In this paper, the influence of the pulse duration on the ablation threshold and the incubation coefficient was investigated for three different types of materials: metal (copper), semiconductor (silicon) and biopolymer (gelatin). Ablation threshold values and the incubation coefficients have been measured for multiple Ti:sapphire laser pulses (3 to 1000 pulses) and for four different pulse durations (10, 30, 250 and 550 fs). The ablation threshold fluence was determined by extrapolation of curves from squared crater diameter versus fluence plots. For copper and silicon, the experiments were conducted in vacuum and for gelatin in air. For all materials, the ablation threshold fluence increases with the pulse duration. For copper, the threshold increases as s 0.05 , for silicon as s 0.12 and for gelatin as s 0.22 . By extrapolating the curves of the threshold fluence versus number of pulses, the single-shot threshold fluence was determined for each sample. For 30 fs pulses, the singleshot threshold fluences were found to be 0.79, 0.35, and 0.99 J/cm 2 and the incubation coefficients were found to be 0.75, 0.83 and 0.68 for copper, silicon and gelatin, respectively.

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Human skin contains various types of native fluorophores and absorbers with unique absorption and emission spectra, different quantum efficiency, concentration and spatial distribution within the skin. Autofluorescence spectroscopy is applied as diagnostic tool for cutaneous tumor detection that increases the importance of evaluation of natural existing fluorophores and unification of data for given class of pathologies. In the current study, several excitation sources in the region 337-405 nm are applied, to achieve information about typical autofluorescent properties of normal human skin.