Communication—Evaluation of Fluorescent Temperature Sensor Materials in Low Temperature Region

A fluorescent temperature sensor using temperature dependence of fluorescent inorganic materials is studied for low temperature measurement. Ruby (chromium ions doped sapphire) is used as a sensor head of the fluorescence thermometer because of long photoluminescence (PL) lifetime and visible emission. In this research, ruby crystal is found to be useful as the sensor head for fluorescence thermometer. In addition, the ruby crystal is potentially useful material for the sensor head crystals to measure low temperature below 0 °C.