Optical differential temperature measurement with beat frequency phase fluorometry

摘要

We present, to the best of our knowledge, a new method for differential temperature measurement based on thermal sensitivity of the fluorescence lifetime of thermographic phosphors. Pairs of thermographic phosphors are excited with intensity-modulated light at frequencies omega and omega + Delta omega The phase shift Delta theta of the summary fluorescence intensity beat signal envelope is measured. A prototype of a fluorometric differential temperature sensor is developed, and feasibility of the method is experimentally demonstrated with a Sm2+:SrFCl crystal and the D-5(1) - F-7(0) transition for high thermal sensitivity. The observed linear dependence between envelope phase shift Delta theta and temperature difference Delta T agrees with the theoretical prediction. Sensitivity of S = -0.97 degrees/degrees C was achieved. This method could also be applied to differential measurements of any parameter affecting fluorescence lifetime. (C) 2018 Optical Society of America