Integration study among flying spot laser thermography and terahertz technique for the inspection of panel paintings

Conservation of artworks is of paramount importance nowadays around the world. Clever conservation by using non-destructive testing techniques is highly appreciated by restorers and art historians. Among these, a special set-up working into the infrared region is the flying spot laser thermography technique that uses a punctual stimulus to transfer the heat from the source into the artwork. In this way, the precious surface is gently heated by avoiding any type of damage, such as color changes and/or shrinkage and warpage effects. To the best of our knowledge, the flying spot laser thermography technique, in the configuration proposed, has been used here for the first time in the cultural heritage field. It was applied in combination with terahertz inspection, an emergent technique in the field of art research, completely non-invasive and safe for the operator. The target to be inspected was a panel painting executed by following the rules dictated by the art master Cennino Cennini. Results demonstrated how such an integrated approach is plausible to provide robust information concerning invisible defects to the naked eye.