Artwork Inspection by Shearography with Adapted Loading

Abstract

Methods for the investigation of the surface as well as methods to find subsurface and structure weakening defects are of special interest in the field of art conservation. Shearography is a self-referencing interferometric technique that was proven to be useful for the robust detection of various defects under practical conditions. In the past the investigation of artwork using shearography was mainly done by thermal loading. But other loading techniques, like pressure, vibration and humidity change can be applied with advantage. In this paper we investigate the influence of different loading types and mechanisms on the sensitivity of defect detection on artwork considering their possible impact on the intact part of the artwork. At different samples we will show that a kind of mechanic loading provides a suitable method to detect delaminations and cracks without damaging the paintings. For other typical defects like holes, or trapped air other types of loading like the thermal one is more suitable.