Dynamics of Ablation Plume of Titanium Target under Femtosecond Laser Exposure

Time and spatial-resolved interferometric technique for continuous registration of motion of titanium sample surface in the picosecond range induced by femtosecond laser pulses of various fluence was used. A qualitative difference in the dynamics of ablation plume expansion was found in case of spallation and phase explosion regimes. The temporal delay of the ejection onset of the excited material surface in a form of a vapor–droplet mixture depending on laser fluence is determined, and the value of the phase explosion threshold is estimated.