Excitation of thermographic phosphors using a blue light emitting diode: Spectral characteristics and instrumentation applications

A blue light emitting diode (LED) has been used as the excitation source in a series of sensor-related characterization studies carried out on thermographic phosphors. The motivation for the described effort is the potential utility of LEDs for fluorescence based thermometry applications. The phosphors that were evaluated included La2O2S:Tb, Gd2O2S:Tb, Y2O2S:Pr, and various other rare-earth activated ceramics. Periodic and pulsed excitation of the phosphors was demonstrated, with LED gate-on times of 10-12 mus at operating levels of approximate to25 V. The spectral response of the phosphors under these conditions is described, and the implications of such devices for the design of electro-optic instrumentation systems (including remote thermometry applications) are discussed. A beneficial finding of this work is that a good match between the LED emission spectrum and the phosphor excitation spectrum is not required in order to produce useful, detectable fluorescence. (C) 2002 American Institute of Physics.