Calibration of YAG:Tm at High temperatures and identification of transition dynamics for thermal measurement of surfaces

Thermographic phosphors are often used to measure temperatures in harsh thermal environments because of their non-contact nature, chemical and thermal robustness, and independence on radiative properties [1]. Because spectral emission from the visible region is used to indicate temperature, black-body radiation from high-temperature surfaces can obscure the measurement signal. The 365 nm emission line in thulium-doped YAG could be used in high-temperature measurements because its wavelength is significantly shorter than other emission lines in common high-temperature phosphors. Although the intensity of the emission peak is somewhat lower than the other characteristic lines in YAG:Tm, the lifetime is measurable and shows a strong dependence on temperatures above 900 °C. Gated spectral measurements help identify energy levels responsible for the 365 nm emission.