Now researchers from Heriot-Watt University, Liverpool University of Liverpool and GSI Lumonics Ltd. of Rugby have shown that the light from a CO 2 laser can improve the fiber's laser damage threshold to the point that it can deliver the high peak powers necessary for percussion drilling. The fiber delivery of high-energy laser pulses would be a boon to laser machining. Researchers have demonstrated that treating fiber with a CO 2 laser improves its damage threshold. It also allows a single laser to be easily multiplexed between two or more machines. Percussion drilling, in which multiple pulses of laser energy punch holes in the part, is more efficient than trepan drilling, in which the beam cuts out a hole like a saw.
Percussion drilling requires higher peak power pulses, however.
Because optical fiber always has imperfections on the polished ends, these higher powers damage the fiber very quickly, making it unusable. Basing their work on findings that CO 2 laser treatment improves the damage threshold for nanosecond pulses, the researchers examined the suitability of the treatment for the micro- to millisecond pulses needed for percussion drilling. Fiber At Work Treatment with as little as 1 W of laser power increased the damage threshold by more than an order of magnitude. This heats the fiber tip and smooths the scratches and pits that remain from the cleaving and polishing process. Hand said that the treatment improves the fiber's damage threshold to that of commercially polished fused silica.