Fluorescence Lidar Remote Sensing: Experimental Test for Investigating Black Crusts on Ancient Buildings

We report the first field experiment on the monitoring of black crusts by fluorescence lidar. Black crusts are an aesthetic and structural damage to the external parts of stone monuments mainly caused by atmospheric deposition. The experiment carried out on the cathedral (Duomo) in Pisa, Italy, demonstrates that the presence of black crusts change the fluorescence spectra of the stone substrates in both shape and absolute values. All the investigated black crusts have the similar spectral signature and characteristic behavior.