Processing of metals with ps-laser pulses in the range between 10ps and 100ps

Abstract

The potential of pulsed laser system in the range of 10ps to 100ps pulse duration for material processing has been further investigated. In detail the dependency of the volume ablation rate, penetration depth and threshold fluence on the pulse duration and number of pulses applied to the material will be discussed. The experimental results show that in the case of copper and steel, better results in quality and efficiency of the ablated material are achieved with shorter pulse durations.

Influence of the Pulse Duration onto the Material Removal Rate and Machining Quality for Different Types of Steel

“…The pulse duration of these systems is in the range of several 10 ps, (Pierrot et al (2011), Kanzelmeyer et al (2011)). For metals the ablation efficiency significantly drops by about a factor of 5 when the pulse duration is raised from 10 ps to 50 ps as shown by Schmid et al (2011) andJäggi et al (2011), for non metals this drop is less pronounced but still present as shown by Neuenschwander et al (2011).…”

“…Due to incubation effects the threshold fluence also strongly depends on the number of pulses applied, which is described for metals by Schmid et al (2011), Neuenschwander et al (2012, Jee et al (1988) and Mannion et al (2004). Additionally it was found that also the energy penetration depth shows an incubation effect of the same kind.…”

“…For metals and pulses longer than 10 ps the threshold fluence begins to increase as shown by Schmid et al (2011. But beside the threshold fluence also the penetration depth has an influence onto the maximum volume ablation rate.…”

“…Additionally it was found that also the energy penetration depth shows an incubation effect of the same kind. The maximum removal rate may therefore also strongly depend on the number of pulses applied; more details are given in Schmid et al (2011), Neuenschwander et al (2012.…”

Burst mode with ps- and fs-pulses: Influence on the removal rate, surface quality, and heat accumulation

“…that there exists a maximum removal rate per average power 1,2 . This maximum depends on the pulse duration 3,4,5,6 whereas shorter pulses lead to higher removal rates. As working at this maximum point usually demands moderate fluences (typically in the range of 1 J/cm 2 or less) multi -spot processing or high speed scanning represent potential technologies to work at high average powers.…”