Paintings' investigation by means of tomographic and multispectral imaging

The application of multispectral nondestructive techniques to art and archaeology provides reliable qualitative and often quantitative information, thus providing the understanding of the technical and intellectual know-how of the artists or craftsmen of the period under study, and - as for the museum's conservators - the needed information for conservation and restoration of damaged or degraded objects. Availability of a portable apparatus represents a strong constraint for many analyses to be performed in situ, and the infrared and ultraviolet spectrometry is then a suitable technology for this kind of analysis. Moreover, a portable Compton spectrometer has been developed and applied to investigation of paintings, thus complementing usual IR and UV analyses. A multispectral digital system is presented, ranging from infrared radiation to visible light, ultraviolet fluorescence and gamma- and X-ray spectroscopy, in order to perform suitable analyses of paintings on wood or canvas, preliminary to any restoration or cleaning. A few applications are discussed, concerning two Raphael's and Vasari's and Pietro Lorenzetti's works.