Theoretical Study of Morphology of Holes Drilled by a Double-pulsed Laser Train

Laser drilling is widely used in the field of laser processing. In fact, laser-assisted drilling has been achieved for processing a variety of materials. With the development of the microprocessing applications, the quality of laser drilling has become an important factor that cannot be ignored. When the energy of a laser pulse is assumed as a constant, the narrower the pulse width, the higher the peak power. Many studies have demonstrated that the quality of the laser-drilled holes is related to the pulse width, pulse energy, and focused spot size of a laser. In this study, aluminum is selected as the base material on which some special holes have been drilled by using a double-pulse laser train at the wavelength of 532nm. We first numerically simulate two sets of processing results by employing a double-pulsed laser with the total power of 8W and the pulse interval of 30 and 60ns, respectively. Note that the energy is assumed to be the same during the simulation using the constrained interpolation profile (CIP) algorithm. The morphology of drilled holes is numerically simulated with the different proportions of the power for the first and second pulses. To investigate the laser-assisted drilling process, we refer to the variations in density, pressure, and temperature of the above targets. We also undertake the analyses of morphology of processed samples with the different pulse intervals of 30, 60, 150, 210, 300, 450, and 600ns. It can be seen that when the total energy is set to be the same, the hole morphology depends on both the pulse interval and the power ratio of two pulses. Our theoretical research is thought to be of certain guiding significance for the applications of laser processing in the field of industry.