A Polish Discovery – Artist's Signature

Scientists in Poland have described how optical coherence tomography (OCT) – a technique most often used in medical imaging – can be used to reveal the forgery of an artist’s signature or changes in inscriptions on 100-year old paintings.
Piotr Targowski of the Institute of Physics at Nicolaus Copernicus University in Torun, Poland, notes that easel paintings prepared according to traditional techniques consists of multiple layers. The artist, for instance, first applies a glue sizing over the canvas to ensure proper adhesion of later layers. Those layers may include an outline of the painting, the painting itself, layers of semitransparent glazes and, finally, a transparent varnish.

Source: Savage, Lynn. “OCT Provides New Tool for Art Historians.” Photonics Spectra. 44.3 (2010): 76.