Numerical and experimental study on the effect of the pulse format in laser drilling

Numerical and experimental study for pulsed laser drilling is carried out to enhance the understanding of the influence of the pulse format on drilling performance. The mathematical model used in this study simulates major laser-material interaction physics such as heat transfer, vaporization, fluid flow, and multiple reflections. Cooling and solidification phenomena between successive laser pulses are also modeled to consider the pulsed laser process. A modulated beam with a short pulse and high peak power shows a shorter hole penetration time than a conventional pulsed laser under same average power, and it produces the thinnest recast layer by creating a vaporization dominated process. The least tapered hole is also obtained when using the modulated beam. Experiments carried out to validate the model show an improvement in drilling performance for the modulated laser beam as well. It is found that the results of numerical simulation predict well experimental observations.