Excimer laser ablation of bone shock wave measurements and crater profiles

Abstract

The use of the Excimer laser for drilling the stapes bone is investigated using an experimental animal bone model. The absolute intensity of shock-wave generation at two laser wavelengths is measured, and the morphology of the resulting craters is described. It is shown that the roughness of the crater floor resulting from Excimer laser ablation is related to the energy fluence per pulse, and that there is an optimum fluence at which craters may be drilled at a reasonable speed and still have a smooth floor. For 193 nm (ArF) and 248 nm (KrF) wavelengths, this optimum fluence lies between 0.4 and 0.5 Jcm−2 per pulse at a pulse repetition rate of 5 Hz. The amplitude of the resulting shock wave generated at these fluences is 25 bar with a bone thickness of 1.1 mm and 60 bar at a bone thickness of 0.5 mm. Therefore, the corresponding pressure gradient is 0.35 barμm−1 bone.