Photoacoustic detection of microcracks of thin film head alumina using Nd:YAG laser irradiation

Acoustic wave generation during Nd:YAG laser irradiation on thin film head alumina is studied. It is found that with proper selection of laser parameters, the acoustic waveforms observed are completely different for pristine head and head with preexisting microcracks. It has potential applications of thin-film heads and head wafers.