A temperature sensor includes a photon source, a fluorescent element and a photodetector. The fluorescent element includes a temperature-insensitive first fluorophore and a temperature-sensitive second fluorophore. The photodetector includes a first photosensor exhibiting a first spectral responsivity and a second photosensor exhibiting a second spectral responsivity. To measure a temperature of a surface, the fluorescent element may be placed adjacent to the surface and irradiated with a photon beam. First photons emitted from the first fluorophore and second photons emitted from the second fluorophore are collected. The first and second photons may be transmitted as a single dichromatic beam to the photodetector. The photosensors generate two different photodetector output signals, the ratio of which may be correlated to temperature.
Fluorescence Based Thermometry
Lewis, J., Piascik, J., Klem, E., & Cunningham, G. (2015). IPC No. U.S. Fluorescence Based Thermometry. (Patent No. 9022649).