Quantitative evaluation of single-shot laser ablated craters using an atomic force microscope. (a) Three-dimensional AFM images of single-shot craters ablated in vacuum with three different laser pulse energies, , 18.8, and 30.0 μJ corresponding to laser fluences of , 17.9, and , respectively. The diameter of the craters increases with laser energy. (b) Center-line profiles of the ablated craters. The crater diameter and the crater depth were measured from data similar to the profiles presented here. The diameter is taken as the distance across the highest points of the rim and the ablation depth is measured from the surface to the bottom of the crater as illustrated in the graph. Note that the scale in the lateral direction is 10 times larger than in the direction normal to the target surface.
The single-shot ablation threshold measurements of borosilicate glass with laser pulses of and . The squared diameter of the ablated areas is plotted as a function of the laser fluence . The slope of the linear fit [Eq. (6)] yields the beam radius at the surface, , and the extrapolation to zero provides the single-shot ablation threshold .
The multishot ablation threshold measurements of borosilicate glass with laser pulses of and . The plots present the logarithmic dependence of the ablation rate on the laser fluence . The slope of the linear fit [Eq. (10)] can be interpreted as the effective optical penetration depth . The extrapolation to zero provides the multishot ablation threshold .
The volume of the ablated craters (a) as a function of the average laser fluence in air and (b) in vacuum and (c) as a function of the squared logarithm of the laser fluence.
The right axis of the plot shows the ablation volume per unit input energy . The left axis of the plot shows the ablation efficiency , described in Eq. (12) in terms of the ratio of the energy required to heat the ablation volume to the melting point to the incident pulse energy. Note that the left and right axes are proportional.
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