Investigating the Layer Structure and Insect Tunneling on a Wooden Putto Using Robotic-Based THz Tomography

The restoration of an art object should be as minimal as possible but also as much as necessary. A previous accurate analysis of the object is therefore essential. In the present work, we show how THz time-of-flight tomography can contribute to the determination of the actual state of a three-dimensional object. We investigated the sub-surface structure of a wooden putto (wood carving of an infant) with a robotic THz time-domain system. With the system it is possible to investigate delamination of polychrome and preparation layers as well as damages on the wooden substrate due to insect tunneling. In addition, the technique enables the restorer to find hidden damages of the object that cannot be seen by visual inspection only.