Optical fibres are building blocks of modern high-speed telecommunication networks. Researcher have now found how to use them as thermometers

Optical fibre reinvented as temperature sensor

Optical fibres are the basic building blocks of modern high-speed data networks. Spanish researchers have now found how to use them to measure temperatures of mechanical systems.

The novel application of optical fibres in industrial settings could help prevent overheating and subsequent damage of various machines that cannot be monitored using conventional thermometers such as infrared cameras.

“The system is calibrated so that it can start measuring at 300 degrees, and it could go up to 1,000 degrees because the fibre, which is made of silica, can withstand very high temperatures,” said Carmen Vázquez, a tenured professor at the Charles III University of Madrid, Spain, who led the research.

Infrared thermal cameras, usually used in such settings, require a clear view into the tool. Other sensors, such as thermocouples, can’t be used either as they would be quickly destroyed in such an extreme environment.

A fibre-optic pyrometer, on the contrary, is not only exceptionally resilient but also thinner than a human hair, allowing it to fit into the narrowest of spaces.

“The optical fibre is about 62.5 microns [um],” Vázquez said. “To give you an idea, the diameter of a hair from a young person is, on average, about 100 microns.”

The optical fibre determines the temperature of an object by the amount of radiation it emits. As the radiation increases, so does the temperature.

Insight into thermal fluctuations inside costly machinery could help prolong the lifetime of those tools used daily in many industries to perform tasks requiring the highest level of precision.

Apart from indicating immediate problems, detailed temperature data could help optimise the performance of the machines and reduce wear and tear.

“During the mechanised production of parts of components, it is very important to avoid extreme temperatures or changes in phase that are related to worse performance and fatigue,” Vázquez said,

The researchers believe a prototype could soon be introduced in various sectors including aerospace and  biomedical applications.

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