Abstract
A new method is described for measuring the thermal expansion coefficient of materials which are available in shapes having a small cross section. In it the displacement of a rolling ball slide is measured using a laser interferometer. The advantage of the apparatus is that a fine finish on the specimen is not required, and even a warped specimen can be measured by holding it under suitable tension. The expansion coefficients of ordinary spring materials have been determined with an accuracy of better than +or-1% at 95% confidence limit.