Non-Contact Ultrasonic Exploration of Ancient Paintings

Artwork are complex structures formed by multiple layers of materials with different properties and thicknesses. They are fragile structures and can be damaged by exposure to temperature, humidity, and vibrations. Techniques such as raking light, x-rays, infrared and UV provide restorers with some information about the condition of the work and its past. The ultrasonic technique, unlike the others, uses elastic waves to provide information about the mechanical characteristics of the materials. In this work we have developed a system that uses focused air-coupled transducers together with continuous motor scanning devices in order to perform experimental tests on several old paintings.