A practical measurement system for the accurate determination of linear thermal expansion coefficients

An accurate and versatile system for the measurement of linear thermal expansion coefficient is described. The system consists of a double-path optical heterodyne laser interferometer and a parallel spring strip supporting system which provides both versatility and accuracy of measurement. The interferometer has a resolution of 1 nm and the parallel strip supporting system is used to accommodate various shapes and dimensions of specimens to be measured. From the measurements of twelve industrial materials including two standard reference materials at room temperatures, the measurement accuracy is estimated to be within 3 to 7*10 -8 K -1 on material having corresponding expansion coefficients of between -1 and 23*10 -6 K -1 .