Laser restoration of ceramic artifacts with archeological value

A new method for restoration of ceramic surfaces, based on laser ablation of impurities has been developed. Optical pulses generated by Nd:YAG laser are used to remove a high absorbing layer (fungi) from the surface of a lower absorbing ceramic substrate. Two regimes of operation have been employed: Q-switched mode and free running mode. Analysis suggests that Q-switched mode of operation is the most efficient for cleaning processes. Densities of energy 1.60 - 1.90 J/cm2 at the fundamental wave and pulse duration 10 ns are the typical values for removing of impurities of fungi from ceramic surfaces. The second, third and forth harmonics of the Nd:YAG laser have been also used for optimization of the process of laser restoration. The absence of structural changes of the ceramics surface after the process of laser cleaning has been observed by X-ray analysis. The used ceramic substrate is dated 5000 BC- a part of the excavations near Durankulak.