In addition to concerns about the appearance of a display, curators of art galleries are also concerned about conservation of the artwork and their authenticity. Microscopes have played a role in these latter activities since the 1930s. Various imaging techniques, including X-radiography, infrared reflectography, macrophotography, UV-fluorescence and raking light (light source at a low angle to the surface) imaging have their advantages and disadvantages. Confocal microscopy is most useful compared to the other methods for the purpose of examination of subsurface structure, but the close working distance (a few mm) makes it precarious to use on valuable masterpieces. More recently, Haida Liang, Marta Cid, Radu Cucu, George Dobre, Adrian Podoleanu, Justin Pedro, and David Sauders have demonstrated the usefulness of optical coherence tomography (OCT) for non-destructive examination of artwork. OCT, as discussed previously in this column, is more commonly used to examine biological specimens.