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Analysis of the hole shape evolution in fs-pulse percussion drilling with bursts

: Kämmer, H.; Dreisow, F.; Tünnermann, A.; Nolte, S.


Heisterkamp, A. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XVI. Proceedings : 14-16 February 2016, San Francisco, California, United States
Bellingham, WA: SPIE, 2016 (Proceedings of SPIE 9740)
ISBN: 978-1-62841-975-7
Art. 974012
Conference "Frontiers in Ultrafast Optics - Biomedical, Scientific, and Industrial Applications" <16, 2016, San Francisco/Calif.>
Conference Paper
Fraunhofer IOF ()

We analyze the use of bursts of ultra-short pulses in order to improve drilling efficiency and quality. Silicon is used as a non-transparent model material, in which the behavior of laser percussion drilling with 1030 nm bursts consisting of 200 fs pulses separated by a time delay between 1 ps and 4 ns was investigated. The deep drilling process is directly imaged perpendicular to the drilling direction using a CCD camera and an illumination beam at 1064 nm, where the silicon sample is transparent. The results are compared to drilling without bursts for different pulse energies. The efficiency of the drilling process, hole quality, as well as reproducibility of the hole shape are analyzed.
Pulse separation times within the burst from 1 ps to 8 ps result in deeper holes with a larger silhouette area, however equal or reduced hole quality and reproducibility compared to drilling with individual pulses. In contrast with pulse separation times from 510 ps to 4 ns a quality and reproducibility improvement is visible. For these delay times the achieved depth was equal or higher compared to micromachining without bursts.