Non-intrusive temperature measurements using three-color laser-induced fluorescence

This paper presents a new temperature measurement technique in a liquid, based on laser-induced fluorescence of rhodamine B. The fluorescence intensity is detected on three spectral bands, where the ratios between the emission of each band determine the temperature while correcting for the effects of fluorescent re-absorption. In addition, the influence of parameters such as probe volume size, dye concentration, and Beer's absorption is removed. The principles of the technique are described in this paper, and the technique is demonstrated on a heated liquid jet studied under a constant and a spatially variable dye concentration.