Nanosecond laser pulses efficiently drill holes in metal

Percussion drilling with nanosecond laser-pulse bursts, instead of single nanosecond pulses, has advantages for metal machining, according to researchers from Multiwave Photonics (Maia, Portugal) and TASC (Albuquerque, NM). The bursts, with a wavelength of 1064 nm, contain up to 14 pulses and repetition frequencies of tens of megahertz per burst. The individual pulsewidths can be varied between 10 and 200 ns; the bursts can occur one at a time or be emitted at up to 500 kHz rates.

The light source, a master-oscillator power-amplifier fiber laser, can be externally triggered and has 12 kW peak power. Each effective pulse can contain controllable multipulse bursts as a result of modulating the laser-diode pump; this is referred to as dynamic pulsing. A 25-µm-thick stainless-steel sheet was chosen as the drilling material. As the number of pulses per burst was increased, the number of bursts required to drill through the sheet dropped—for example, from 35 bursts with single pulses down to 4 bursts with each divided into 10 pulses. The edges of the holes resembled those produced by a very high-repetition-rate modelocked laser.

Contact Sami T. Hendow at [email protected].