Limitations of ICCD detectors and optimized 2D phosphor thermometry

Abstract

This paper presents investigations on the limitations of intensified CCD (ICCD) cameras when performing quantitative 2D temperature measurements using thermographic phosphors. The temperature is evaluated using a two-color ratio technique, which demands high signal linearity of the detector. However, this work shows that the ICCD cameras used suffer from nonlinearity at levels of irradiance that do not necessarily produce particularly high count levels, i.e. well below the saturation limit of the A/D converter. For the phosphor thermometry, this results in false absolute temperature readings and decreased measurement precision. The results show that there is a useful workspace in the irradiance/camera gain combination where the detector should preferably be used. A response function for the ICCD camera used is constructed. Furthermore, in order to perform quantitative measurements, there is an upper limit of counts that should not be exceeded. This limit must be investigated for each experimental configuration since it depends on the characteristics of the specific light source and also varies between different cameras.