Bergler M, Cvecek K, Werr F, Brehl M, De Ligny D, Schmidt M. 2020. Cooling rate calibration and mapping of ultra-short pulsed laser modifications in fused silica by Raman and Brillouin spectroscopy. Int. J. Extrem. Manuf. 2, 035001.
Citation:
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Bergler M, Cvecek K, Werr F, Brehl M, De Ligny D, Schmidt M. 2020. Cooling rate calibration and mapping of ultra-short pulsed laser modifications in fused silica by Raman and Brillouin spectroscopy. Int. J. Extrem. Manuf. 2, 035001.
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Cooling rate calibration and mapping of ultra-short pulsed laser modifications in fused silica by Raman and Brillouin spectroscopy
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Michael Bergler1,2,3
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Kristian Cvecek1,3
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Ferdinand Werr2
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Martin Brehl2
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Dominique De Ligny2
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Michael Schmidt1,3
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More Information
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1 Friedrich-Alexander-Universit¨at Erlangen-Nürnberg, Institute of Photonic Technologies, Erlangen,
Germany
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2 Friedrich-Alexander-Universit¨at Erlangen-Nürnberg, Institute of Glass and Ceramics, Erlangen,
Germany
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3 Friedrich-Alexander-Universit¨at Erlangen-Nürnberg, SAOT – Erlangen Graduate School in Advanced
Optical Technologies, Erlangen, Germany
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Abstract
This paper focuses on the preparation of a new extended set of calibrations of cooling rate (fictive temperature) in fused silica determined by inelastic light scattering and its subsequent use to characterize the local cooling rate distribution in ultra-short pulsed (USP) laser modification. In order to determine the thermal history (e.g. cooling rate and fictive temperature) of fused silica, high-resolution inelastic light-scattering experiments (Raman and Brillouin spectroscopy) were investigated. Calibrations were performed and compared to the existing literature to quantify structural changes due to a change of fictive temperature. Compared to existing calibrations, this paper provides an extension to lower and higher cooling rates. Using this new set of calibrations, we characterized a USP laser modification in fused silica and calculated the local fictive temperature distribution. An equation relating the fictive temperature (Tf ) to cooling rates is given. A maximum cooling rate of 3000 K min−1 in the glass transition region around 1200 °C was deduced from the Raman analysis. The Brillouin observations are sensitive to both the thermal history and the residual stress. By comparing the Raman and Brillouin observations, we extracted the local residual stress distribution with high spatial resolution. For the first time, combined Raman and Brillouin inelastic light scattering experiments show the local distribution of cooling rates and residual stresses (detailed behavior of the glass structure) in the interior and the surrounding of an USP laser modified zone.
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Keywords
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Author Introduction
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Michael Bergler received his B.Sc. and M.Sc. degrees in Nanotechnology from Friedrich-Alexander-Universität Erlangen-Nürnberg (Germany) in 2014 and 2017. He is currently working on his PhD as part of the ‘Ultrashort Pulse Laser Technologies’ group of the Institute of Photonic Technologies (Prof. Dr. Michael Schmidt) and the ‘Research Group Glass’ of the Institute of Glass and Ceramics (Prof. Dr. Dominique de Ligny) of the Friedrich-Alexander-Universität Erlangen-Nürnberg. He is concurrently a doctoral candidate of the SAOT – Erlangen Graduate School of Advanced Optical Technologies.
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Prof. Dr.-Ing. Michael Schmidt holds the chair of the Institute of Photonic Technologies since its founding in 2009 at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU). He received his doctoral degree on the topic “Process control of laser spot welding in electronics production” in 2002. Following his engagement in its executive board, he leads the Bayerisches Laserzentrum GmbH (blz GmbH) as managing director since January 2005. Starting from 2013, he is the coordinator of the Erlangen School in Advanced Optical Technologies (SAOT). Until 2018, he build up a laboratory for Additive Manufacturing with Kazan University (KAI) with the Mega Grant he received in 2014. Within the German research community, he is involved as the president of Wissenschaftliche Gesellschaft Lasertechnik e.V. (WLT), promoting the scientific and professional interests of laser technology. In addition to that, he is involved in several other national and international research groups and committees. His current research interests include laser application from micro- to macroscopic scale within the fields of industrial manufacturing, additive manufacturing and medical engineering.
https://www.lpt.tf.fau.eu/the-institute/head-of-the-institute/
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