High-temperature remote thermometry using laser-induced fluorescence decay lifetime measurements of Y/sub 2/O/sub 3/:Eu and YAG:Tb thermographic phosphors

An Nd:YAG-laser-based remote sensing system for determining the surface temperature of substrates coated with thermographic phosphors has been developed. The fluorescence decay lifetime versus temperature measurements obtained for Y/sub 2/O/sub 3/:Eu (4.52% Ec) and YAG:Tb (5% Tb) over the temperature range 27 degrees C-1095 degrees C are presented. Both phosphors can be used for continuous temperature measurements over the range of approximately 550 degrees C-1000 degrees C. Stepwise regression analysis is used to calculate empirical relationships expressing temperature as a function of the measured fluorescence lifetimes for both phosphors beyond the onset temperature quenching point. The accuracy of the temperature measurements was estimated to be +or-5%. The intensities of the 611-nm Y/sub 2/O/sub 3/:Eu and the 544-nm YAG:Tb emission lines as a function of temperature are compared.>