Emissivity measurements by sine wave thermal modulation: radiometric and calorimetric approaches

This paper presents a new technique for measuring total emissivities at room temperature involving a multifrequency sine wave thermal modulation. The infrared output signal as well as the sample’s front side temperature are measured. Experimental data and a one dimensional model are compared, yielding identified values of diffusivity a, Biot number Bi and E, the latter being defined as the ratio of the sample to reference emissivity. Using Bi, emissivity can be also reached, so emissivity of a thermally thick sample can be reached through two different approaches. Results have been obtained for a 5mm thick sample of PVC, and it is shown that they are well concordant with integrated directional measurements.