2aPA2. Velocity measurements in molten materials with the use of laser-generated ultrasound.

Session: Tuesday Morning, December 3

Time: 8:20

Abstract:

The temperature dependence of the longitudinal ultrasonic velocity in solid and molten materials was measured by using laser-generated ultrasound. A Q-switched Nd--YAG laser was used for the generation of the ultrasound source. A diode-pumped cw laser or a long-pulse Nd:YAG laser probed the sample, and then the scattered light from the sample was collected into a multimode optical fiber. The light from the fiber was introduced to a Fabry--Perot interferometer to detect the ultrasonic motion. The velocities of solid materials were compared with those by a conventional pulse-echo method at room temperature. These results were in agreement within 0.1%. A transparent cell was used as a container for molten samples. Thus the ultrasound was generated at the boundary between the sample and the container, and detected at the opposite boundary through the cell. The velocities were measured up to 1000 (degrees)C, which was limited by the furnace.