Intercomparison of Interferometric Dilatometers at NRLM and NPL

Abstract

Interferometric dilatometers at the National Research Laboratory of Metrology (NRLM) in Japan and the National Physical Laboratory (NPL) in UK been intercompared by measuring the thermal expansion coefficients of pure polycrystalline silicon, a low expansion ceramic (Miraclon) and fused silica (SRM 739). The dilatometers, two from each laboratory, were intercompared over their respective operating temperature ranges of 250 to 375 K and 290 to 800 K. The results presented in this paper show that the agreement for each material is within the combined uncertainties in the measurement of each thermal coefficient of expansion.