Characterization of the Ce,Pr:LuAG phosphor for Co-doped aerosol phosphor thermometry

Abstract

The Ce,Pr:LuAG phosphor is investigated for use in co-doped aerosol phosphor thermometry (APT). The phosphor was characterized by measuring the emission intensity for each ion as a function of excitation laser fluence and temperature. A simplified three-level model was used to interpret and fit the data. The phosphor was then used for co-doped APT temperature-imaging experiments performed in a heated air jet up to a maximum temperature of 694 K. The three-level model fit was used to analyze sources of bias in the imaging measurements. Both ions’ emission intensities show a nonlinear dependence on excitation fluence that can potentially be explained by temperature-dependent ground- and excited-state absorption processes included in the three-level model. Single-shot temperature precision from the temperature-imaging experiments was measured to be 22, 23, and 32 K for mean temperatures of 497, 603, and 694 K, respectively, at a spatial resolution of ~1.12 lp/mm and average fluence of 33 mJ/cm2. The results extend the measurement range for co-doped APT to at least 700 K. The findings also provide a simple model for phosphor signal non-linearity with excitation fluence for low activator ion concentrations, and provide a method for estimating temperature bias from several sources including laser fluence.