Compact sapphire fiber sensor of transient temperature and relevant calibration technique

A compact sapphire transient temperature fiber sensor, suitable for harsh environments and relevant calibration techniques are introduced. The sapphire fiber sensor, with specific high temperature ceramic film deposited on its tip, serves as the temperature sensing blackbody radiator. The static calibration of the system is carried out in the thermostatic region, which is close to the molten pit of an ingot heated by an oxyacetylene flame to a temperature slightly lower than the melting point of the material. To measure the dynamic response time, an exciting source of a step-up CO₂ laser beam is used. The experimental results show that the newly developed sapphire fiber sensor, with a response time in the order of 10^-2 s, can be used to measure transient temperature from 800°C to 1900°C under a harsh environment and a 1% uncertainty of calibration can be achieved.