Improving Speed and Quality of Single-Pulse Laser Drilling in Stainless Steel using Rectangularly Shaped Microsecond Pulses

Single-pulse laser drilling of stainless steel foils was investigated using temporally rectangular microsecond pulses generated by an acousto-optically modulated continuous-wave laser beam. The resulting pulses exhibit powers of up to 1400 W, variable pulse durations ranging from 1 s to 30 s, and short rise and fall times of about 250 ns. Drilling speeds in excess of 30 m/s and reproducible borehole diameters in the double-digit micrometer range were achieved. This results in a high throughput capability as demonstrated by producing more than 6000 through-holes per second in up to 300 m thick foils of stainless steel.