APPLIED OPTICS

Long-Distance Thermometry

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Science  03 Oct 2003:
Vol. 302, Issue 5642, pp. 19
DOI: 10.1126/science.302.5642.19b

From environmental issues, such as groundwater monitoring, to safety issues, such as fire detection in buildings, the one parameter that is most often measured is the temperature. Although individual temperature sensors can be installed throughout a system, for some applications this might prove prohibitively expensive or may just be unsuitable. What about a temperature sensor that could be unwound from a spindle and cover distances up to 50 km? Cho et al. show that optical fibers can be used for such applications. By detecting and analyzing the backscattered light arising from the interaction between pump and probe pulses launched into the fiber, they could measure temperature differences along the 50-km fiber, with 1°C sensitivity at the front end of the fiber to 13°C at the back end and with a spatial resolution of 15 m. For applications requiring fast continuous monitoring over long periods of time and long distances, such a distributed temperature sensor should be particularly useful. — ISO

Opt. Lett. 28, 1651 (2003).

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