Interferometric study of the laser-induced melting stage of an absorbing glass

We study the processes of glass heating and melting by absorption of laser radiation using profilometry in reflected light and interferometric real time analysis. The sample irradiation is obtained by an argon ion laser and the interference pattern is generated by a He-Ne laser or by another argon ion laser. In the reflected beam we observe a change of the ring pattern caused by the increasing of pumping power. Above a certain level an additional ring pattern appears. We study the dependence of the structure of the ring patterns as function of the power of the pumping laser beam. From the diffraction pattern and the interference pattern given by a wedge shearing interferometer we estimate the shape and dimension of the mound and respectively the dimple generated for different pumping powers.