Calibration of Distributed Temperature Sensors Using Commercially Available SMF-28 Optical Fiber From 22 °C to 1000 °C

Optical frequency domain reflectometry (OFDR) is a family of optical techniques which can be used to produce distributed temperature measurements from the spectral shift of an interference pattern based on the Rayleigh backscatter signature of an optical fiber. Adaptive signal processing techniques have recently been used with OFDR to record meaningful spectral shift data from commercially available SMF-28 optical fibers heated beyond 950 degrees C. However, a correlation between the measured spectral shift and temperature has not yet been developed at these high temperatures. To extend the measurable temperature range of OFDR in SMF-28, this work describes the development of such a correlation from room temperature (22 degrees C) to 1000 degrees C. The relationship between spectral shift and temperature change over this range was found to be best characterized by the fourth-order polynomial Delta T = (- 4.241 * 10(-11))S-4 +(- 2.017 * 10(-7))S-3 +(- 3.677 * 10(-4))S-2 + (- 0.8057)S, where Delta T represents the temperature difference compared to the reference temperature, and S represents the spectral shift measured by the fibers. The calibration developed in this work assumes that the fiber has been fully annealed by heating the fiber to 1000 degrees C for a few hours. This paper is the first to demonstrate the calibration and use of SMF-28 distributed optical fiber sensors up to 1000 degrees C, enabled using adaptiveOFDR-based signal processing.

Automated summary

This paper introduces a method for temperature measurement of optical fibers using optical frequency domain reflectometry (OFDR) and develops a correlation between spectral shift and temperature in the range from room temperature to 1000 degrees C. The relationship between spectral shift and temperature is characterized by a fourth-order polynomial, which is validated using SMF-28 optical fibers.