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Development of a high accuracy laser interferometric dilatometer over the temperature range from 300 K to 1200 K
Sun Jian Ping, Liu Jian Qing, Yang Xin Yuan, Zhang Jin Tao and Duan Yuning

A high accuracy laser interferometric dilatometer with a resolution of less than 1 nm has been developed in the National Institute of Metrology, China. This instrument is based on a single frequency polarized interferometer. The disadvantage of the single frequency procedure is that the zero may drift with time. In order to improve the stability, we developed a procedure to correct the effect of this drift, to ensure the stability of the device within 1 nm. The performance of the new device has been examined by measuring some reference materials. The Standard Reference Material 738 (austenitic stainless steel) from the National Institute of Standard and Technology was measured over the temperature range from 300 K to 770 K. The measured linear Expansion Coefficient agreed with the values referred by NIST of the relative deviation less than 1.7% with the combined standard uncertainty at room temperature of 3.4 × 10-2(k = 2). The silicon sample was measured over the range from 770 K to 1200 K, and the measurement results were in good agreement with the recommended values by the Committee on Data for Science and Technology (CODATA).

Keywords: linear expansion coefficient; single frequency; laser interferometer; SRM738; relative deviation; combined standard deviation.

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