Determination of material thermal properties using photoacoustic signals detected by a transparent transducer

We demonstrated a new simultaneous determination technique for the thermal diffusivity and the thermal conductivity of a material using photoacoustic (PA) signals detected by a transparent transducer. The samples were illuminated by a pump beam directly or through the transducer, and these two kinds of PA signals were analyzed. It was shown theoretically that we cannot ignore the two effects of small optical absorption of the transducer and the thermal resistance between the sample and the transducer upon detection of PA signals from the viewpoint of quantitative evaluation. The thermal resistance was provided by a small air gap layer. The thermal properties of Si, InP and Ta were determined by this technique and these measured values were in good agreement with those in the literature.