Ultrasonic velocity measurements in molten materials with the use of laser-generated ultrasound

摘要

A novel approach for measurements of sound velocity at high temperatures in solid and molten materials is presented. The sample is contained by a transparent fused quartz cell, through which the laser-generated ultrasound is probed by an optical method. A Michelson-type interferometer is adopted for the faithful detection of the ultrasonic waveforms. The interferometer is combined with a phase conjugator, which converts a scattered beam from the sample into a well collimated beam, thus the ultrasound on a diffusing surface is easily detected at a distance. The temperature dependences of the longitudinal velocity in Sn and Ge have been obtained. The uncertainties in the velocity measurement for the Sn sample have been estimated to be 0.34% and 0.48% in the solid and molten phases, respectively.