Regensburg 2019 – scientific programme

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DS: Fachverband Dünne Schichten

DS 7: Optical Analysis of Thin Films II (Reflection, Ellipsometry, Raman, IR-DUV Spectroscopy, ...

DS 7.2: Talk

Monday, April 1, 2019, 15:15–15:30, H32

Structural Color Sensors: Tracking the Thermal History of Materials — •Henning Galinski¹, Volker Schnabel¹, Max Döbeli², and Ralph Spolenak¹ — ¹Laboratory for Nanometallurgy, Department of Materials, ETH Zurich Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland — ²Ion Beam Physics, ETH Zurich, Otto-Stern-Weg 5, 8093 Zurich, Switzerland

The engineering of non-destructive, low footprint optical sensors has attracted significant interest in research in recent years. Such devices can enable real-time and spatiotemporal tracking of materials properties even in secluded applications, such as offshore wind turbines, or extreme environments, as found in thermal solar collectors. Here, we demonstrate a novel thermal sensor based on structural color that provides direct optical feedback of materials properties such as hardness, wear and resistivity [1]. The sensor can be used at high temperatures (1000 °C) and allows the continuous detection of changes in refractive index larger than 1%. The monitoring concept relies on a lossy Gires-Tournois interferometer configuration using thermally induced detuning of a highly absorbing state in the optical spectrum as sensor feedback. The displacement of the absorbing state is directly proportional to thermally induced changes in hardness and resistivity in the material. Using the specific case of TiAlN coatings we show that such detuning is due to a symmetry-breaking structural phase transition, which is accompanied by the formation of saturated structural colors.

[1] V. Schnabel, R. Spolenak, M. Döbeli, H. Galinski, Advanced Optical Materials 2018, 6, 1800656.