SCANNING LIDAR FLUOROSENSOR FOR REMOTE DIAGNOSTIC OF SURFACES Luisa Caneve F. Colao, R. Fantoni, L. Fiorani, A. Palucci ENEA - UTAPRAD Technical Unit Development of Applications of Radiations DIM Diagnostic and Metrology Laboratory Via Enrico Fermi 45 – Frascati

LIF TECHNIQUE FOR SURFACE ANALYSIS SAMPLE Excitation UV laser Emission Specific bands of the material Methodology Laser Induced Fluorescence Process The emission of radiation by luminescent materials is observed whenever an absorption of energy sufficient to activate allowed electronic transitions occurs. Laser Induced Fluorescence is generated after the absorption of UV radiation. Typical LIF spectrum Substrate emission Elastic channels Clorophyll emission Laser Nd:YAG 266 nm, 355 nm Spectrometer nm CCD Array CHARACTERIZATION OF MATERIALS BY MEANS OF LASER-BASED TECHNIQUES

LIF SCANNING SYSTEMS Sez. 1/ 1 INFORMATION OF ANALYTICAL AND QUALITATIVE INTEREST ON DIFFERENT MATERIALS BY THE ANALYSIS OF THE EMISSION OF FLUORESCENCE CAPABILITY TO GIVE INFORMATION ON SUBSTANCES HAVING SPECIFIC SPECTRAL SIGNATURE MAIN ACTIVITIES ON CULTURAL HERITAGE PROTECTION AND RESTORATION - to recognize the different used materials - previous restoration works - presence of biodegrading agents Scanning LIF system during in field measurements Immagine 1 LIF scanning is a fast, no invasive, remote, sensible and specific technique of investigation - Compact (58x43x36 cm) - Remote (10m) - Light (15kg)

Laser Nd:YAG 266 nm, 355 nm 1.5 mJ, 10 ns, 20 Hz Spectrometer Imaging spectrograph range nm Square ICCD sensor (1024 x1024 pixel ; 13 x13 mm 2 ) L laser O collecting optics M mirrors S spectrometer C lens ( Field of view 5.7 °) D CCD array LIF LINE SCANNING SYSTEM LidArt, a new compact set up has been recently built, to increase the detection sensitivity, space resolution and data acquisition speed. Filter An image of 1.5 × 5 m 2 is scanned in less than 2 minutes at 25 m distance (spatial resolution 2mm) laser Cylindrical lens CCD spectrometer

5 DATA ACQUISITION LIF Spectrum by the selected area CCD Image

Cultural Heritage materials: stones, painted woods, decorated ceramics, frescoes, pigments (inorganic, organic), binders(historical, modern) Building materials (marble, tuff) Biodegrading agent (fungi, algae, lichens) Environment (LIDAR Fluorosensor) LIF APPLICATIONS

Hrastovije Church IN FIELD APPLICATIONS Fluorescence image A line along a crack in the wall appears 520nm Consolidants map on vault frescos Padua Baptistery Virgen del Buen Aire Chapel in the Palace of San Telmo in Seville

8 Two colours images to better document the restoration process The black corresponds to pixels with high fluorescence emission intensity, while white area to pixels with low fluorescence fluorescence image with the band at 360nm DATA PROCESSING Areas, presumably treated, with prominent F360nm emission band appear in blue; grey areas are uncertain; yellow areas are minimally treated

9 Database of reference materials necessary to the identification of the chemicals DATA ANALYSIS ACRILIC RESINS CONSOLIDANTS FUNGI STRAINS BIODEGRADING AGENTS

LIF specific advantages - Real time - In situ, no sample preparation - Remote - No destructive, minimal invasiveness - Not expensive CONCLUSIONS -…-… LIF technique can be used in security applications to identify special kinds of materials, as debris or bio-hazard components FUTURE WORK Acquisition of 3D models by Laser Range Finder can provide a sub-millimeter accuracy in the localization by the simultaneous overlap of the false color images by LIF