A versatile system for in-situ speckle and thermography-based diagnostics of artifacts

Holographic nondestructive techniques already showed their effectiveness in detecting structural defects on or beneath the surface of historical artifacts, not emerging from conventional visual inspections. Unfortunately, such tools are difficult to be operated out of the stability conditions guaranteed by an optics laboratory. The peculiar features of many works of art, however, make often impracticable their transport to dedicated facilities. In this work, a compact, stable, portable holographic system was designed and implemented: the resulting apparatus allows in-situ acquisitions, even in non-laboratory conditions, and provides rapid and clearly interpretable diagnostic information by the completely non-invasive procedure of speckle pattern photography (SPP). Complementary data are furnished by an integrated infrared thermography system. A map of the artifact surface can be obtained, representing the distribution of defects and their extension. The technique will hopefully help or replace conventional methods, more invasive or less systematic (visual inspections, surface tapping), still largely used for the same purposes.