MEASUREMENT OF THERMAL-DIFFUSIVITY PARALLEL TO THE SURFACE OF PLATE-LIKE SPECIMEN BY THE LASER-PULSE HEATING METHOD

A new method has been developed to measure the thermal diffusivity par allel to the surface of a platelike specimen using laser pulse heating . A pulsed laser beam which has a circular cross section is irradiated onto the front surface of the specimen. The time dependence of the te mperature response of a circular area on the back surface at a certain distance from the irradiated area is determined using a radiation det ector for which the spatial distribution of sensitivity is experimenta lly determined. The geometry of the apparatus is determined using stan dard specimens the thermal diffusivity of which is known. For isotropi c samples, the values parallel to the surface obtained by the present method agree within 10% with those perpendicular to the surface obtain ed by the conventional pulse heating method. (C) 1996 American Institu te of Physics.