Abstract
Laser drilling is widely used in manufacturing vias on printed wiring boards. For that purpose, instead of an ordinary Gaussian beam, a flat-top beam is required at an object surface. We propose an optimization method of the beam shape that uses the Fourier Transform of the complex amplitude distribution at an object surface. We use components having space frequency lower than that related to the lens radius to optimize the beam shape so that the optimized beam shape is realized by an actual lens. The method is confirmed numerically using a laser drilling system and the result shows that the optimization method is effective.
