A laser flash method for measuring thermal diffusivity in the direction parallel or perpendicular to the sample surface of films has been developed. On measurement of parallel direction of a sample, a pulsed laser beam which has narrow line-shaped cross section is flashed onto the front surface of the sample. The temperature response at the back surface at a certain distance away from the line-shaped illuminated area of a laser beam is measured by the infrareddetector and the thermal diffusivity value can be determined by comparing measured temperatureresponse curve with theoretical one.
On the other hand, the measurement of thermal diffusivity in the direction perpendicular to the sample surface of a film, a pulsed laser beam whose diameter is about 10mm, is flashed onto the front surface of the sample. The temperature response at the back surface is measured by the infrared detector. The thermal diffusivity value can be determined by comparing with the theoretical solution including a pulse duration. The usefulness of the present method has been demonstrated by measuring successfully thermal diffusivities of metallic foil samples of platinum (25μm), copper (18μm), SUS304 stainless steel (50μm) and nickel (130μm).
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