Highly-Sensitive Lock-in Thermography of Local Heat Sources Using 2-Dimensional Spatial Deconvolution

A lock-in thermography system is introduced, which allows temperature modulations in the 10 μKrange to be detected. Under certain conditions (homogeneous infrared emissivity and thermal properties, good signal-to-noise ratio), the spatial resolution of lock-in thermographic investigations of local heat sources in electronic devices can be improved by spatial deconvolution. An iteratively working "vectorial" deconvolution procedure is presented, which takes into account the wave nature of the oscillating temperature field. Both heat sources lying at the surface and sources buried at a certain depth can be evaluated. The possibilities of this procedure are demonstrated by simulations and by the deconvolution of experimental lock-in thermograms.