Application of the RASCAN Holographic Radar to Cultural Heritage Inspections

Thispaperexplorestheapplicationof the RASCANholographic radar for non-destructive subsurface imaging of works of art and architecture. This radar provides high-resolution plan-view images of the shallowsubsurface in dielectricmaterials.The radar isparticularly sensitive to smallmetallic targets, but also to variations inmoisture content.Originally developed for detection of hidden bugging devices, sounding of building construction details, and detection of landmines, here the utility of the RASCAN radar for art and architectural preservation studies is demonstrated by several bench-top experiments on stone and wood items with different subsurfacedefectsandfeatures, aswellasactual field tests on a decorativemarblemedallion in the floor of theTemple of San BiagioinMontepulciano, Italy, and Frescoes in the Church of San Rocco in Cornaredo, Italy.Historical research indicates that themedallion in San Biagiowas laid circa1590 during the funeral ceremony of a Prelatio of the family CasataCervini.Theactualburialplaceofthe Prelatioisnot recorded, butaradarscanofthemedallion, and follow-up scans of a bench-top model suggest the possibility of a cavity that could contain remains or relics. In San Rocco, small delaminations were detected behind the frescos.