Optical coherence tomography (OCT) is a nondestructive imaging technique capable of imaging 3D images of thin layered structures up to a few millimeters deep. Applications within the field of material science research and cultural heritage studies are structural and stratigraphy analysis of layered objects and varnish layers.
Our OCT imaging system has an axial (depth) resolution of 3.0 μm and a lateral resolution of 4 μm in air. The system is capable of imaging high resolution cross-sectional images of varnish layers. Sample properties such as stratigraphy, layer thickness, attenuation coefficient and refractive index are accessible from the OCT signal.
Current OCT systems work by scanning the beam over the sample using galvanometric mirrors yielding scanning areas typically 10×10 mm^2, much smaller than many works of art. This limits the practical usability of the technique.
In this work we present a setup, consisting of scanning stages and the OCT device, that enables us to scan up to 20 x 20 x 0.2 cm volumes of cultural heritage. Specifically designed software regulates synchronized scanning, dynamic focus control, image registration, image segmentation and user friendly image rendering. The resulting image enables conservators to assess the condition (layers) of a large volume of an object and judge the results of resulting (restaurative) interventions.