High speed heterodyne infrared thermography applied to thermal diffusivity identification

Abstract

We have combined InfraRed thermography and thermal wave techniques to perform microscale, ul- trafast (microsecond) temperature field measurements. The method is based on an IR camera coupled to a microscope and synchronized to the heat source by means of phase locked function genera- tors. The principle is based on electronic stroboscopic sampling where the low IR camera acquisition frequency facq (25 Hz) undersamples a high frequency thermal wave. This technique permits the mea- surement of the emissive thermal response at a (microsecond) short time scale (microsecond) with the full frame mode of the IR camera with a spatial thermal resolution of 7 μm. Then it becomes possible to study 3D transient heat transfer in heterogeneous and high thermal conductive thin layers. Thus it is possible for the first time in our knowledge to achieve temperature field measurements in hetero- geneous media within a wide range of time domains. The IR camera is now a suitable instrument for multiscale thermal analysis.