Development of a Laser Interferometric Dilatometer for Measurements of Thermal Expansion of Solids in the Temperature Range 300 to 1300 K

Abstract

A laser interferometric dilatometer has been developed for measuring linear thermal expansion coefficients of reference materials for thermal expansion in the temperature range 300 to 1300 K. The dilatometer is based on an optical heterodyne interferometer capable of measuring length change with an uncertainty of 0.6 nm. Linear thermal expansion coefficients of silicon were measured in the temperature range 700 to 1100 K. The performance of the present dilatometer was tested by a comparison between the present data and the data measured with the previous version of the present dilatometer and the data recommended by the Committee on Data for Science and Technology (CODATA). The present data agree well with the recommended values over all the temperature range measured. On the other hand, the present values at lower temperatures are in poor agreement with the previous experimental data. The combined standard uncertainty in the present value at 900 K is estimated to be 1.1×10⁻⁸ K⁻¹.