Two-dimensional Surface Temperature Field Using Thermographic Phosphor Thermometry

Thermographic Phosphor Thermometry (TPT) is a non-contact luminescence-based method for mapping surface temperatures with high spatial and temporal resolution. Ceramic phosphors doped with rare-earth/transition-metal ions emit temperature-dependent light. We apply magnesium fluorogermanate (MFG) with hydroxypropyl cellulose (HPC) binder (mass ratio 1:3) as a coating on aluminum plate, then vacuum-dry and cure at 150 °C. Calibration setup uses a 385 nm UV-LED and a high-speed camera with a narrow band-pass filter; the LED is pulsed via a function generator to measure phosphorescence lifetime. Lifetime calibration begins at room temperature and spans to 350 °C to construct a lifetime-temperature correlation. We will systematically vary excitation and detection angles to quantify angular sensitivity. We show lifetime, and thus inferred temperature, to be angle-insensitive, offering a practical advantage over IR thermography and intensity-ratio methods for accurate measurements on complex, curved aerospace surfaces.