  A two-dimensional axisymmetric transient laser drilling model is used to
analyze the effects of laser beam diameter and laser pulse duration on the
laser drilling process. The model includes conduction and convection heat
transfer, melting, solidification and vaporization, as well as material removal
resulting from the vaporization and melt ejection. The validated model is
applied to study the effects of laser beam size and pulse duration on the
geometry of the drilled hole. It is found that the ablation effect decrease
with the increasing beam diameter due to the effect of increased vaporization
rate, and deeper hole is observed for the larger pulse width due to the higher
thermal ablation efficiency.
