Accurate measurement of local surface temperature with thermal imagers

Two dimensional thermal imagers are becoming widely applied to monitoring heat dissipation in designing and fabricating electronic devices. However, the true local surface temperature is usually not obtained without rigorous calibration, due to difficulties such as unknown emissivity, poor imaging quality of the optics, and background radiation. In this presentation, a method to overcome these issues are presented, which makes use of the emissivity distribution pattern detected by the thermal imager by superimposing a modulated background radiation. In particular, in this article, the size-of-source effect caused by the poor imaging quality of the imager is shown to be overcome by the proposed method.