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Proceedings Paper

Micromachining with tailored nanosecond pulses
Author(s): Hans Herfurth; Rahul Patwa; Tim Lauterborn; Stefan Heinemann; Henrikki Pantsar
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Paper Abstract

Fiber lasers in MOPA configuration are a very flexible tool for micromachining applications since they allow to independently adjust the pulse parameters such as pulse duration, repetition rates and pulse energy while maintaining a constant beam quality. The developed fiber laser provides an average power of 11 W and maximum pulse energy of 0.5 mJ for a wide range of pulse parameters at diffraction limited beam quality. Its pulse duration and repetition rate are continuously adjustable from 10 ns to cw and from 10kHz to 1MHz respectively. Ablation experiments were carried out on stainless steel, nickel and silicon with the goal of optimizing removal rates or surface finish using nanosecond pulses of different parameters. Maximum removal rates are achieved on all three materials using relatively similar pulse parameters. For silicon, pulse duration of 320ns at 100kHz and 45mJ resulted in optimum removal. In single shot experiments on silicon a significant influence of the pulse duration was found with a distinct optimum for removal rate and surface finish. The optimum intensity at the work piece is in the range of 35MW/cm2 to 70MW/cm2. Lower values are below the ablation threshold, while the plasma shielding effect limits considerable increases in removal rates for intensities exceeding 70MW/cm 2.

Paper Details

Date Published: 30 October 2007
PDF: 8 pages
Proc. SPIE 6796, Photonics North 2007, 67961G (30 October 2007); doi: 10.1117/12.778742
Show Author Affiliations
Hans Herfurth, Fraunhofer USA (United States)
Rahul Patwa, Fraunhofer USA (United States)
Tim Lauterborn, Fraunhofer USA (United States)
Stefan Heinemann, Fraunhofer USA (United States)
Henrikki Pantsar, VTT, Technical Research Ctr. of Finland (Finland)

Published in SPIE Proceedings Vol. 6796:
Photonics North 2007
John Armitage, Editor(s)

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