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Digital shearography is an interferometric technique, which is often used for defect detection on composite structures. The measurement is fast and non‐destructive and thus suitable for the application to cultural heritage. However, a major drawback of the technique is the indirect measurement, because surface strain is used to detect subsurface defects. So the determination of depth, size, and type of the defects is rather difficult. To overcome this issue, we use a combination of finite element method simulation and shearographic measurement. Due to the comparison of both data sets, the inverse problem can be solved in a more reliable way. In this paper, we investigate the application of finite element method simulation for an improved defect detection on anisotropic material. We validate the technique on a wooden sample with notches on the backside.

Because artworks are a major part of our culture their preservation is of great importance and therefore they need to be protected from any damage. But the change of environmental conditions like temperature or humidity leads to internal stress, which can result in different defects like delaminations or cracks. The deteriorations occurring due to ageing or transport are often small and invisible, but they can enlarge and produce new irreversible damages. Therefore it is important to detect small changes in the surface as well as deteriorations under the surface. A combination of fringe projection and shearography data is a very suitable method to fulfill this task. While fringe projection is used to determine the surface structure, the shearography gives information about the strain occurring due to loading, which allows conclusions about weaknesses in the internal structure. We optimized both techniques for the use in the preservation of artwork and combined the resulting data by a mapping process. In this paper we present the advantages and also the limits, which need to overcome.