Conventional temperature sensors, such as thermocouples or resistance thermometers, are widely used to monitor and control a huge range of processes from manufacturing aircraft engine turbine blades to sterilising food products.
However, they don’t measure the temperature directly, instead they typically possess some property, such as voltage or resistance, which varies with temperature and can be measured. These thermocouples or resistance thermometers therefore need calibrating regularly, so that users can have confidence in the measurements. This can be costly and time-consuming.
For some industrial applications, especially where the temperature measurement is linked directly to user safety, such as in aviation, or where there is also gamma radiation present, any improvement in confidence that can be made is crucial to support innovation.
To overcome the need for calibration, the thermometer must measure temperature directly.
This has not been done before, at least, not for practical in-contact measurements without large rooms of highly expensive electronic equipment!
The thermometer must not be sensitive to any degradation of the component materials and, ideally, be able to be used in environments with high temperatures, contamination, vibration and ionising radiation.
Eliminating the need to keep checking the performance of the thermometer would improve production efficiency, as periodic removal and replacement would not be needed, saving both time and money.