Photoacoustic detection of microcracks induced in glass by focused laser pulses

In our work, the degradation of BK7 glass originated by multipulse damage by focused light inside of the bulk are measured using photoacoustic detection. The degradation is determined from the amplitudes of the first photoacoustic peak signals, working at the single-pulse threshold. With this technique it is easy to determine the most appropriate laser parameters for microcrack formation in three-dimensional engraving. In resume, we have described a technique which can be used to detect degradation in glasses, in particular tests were made in BK7 glasses with a pulsed Nd:YAG laser (at 532 nm, t≈20 s).