HIGH-TEMPERATURE PULSED PHOTOACOUSTIC STUDIES OF SURFACE-WAVES ON SOLIDS

A noncontact laser system has been designed that employs a pulsed phot oacoustic source and an interferometric detector for the measurement o f absolute velocity of surface waves. This can be achieved accurately at high temperatures without the need for thermal expansion correction s. Studies have been carried out on polycrystalline aluminum and singl e-crystal silicon and results have been presented for both at temperat ures up to 800 degrees C. The angular dependence of surface wave veloc ities for propagation in the (001) plane of silicon has also been inve stigated, and has confirmed the system's 0.5% room temperature accurac y.