Experimental setup. (a) Setup for measuring the propulsion distance of the microbead by monitoring the microbead’s position before and after it was hit by the filament of a single laser pulse using the CCD camera. (b) Alternative interaction setup for investigating the longitudinal plasma distribution (the spectral region of the signal measured by this side-localized CCD camera mainly covers 320–430 nm). (c) Alternative interaction setup for observing the distance dependent ablation rate induced by the filament. (When the signal level measured by the photodiode is higher than a predetermined value, a stable hole is created. Also, the number of shots required to create a stable hole that is inversely proportional to the ablation rate is counted by a homemade computer program.)
(a) Measured propelled distances of the micro glass beads (the open squares) as a function of the initial bead position in reference to the focal lens and the measured distribution of the normalized fluorescence intensity of the filament (the open triangles). (b) Simulated single-shot ablation volume of the aluminum sample as a function of the initial aluminum foil position in reference to the focal lens (the open squares) and the simulated longitudinal distribution of the linear plasma density (the solid line). (c) The experimentally determined number of pulses required to drill a through-hole on the thick aluminum foil when the foil is placed at different positions relative to the focal lens along the laser propagation direction.
The calculated traverse laser fluence distributions of the laser filament and the corresponding ablation depths at 108 and 111 cm from the focal lens.
The simulated ablation volume and the corresponding on-axis plasma density. The laser parameters are 1 mm in beam diameter and the pulse energy is 1 mJ/pulse.
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