APPLICATION OF A TWO-COLOR LASER INDUCED FLUORESCENCE (LIF) TECHNIQUE FOR TEMPERATURE MAPPING

摘要

Two-color laser induced fluorescence (LIF) technique has been developed and examined to use for full-field temperature mapping of a micro-scale field-of-view in water. The technique uses two fluorescence dyes with different emission characteristics - one is the temperature sensitive dye (Rhodamine-B) and the other is the temperature insensitive dye (Rhodamine-110). The ratio of the two fluorescence emission intensities, therefore, provides a formidable correlation with temperature that does not depend on the laser illumination intensity variation and is free from the possible bias occurring from background noise. In considering the technique for applications to micro-scale field-of-view, the first question that may be asked will be if the technique ensures acceptable accuracy in temperature readings with sufficiently small spatial resolution. In order to explore answers to this question, an extensive calibration for the intensity ratio versus temperature has been performed using a constant-temperature bath and the calibration results have been statistically analyzed to estimate measurement uncertainties. The developed technique measures thermally stratified fields with known temperature distributions that are established inside 10-mm and 1-mm path cuvettes to ensure measurement accuracy and spatial resolution for potential microscale applications.