Abstract
Micro-holes of 100 to 300 µm were drilled through on cemented tungsten carbide plates of 0.5 and 1 mm thick by ultrafast laser pulses (150 fs at 800 nm, 1 kHz repetition rate) via a galvano-scanner with an 80 mm focal length lens. Effects of scan speed and polarization were examined. It is found that circularly polarized beam results in regular holes while linearly polarized beam produces distortions on their shape. Scan speed affects the shape of drilled hole, too. Laser induced periodic surface structures (LIPSS), which are formed at a period of 300 nm and oriented perpendicular to laser incident axis, were found on whole side of the hole drilled by circular polarized light. The formation of LIPSS by linearly polarized beam was dependent on the relative angle between the incident plane on the wall surface and the polarization direction.
