A Portable THz Imaging System for Art Conservation

Abstract

The electromagnetic radiation, in the range from IR to X-rays, is widely used in the field of art conservation and diagnostics. In the last few years a new interest was devoted to the longer wavelengths, in the so called “THz region” of the spectrum, due to the peculiar characteristics of the radiation in this spectral range, that make it ideal for applications in this field [1]: it's low photon energy and its ability to penetrate dielectric materials. This high penetration capabilities were used to demonstrate the possibility to detect artwork hidden under layers of other dielectric materials [2]–[4]. Making use of phase-sensitive techniques it is also possible to get information on the optical properties of the materials under study and to obtain images that include spectroscopic information about the sample [5]. Moreover, radiation in the THz range is strongly reflected and absorbed by water, and this feature can be used to study degradation in mural paintings and mosaics.