Microsampling of Veliky Novgorod frescoes using laser ablation.

Laser ablation is known to be a helpful tool in the restoration of objects of cultural heritage, for example, for surface cleaning and spectroscopic study including microsampling. An advantage of the technique as a sampling method is related to the resulting size of microsamples without visible traces on the surface of the original object, which makes it possible to keep the sample visually unchanged. This work extends the scope of laser ablation as a sampling method that we proposed earlier for paint layers. The technique is employed on real fragments of fresco paintings of different colors, which were discovered as a result of underwater archaeological research and provided by Novgorod State United Museum. The results of sampling by nanosecond laser ablation at wavelengths of 1064 and 532 nm are compared. Based on the comparison, a conclusion regarding parameters of radiation for ablation is drawn. The microsamples are studied using Raman microspectroscopy. [ABSTRACT FROM AUTHOR]