The potential of laser-induced breakdown spectrometry for real time monitoring the laser cleaning of archaeometallurgical objects

In this work, an orthogonal double pulse (DP) laser-induced breakdown spectroscopy configuration as a diagnostic tool for the restoration of archaeometallurgical samples has been developed and evaluated. Although laser-induced breakdown spectroscopy has been extensively tested in this kind of applications, this study presents an alternative method in terms of controlling the laser cleaning process of metallic object as well as real time laser-induced breakdown spectroscopy monitoring of the emission signal of the ablated material (pollutants and the structural materials). Several experimental parameters such as interpulses delay time, second laser to target distance and second pulse energy delay have also been accomplished in ancient Alexandrian coins. An enhancement of the signal emission is observed when both cleaning and analyzing lasers are combined, while no spectra signal is achieved when both lasers are operating independently. The restoration of ancient object by means of both conventional and double pulse laser cleaning arrangements is also discussed.