Stimulated infrared thermography application to the conservation of heritage wall paintings: interest of a material and software combined approach

The study and analysis of defects in wall paintings is possible by stimulated infrared thermography, this approach is of great interest to the scientific community responsible for the conservation and restoration of these works of art. The work presented consists in identifying the best way to stimulate and analyze the thermal signals measured on these works of art in order to reveal defects invisible to the naked eye such as internal decohesions. In the case of wall paintings, for example, optical effects associated with the presence of a pictorial layer can degrade this detection. To do this, we compared two excitation modes of an academic sample, excitation using conventional halogen sources emitting in the visible and near infrared and an excitation source emitting in the mid-infrared. We compared the two excitation modes and applied a postprocessing to these two experimental approaches: SVD. The results presented made it possible to observe the interest of infrared sources and the additional contribution made by post-processing of the SVD type.