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This paper presents the results of the morphological and chemical changes on the surface of an Iranian ceramics sample irradiated by a Transversely Excited Atmospheric (TEA) CO2 and an Nd:YAG laser. The sample originates from the archeological site of Yazd (Iran) and is assumed to have been a part of an aqueduct. The effect of laser parameters (energy density (fluency), number of pulses and wavelength) on the induced changes was studied. The tests were performed in order to establish the mechanism of the interaction with the fluence above the damage threshold. This is an essential parameter in the use of lasers for cleaning as well as for eliminating surface defects such as cracks, by melting superficial layers and thus strengthening the objects in question. Another objective was to obtain as much as possible information about the material composition necessary for the conservation and restoration of this ceramics. A TEA CO2 (10.6 mu m wavelength, pulse duration 100 ns (Full Width at Half Maximum - FWHM)) laser and an Nd:YAG laser (wavelength 1064 nm and 532 nm, FWHM = 150 ps) have been used for the surface treatment. Laser fluences were in the range of 1-20 J/cm(2). The ceramics surface morphology modifications, induced by pulsed lasers, were characterized by a scanning electron microscope (SEM), while the composition was examined by energy-dispersive (EDX) and X-ray fluorescence (XRF) spectroscopy. The results show that there are significant differences depending on the laser applied and whether the surface is glazed or not. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Laser intra-cavity technique1 has been used sucessfully for the detection of traces of atomic and molecular species (for further references see refs. 2 and 3). For this purpose a broad band flash lamp pumped dye lasers were mainly used. Gas lasers were introduced only on three occasions: a CO laser to detect NO4 and to determine the absolute densities of the individual vibrational levels of CO produced from the reaction between O and CS5 and a He-Ne laser to detect traces of cobalt in the solution2.

In order to obtain short tail-free output laser pulses from a TEA CO2 laser, parametric study of the laser operation with CO2/H2 and CO2/He binary gas mixtures containing high CO2 concentrations was carried out. A small scale UV preionized short delay time TEA CO2 laser was employed. In terms of the maximum extractable output pulse energy and power, the more conventional CO2/He gas mixture was found to be inferior in comparison with the CO2/H2 mixture proposed here.

The design and performance of a small cw CO flame laser with a total power output of 5 W is presented. The influence of the flow rates of the reactants and additives to the spectral composition of the laser power output has been studied in detail.