Excimer laser ablation of sintered hydroxyapatite

The ablation treatment of a sintered hydroxyapatite (Ca10(PO4)6(OH)2) sample has been studied by irradiating the excimer laser in air at one atmosphere for the micro machining treatment. Three different excimer lasers of ArF, KrF and XeF with wavelengths of 193 nm, 248 nm and 351 nm, respectively were used to examine the effect of the wavelength on the ablation rate and the surface morphology of the ablated area. Photochemical ablation of sintered hydroxyapatite is possible with ArF and KrF excimer lasers and the flat bottom shape of an ablated hole with sharp edge can be obtained. On the contrary, thermal ablation occurred in the case of XeF laser due to a long wavelength, and the ablation rate was much larger than those in the case of ArF and KrF lasers, though the ablated surface was rough and not flat. Threshold values of laser fluence for ablation were about 0.8, 1.5 and 6 J/cm2 for ArF, KrF and XeF, respectively.