Measurement of Thermal Expansion by Moiré Interferometry

Abstract

In this paper we present a simple optical method, used the moire phenomenon, which is a straightforward method for contactless non-destructive metrological measurements, used to measure the thermal expansion and shrinkage of materials. This method comes in complement with the other existing methods. Indeed, at the time of measurement of expansion or the expansion coefficients, as well as, the other thermal parameters, there is the risk, that the result of measurement is sullied by errors, which are due to the measurement system. The method proposed in this paper, is based on an optical system, which uses the moire techniques as method of control, which can currently detect nano-movement, who can reach 40 10-9 m. This value can be improved, because the optical system allows it. In this arrangement the link between the specimen to be analyzed and the system of measurement is made by optical way, which decreases the influence of the system on the result. The method proposed, allows a continuous assessment in real time, and gives results with good accuracy, owing to the fact that the optical system is not affected by the heat of furnace, which also offers the possibilities of controlling a material at the highest temperature with precision measurements.