Measurement of Linear Thermal Expansion Coefficient using Coherent Gradient Sensing

Determination of coefficient of thermal expansion (CTE) of metallic bar using coherent gradient sensing (CGS) is reported in this paper. Collimated light interrogated one end of the specimen/sample kept in a furnace. The light which is reflected from the sample is diverted towards the CGS interferometer using the beam splitter (BS). The set-up is arranged such that, the horizontal fringes due to collimation is achieved. Dimensional variation in the specimen is correlated with the size, shape and orientation of the shear fringes. The change in fringe orientation has been used to estimate CTE.