Open AccessCooling rate calibration and mapping of ultra-short pulsed laser modifications in fused silica by Raman and Brillouin spectroscopy
Author(s) -
Michael Bergler,
Kristian Cvecek,
Ferdinand Werr,
Martin Brehl,
Dominique de Ligny,
Michael Schmidt
Publication year - 2020
Publication title -
international journal of extreme manufacturing
Language(s) - English
Resource type - Journals
eISSN - 2631-8644
pISSN - 2631-7990
DOI - 10.1088/2631-7990/ab9583
Subject(s) - brillouin zone , raman spectroscopy , brillouin scattering , materials science , raman scattering , laser , optics , brillouin spectroscopy , residual stress , raman cooling , rayleigh scattering , calibration , analytical chemistry (journal) , molecular physics , x ray raman scattering , chemistry , composite material , physics , chromatography , quantum mechanics
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 ( T f ) 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.