Erlangen 2022 – scientific programme
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A: Fachverband Atomphysik
A 30: Precision Measurements and Metrology II (joint session Q/A)
A 30.15: Poster
Thursday, March 17, 2022, 16:30–18:30, P
Measuring small coefficients of thermal expansion with Fabry-Perot resonators — •Nina Meyer, Maryam Ghazi Zahedi, Tobias Ohlendorf, Uwe Sterr, and Thomas Legero — Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany
Materials with small coefficients of thermal expansions (CTEs) are needed for industrial and scientific applications as in extreme-ultraviolet lithography, in telescopes or ultra-stable resonators [1]. Such materials, like Zerodur and Corning ULE glass, show a very small CTE of about 10−8 K−1, with zero crossing near room temperature. CTE measurements based on two-beam Michelson interferometers for measuring length have reached 10−9 K−1 uncertainties [2].
In this poster, we present a multiple-beam approach based on a Fabry-Perot resonator, consisting of a test-material spacer and two optically contacted reflecting endcaps in a temperature-controlled vacuum chamber.
We discuss a refined uncertainty budget taking the temperature homogeneity of the spacer and the impact of the CTE mismatch between the end caps and the spacer into account [3]. This allows us to determine the CTE with uncertainties in the range of 10−9 K−1.
[1] F. Riehle, Meas. Sci. Technol. 9, 1042−1048 (1998).
[2] R. Schödel, Meas. Sci. Technol. 19, 084003 (2008).
[3] T. Legero et al., J. Opt. Soc. Am. B 27, 914-919 (2010).