Crater shapes and plasma plume expansion in the interaction
of sharply focused laser beams (10 μm waist diameter, 60
fs–6 ns pulse duration) with metals in air at atmospheric
pressure were studied. Laser ablation efficiencies and rates
of plasma expansion were determined. The best ablation efficiency
was observed with femtosecond laser pulses. It was found that
for nanosecond pulses, the laser beam absorption, its scattering,
and its reflection in plasma were the limiting factors for
efficient laser ablation and precise material sampling with
sharply focused laser beams. The experimental results obtained
were analyzed with relation to different theoretical models
of laser ablation.
Controlling the carrier-envelope phase of few-cycle focused laser beams with a dispersive beam expander
