Checkup for aging artwork-Optical tools to monitor mechanical behaviour

Deterioration of artwork is often connected to mechanical material degradation that starts on microscopic scales. Insight into decay mechanisms can therefore be obtained by monitoring microscopic deformation and displacement fields. Thus, the proper optical methods become an ideal tool for restorers and conservators, the more as they are non-intrusive and remotely applicable. We show how the scope of modern coherent metrology can be adapted to this aim. Refinements of correlation imaging, speckle interferometry and low-coherence detection provide a wealth of methods that have been applied successfully in historical objects.