Measurement of thermal expansion coefficients by electronic speckle pattern interferometry at high temperature

Electronic speckle pattern interferometry (ESPI) is a non-contact system using laser and video as tools for measuring strain produced by thermal expansion of objects during heating. It is the generation of moire fringes which result from the electronic subtraction between two speckle patterns. Inconel 601 was studied using ESPI and a color camera was used to sense the laser speckles. The results for the thermal expansion coefficients measured by ESPI compared to those obtained by moire method were almost the same up to 600 °C. Surface oxidation became severe at high temperature so the measurable temperature by the ESPI technique is limited to 1200 °C.