Laser surface cleaning of stones and some metal objects

Abstract

Iron, copper and stone samples were cleaned by Nd: YAG laser using different number of nano laser pulses at variable intensities. Fundamental (1.06 µm) and frequency doubled (0.53 µm) wavelengths cleaning efficiency was tested by measuring the crust and oxide removal rate. A laboratory environmental chamber was built and utilized to study the effect of processing gas on the cleaning process. Surface ref lectivity, SEM and optical microscope investigations indicated the effectiveness of Nd: YAG laser cleaning without damaging the surface. The use of high laser pulse energies helped achieving reasonably good and fast cleaning, whereas low laser energy required larger number of pulses, but ensured safe cleaning. Optimum results were obtained when using the fundamental laser wavelength under O2 environment.