Caterina Gaudiuso
Università degli Studi di Bari, Italy
Title: Burst features influence on incubation effect during irradiation of stainless steel with burst of picosecond delayed fs laser pulses
Biography
Biography: Caterina Gaudiuso
Abstract
In this work, we report on an experimental study of the incubation effect during the irradiation of stainless steel with bursts of 650fs laser pulses at 1030nm. A series of birefringent crystals was used to split the pristine 650fs pulses into bursts of up to 32sub-pulses with time separations of 1.5ps and 3ps. Th e number of selected bursts was varied between 50 and 1600. In order to highlight the infl uence of the burst features on laser BM processing, the threshold fl uence was measured for each combination of the number of sub-pulses and time delays within the burst. Th e threshold fl uence in NPM was measured as well, to provide a comparison between the two processing modes. In BM, we found as many values of threshold fl uence as the combinations of the number of bursts and of sub-pulses constituting the bursts set to give the same total number of impinging sub-pulses, while in NPM the threshold fluence has a unique value, once the number of impinging pulses is fixed. Therefore, a dependence of the incubation coeffi cient with the burst features was hypothesized and experimentally investigated by assuming the incubation factor as a burst feature dependent coeffi cient. It was found that incubation effect is higher in BM than NPM and that it decreases with the number of sub-pulses n and for shorter time delays within the burst. Th e Two Temperature Model (TTM) has been adapted to the irradiation with single bursts of up to 4sub-pulses to interpret the experimental results.