorescence lifetime imaging for the analysis of works of art: application to fresco paintings and marble sculptures

We have recently developed a portable system for advanced fluorescence investigation of works of art. The system is based on the measurement of both the time dependent and spectral features of fluorescence emission, after excitation with UV laser pulses. The technique is aimed at localising and identifying organic and inorganic compounds present on the surface of artworks. The time dependence of the emission is analysed with a fluorescence lifetime imaging apparatus, which allows us to measure the map of the fluorescence lifetime, combined with a portable spectrometer for recording fluorescence spectra of selected points. The characterization of the compounds present on the art object's surfaces is carried out with analytical measurements on micro-samples collected with the assistance of the fluorescence maps. These methods have been successfully applied to characterise the fresco paintings of Filippo Lippi in the cathedral of Prato and to study the contaminants on the surface of Michelangelo's David in Florence.