Accurate surface temperature measurements present vast difficulties in numerous technical applications, especially when imaging fast temperature changes. One example is spray-induced surface cooling, where temperature variations occur on the sub-millisecond timescale. Phosphor thermometry relies on changes in the photoluminescence properties (typically the lifetime or the emission spectrum) of phosphor materials for temperature determination. For temperature imaging in situations where short measurement durations are critical such as on fast moving objects or short and intense heat transfer events, the spectral method is preferred. However, in many situations, fluorescence signals over a broad spectral range originate from fuel, flame radicals, optical windows or even the chemical binder used to coat the phosphor material and may interfere with the measurements.