Development of a low-temperature laser interferometric dilatometer using a cryogenic refrigerator

A low-temperature laser interferometric dilatometer using a liquid-helium-free cryo- genic refrigerator was developed for the absolute measurement of a linear thermal expansion coefficient with high accuracy. To evaluate the performance of the laser interferometric dilatometer, measure-ments were carried out on a high-purity single crystal of silicon over the temperature range 10^320 K. The measured value of the expansion coefficient was also compared with the recommended value by CODATA. The present result was in good agreement with the recommended value below room temperature, and the deviation from the recommended value was less than0:01 10 ˇ6 K ˇ1 .