Determination of the linear thermal expansion coefficient of long metallic bars by Murty shearing interferometer

Abstract

The dimensional changes produced in materials by temperature variations are generally very small. Hence, sensitive techniques for investigating them are required. A simple optical technique is reported for determining the expansion coefficient of long metallic bars. This newly developed method is based on plane wavefront shearing interferometry, which produces quick and fairly accurate results. The thermal expansion of an object introduces defocusing in the optical system. For calculating this focusing error or the linear thermal expansion the wave aberration function and the wave theory of aberrations have been used.