On the selection of the experimental parameters in a Thermal-Wave-Resonator-Cavity (TWRC) configuration

The paper investigates the influence of the most important experimental parameters on the behaviour of the phase of the back-photopyroelectric signal, in a thermal-wave-resonator-cavity. The linear behaviour of the "phase versus thickness" curve is located in the 2<Labs m /μ m <3 range, being delimited by the thermal impedance at the interfaces of the detection cell in the thermally thin regime, and by the signal/noise ratio, in the thermally thick side. A proper choice of the experimental parameters, together with a small enough thickness variation step (≤1μm) lead to an accuracy of about ±0.3% for the values of thermal diffusivity of liquids.