Ultrafast laser processing with non-diffracting beams for ablation and drilling of opaque materialsThursday (25.06.2020) 09:20 - 09:40 Room 2
Thanks to the unique properties of femtosecond laser pulses, the field of ultrafast laser processing knows a spectacular growth in many applications involving surface and bulk structuring. The precision offered the technique relies on the reduced thermal effects associated with the ultrafast timescales of the laser-matter interaction. In the quest of an increased machining precision and flexibility, non-diffracting (e.g Bessel) laser beams can be advantageous over the usual Gaussian intensity distributions. Formed by a conical modulation of the laser wavefront, these beams present an invariant intensity profile along the propagation direction on significantly longer distances than their Gaussian counterparts. The use of ultrafast laser Bessel beams for high aspect ratio structuring of transparent materials has been very-well studied.
In this report, we study their potentials in precise machining of opaque materials, particularly steel. More precisely, we focus on the use of these beams for ablation and drilling and compare their efficiency to the case of usual Gaussian beams by systematically evaluating the removal rate and the final surface roughness. The comparison is also conducted on the laser pulse energy, duration, repetition rate and overlap. Numerical simulations are also conducted to better understand the differences in processing between the Gaussian-like and Bessel-like laser field distributions. In particular, we underline the self-reconstruction properties of the Bessel beam in presence of particle-like obstructions.
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