Temperature distribution in optical trepanning

Abstract

Optical trepanning provides a drilling mechanism by using an annular beam. This paper investigates the temperature distribution in the workpiece due to pulsed annular laser beams. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting the hole quality than a solid laser beam. Such profiles include half Gaussian with maximum intensities at the inner and outer radii of the annulus, respectively, and full Gaussian with maximum intensity within the annulus. In addition to this spatial beam shaping, the temporal profile of the laser pulse can be shaped to improve the hole quality. The Hankel and Laplace transforms have been used to obtain an analytic solution for the temperature distribution in a semi-infinite workpiece. The effects of the temperature distribution on laser drilling are analyzed to design an efficient drilling process.Optical trepanning provides a drilling mechanism by using an annular beam. This paper investigates the temperature distribution in the workpiece due to pulsed annular laser beams. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting the hole quality than a solid laser beam. Such profiles include half Gaussian with maximum intensities at the inner and outer radii of the annulus, respectively, and full Gaussian with maximum intensity within the annulus. In addition to this spatial beam shaping, the temporal profile of the laser pulse can be shaped to improve the hole quality. The Hankel and Laplace transforms have been used to obtain an analytic solution for the temperature distribution in a semi-infinite workpiece. The effects of the temperature distribution on laser drilling are analyzed to design an efficient drilling process.