A picosecond laser used in micromachining applications does not create a heat-affected zone.
Available in several power ratings, the Rapid and Super Rapid picosecond lasers ablate any material. Owing to their low average power and pulse energy, these picosecond lasers are configured for micromachining materials with thicknesses of 1 ml or less.
“If someone is looking to do huge cutting in big metal, these tools are not the right solution,” says Chuck Ratermann, president of RPMC (O’Fallon, MO), the exclusive North American distributor of the lasers. “However, the Super Rapid 8-W laser will remove about 1 mm3/min in most metals.”
There are many advantages of picosecond lasers over nanosecond lasers, according to Ratermann. In some instances, nanosecond lasers leave microcracks in glass or ceramic that could induce device failure. Conversely, picosecond lasers do not cause such defects. Ratermann says that the avoidance of a melt-phase during ablation is the underlying reason. Unlike picosecond lasers, use of nanosecond lasers can also result in the presence of burrs requiring postprocessing.
Femtosecond, or 10–15 second, lasers, on the other hand, share the favorable absence of a heat-affected zone with picosecond lasers. However, femotosecond lasers are not cut out for industrial applications owing to their sensitivity to temperature and vibration, Ratermann asserts. “They do really great drilling with no heat-affected zone,” he says. “But the problem is that they are so complex and expensive that you just can’t have them in a factory.”
Designed for industrial use, the picosecond lasers are sealed and thermalized. In addition, control software enables operators to program the number of pulses in a group, as well as delays between pulse groups.