Micro-hole drilling by tightly focused vector beams

We demonstrated that azimuthally polarized beams offer high-speed laser micro-hole drilling compared with radially and linearly polarized beams under a tight focusing condition. The speed was evaluated by piercing time by vector beams for several objective lenses with different numerical apertures (NAs). As a result, in the case of NA 0.63, the piercing time of an azimuthally polarized beam was 2.4 to 3.2 times shorter than that of a linearly polarized beam for all materials tested. Surprisingly, for NA 0.85, the difference is expanded to about 7.7 times for copper. This indicates that the number of reflections on the side wall of the hole played a significant role to give rise to the difference in the piercing time, depending on the polarization of the light beam.