High temperature pulsed photoacoustic studies of solids

A noncontact laser system has been designed which utilizes a pulsed photoacoustic source and interferometric detection to allow the absolute velocity of surface waves to be determined accurately at temperatures up to 1000°C. Studies were carried out on aluminum to check the constancy of the calibration with changing temperature before undertaking the (001) plane of silicon. Data are presented for both at temperatures up to 800°C. Measurements of the velocity anisotropy at room temperature on the (001) crystalline face of Si confirm the quoted 1% accuracy and suggest a confirmation of the frequency dependence of the generation efficiency of the various surface waves. Systems such as this could prove useful in materials characterization at elevated temperatures