For the first time, the LC-OCT of the Laboratory of Optics and Biosciences was moved and allowed to carry out analyses on works of art within the painting workshop of the Institut National du Patrimoine. This technique allows to make a three-dimensional image at the micrometer scale without contact and non-invasive for the studied object. This campaign of measurements has allowed to bring elements of answers on the presence of one or several layers of varnish, their thickness, the effects of a protocol of varnish removal, the characterization of surface degradation at the level of the varnish layer.