Photothermal bending of a layered sample in plate form

In this paper, we report a photothermal effect (drum effect) of the layered platelike sample. Irradiation of chopped laser light on the clamped plate produces flexural vibration from the thermoelastic bending if the plate is thin. The characteristics of thermoelastic bending of the layered plate are theoretically examined on the basis of the temperature moment caused by thermal wave propagation. It is shown that the layered structure of the platelike sample can be obtained from the amplitude and phase signals of the vibration. Hence this effect will be useful as a photothermal inspection technique for the layered plate. A comparison with the conventional photothermal signal is also presented for a layered sample.