CHARACTERIZATION OF HYDROXYAPATITE LASER-ABLATION PLUMES BY FAST INTENSIFIED CCD IMAGING

ArF excimer laser pulses (193 nm, 20 ns, 150 mJ) have been focused on a hydroxyapatite (HA) target in similar conditions to those normally u sed for thin film deposition. Fast intensified CCD images of HA laser ablation plumes have been taken in vacuum and under different water va por pressures ranging from 0.01 mbar to 1 mbar. Images of HA ablation in vacuum have shown a plume freely expanding at a constant velocity o f 2.3 X 10(6) cm/s. HA ablation under a water vapor pressure of 0.01 m bar has revealed an expansion behavior very similar to that of ablatio n in vacuum. Images taken under a water vapor pressure of 0.1 mbar hav e shown the formation of a shock structure in the plume. Finally, HA a blation under a water vapor pressure of 1 mbar has revealed the develo pment of some irregularities in the shape of the plume.