A fluorescence imaging lidar for the control of cultural heritage

The fluorescence lidar imaging technique turns particularly useful for the control of monuments. The investigated topics range from the detection of biodeteriogens to the characterization of stones and other masonry or restoration materials, such as protective treatments. In addition, the fluorescence lidar imaging is a non-destructive technique offering the possibility of being carried out in situ without the use of scaffolding that, beside being costly, limits the access to the monument and its use. This paper presents the main technical features of a new fluorescence imaging lidar system specifically developed for the diagnostics on the cultural heritage, whose operative conditions include outdoor and indoor environments, and the possibility of monitoring vaults and ceilings. This fluorescence lidar prototype is mainly composed of a Q-switched, tripled frequency Nd:YAG laser (@355 nm), a 1 m focal length Newtonian telescope and a 300 mm focal length spectrometer coupled to an intensified, gated 512 × 512 CCD detector. Imaging is carried out via a scanning system realized with a computer controlled mirror. The lidar prototype includes also a target pointing system for referencing the acquired fluorescence images on the target.