抄録
The purpose of this study is to estimate the shape of ablated crater with sufficient accuracy when the multi-shot of the ultra-short pulse laser are irradiated to glasses. In this analytical model, the complex dielectric function of the Lorentz model is applied, in order to consider that glasses are dielectrics and to evaluate the damage by the laser ablation. Simultaneously, the time evolutions of free electrons density for distinguishing the ablation region and the damage region are calculated, and finally the threshold fluences are able to be computed quantitatively to various laser irradiation conditions. The absorption coefficients and threshold fluences which were obtained by this analysis were applied to the Beer-Lambert law, and it was well in agreement with the crater depth obtained from this analysis. Moreover, the crater shapes over the multi-shot channels in consideration of the laser fluence dependences of the absorption coefficients and the threshold fluences at the first shot were well in agreement with experimental results.
