Measurement of thermal expansion coefficients of materials based on Nd:YVO4laser feedback systems

Abstract

The noncooperative and high sensitivity optical displacement measurement technology is very relevant to the study and the determination of high-precision thermal expansion coefficients (TECs) of materials. This paper describes a measurement technology based on Nd:YVO4 laser feedback systems, which can realize fully non- contact measurement of many kinds of materials with surface reflectivity greater than 10-5. A muffle furnace is designed with two coaxial holes opened on the opposite furnace walls. This length determination technique is based on the frequency-shifted optical feedback effects and the heterodyne phase measurement technique. For validation, the samples are determined in the temperature range 298 to 748K, confirming high sensitivity non- contact measurement of the materials and demonstrating TEC-measurement capabilities with uncertainties in the range of 10-7 or less.