Distributed Temperature Sensing Using Phase-Sensitive Optical Time Domain Reflectometry

Abstract: This thesis explores and evaluates the temperature measuring capabilities of a phase-sensitive optical time-domain reflectometer (φ-OTDR), which exploits Rayleigh backscattering in normal single mode optical fibers. The device is constructed and its setup explained, and a protocol for making temperature measurements with it is developed. Performance tests are made and the device is shown to achieve fully distributed temperature measurements on fibers hundreds of meters in length with a spatial resolution of 1 m and a temperature resolution of 0.1 K. In addition, the capabilities of the device to measure normal strain in the measurement fiber are tested using the same approach, albeit with less success. The device is capable of very precise measurements, making it very sensitive to the environmental conditions around the measuring fiber but also susceptible to disturbances. Some discussion is had on how to avoid or deal with these disturbances. Furthermore, the technique is shown to be able to run in conjunction with other φ-OTDR measurement techniques from the same device simultaneously.