Comparison of Characteristics of Drilled Holes Using a Gaussian Beam and a Flat-top Beam in Laser Perforation

In the field of microfabrication, laser processing is a very important key technology. It is widely used in etching, perforation, microchannel preparation, etc. Most of the beams commonly used for laser drilling have the transverse distribution with a Gaussian shape, but such beam energy distribution will increase the thermal effects in the processed area, reduce the accuracy and efficiency of machining, and bring about some problems of the taper angle and cracks of drilled holes. Since some useful approaches have been invented to change the spatial energy distribution of a laser beam, we begin to explore whether the quality of laser-assisted perforation can be improved by using a spatially-shaped laser. At present, the flat-top laser with high beam quality is utilized in the area of inertial confinement fusion and laser biomedicine. In this paper, we select aluminum as the substrate material in the numerical simulation and use the algorithm of constrained interpolation profile to simulate the variation of density, temperature, and pressure during the laser drilling process under the conditions of two spatial distribution shapes of nanosecond pulsed lasers with the same pulse energy. The processing quality and efficiency have been compared under two kinds of laser shapes, and the evolution trend of morphology has been finally summarized under different processing conditions. The theoretical results reveal that the laser perforation using a top-flat laser beam should have some special advantages over that using a conventional Gaussian laser beam. So far, there have been few studies on the theoretical investigation of industrial perforation mechanism using lasers with different spatial distribution. This paper might provide a new perspective to optimize the quality of laser perforation in the field of industrial manufacture.