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6401 |
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In-depth chemical stratigraphy and porosity analysis with non-scanning-single-spot optical coherence tomography laser-induced breakdown spectroscopy
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Tristan Oliver Nagy / University of Vienna, Department of Physical Chemistry / LIStrat Industrial Analytics GmbH, Austria Morris Weimerskirch* / University of Vienna, Austria Fabian Kraft/ University of Vienna, Department of Physics & LIStrat GmbH, Austria Ulrich Pacher/ Department of Physical Chemistry, Austria |
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LIBS is a proven method for elemental analysis. It needs little to no sample preparation and relies solely on optical access to the sample. LIBS has therefore been handled as a promising analytic method for layered or structured samples with the potential to replace metallurgic cross-sections followed by optical microscopy or SEM/EDX raster screenings. Due to the strong dependency of the ablation process on changing crater geometries, laser fluence and plasma dynamics (e.g. self-absorption, material dependent optical depths, reflection coefficients, scattering processes, etc.), attributing an absolute depth to the number of laser pulses and hence of the position of origin of a chemical composition signal applied to the sample is not trivial. In this work, we show absolute depth recognition based on single-spot, non-scanning optical coherence tomography on LIBS craters produced with an in-situ LIBS/OCT analyser. Also we verify these results with the use of ex-situ (electron-microscopic and computer tomographic) techniques. We discuss it's potential application for density and hence porosity probing in LIBS-stratigraphy for fast QC/QA in the production line. This enables the quantification of key properties in porous and structured samples like thermal-barrier coatings (TBCs) , used in the hot section of state-of-the-art aircraft jet engines. |