Development of Sapphire Optical Temperature Sensing System Used in Harsh Environment Sensing

A sapphire optical fiber blackbody radiation sensor based on the high-temperature multilayer structure of wolfram and aluminum oxide has been developed. Through the analysis of Planck's law, the linear relationship between the temperature and the square root of the voltage is theoretically deduced. Radio frequency magnetron sputtering method is used to sputter and deposit high-temperature wolfram metal film and aluminum oxide film on sapphire fiber. In order to meet the needs of real-time temperature measurement, an online acquisition system of optical signals is designed to complete the demodulation and storage of signals. The high-temperature experiment results show that the temperature response sensitivity is 0.00113 V1/2/°C between 300 °C and 1750 °C, and it can work stably for more than 10 h. The sensor is calibrated in the metrology institute, where a maximum quoted error of 0.84% within a range between 900 °C and 1600 °C is proven. Compared with the traditional high-temperature measurement method, the sensor has the advantages of compact structure, antielectromagnetic interference, large measuring range, and good linearity, which can be widely used in the sensing and measurement of extreme high-temperature environments, such as aeroengine tail injection temperature monitoring and combustion chamber temperature monitoring of aeroengine simulation test benches.