Nondestructive testing and evaluation of historical monuments using thermography and electronic speckle pattern interferometry (ESPI)

Two remote and nondestructive testing techniques for the study of the decay mechanisms of stone and plaster surfaces are presented. While electronic speckle pattern interferometer (ESPI) measures the 3-D-microdeformations of the surface, transient thermography shows at the same time invisible defects and structural faults as a reaction to the impact of short heat pulses. The combination of these two different techniques demonstrates its feasibility to detect restorative work and shows the compatibility of clasical and modern substitutes and restoration techniques to historical materials.