Instantaneous temperature field measurement on a hot surface cooled by impinging jet using thermographic phosphor technique

Thermographic phosphor thermometry was used to measure the instantaneous temperature field of a hot plate cooled by an oblique impinging air jet. For phosphor thermometry, the manganese-activated magnesium fluorogermanate (Mg₄FGeO₆:Mn) was used as a thermographic phosphor, and a pulsed UV-LED with a 385 nm wavelength was used for the light source. A CMOS high speed camera acquired the phosphorescence images with a 655 nm band-pass filter. A simple and fast calibration method for phosphor thermometry using decay constant was suggested and the results were compared to the conventional lifetime based method. In-situ pixel by pixel calibration procedure was adopted to avoid non-uniform illumination problem. The instantaneous two-dimensional imaging of temperature field on the hot plate was visualized in the transient process after starting the impinging air jet cooling.