Accuracy and Survivability of Distributed Fiber Optic Temperature Sensors
Describes tests and results associated with temperature coefficients of fiber sensors.
Obtaining a high accuracy, high spatial resolution temperature profile of critical test artifacts and test components has long been the holy grail of temperature sensing. Optical Frequency-Domain Reflectometry (OFDR) facilitates the use of unaltered optical fiber as high resolution distributed temperature sensors. Coating selection is a major parameter to consider in determining the best sensor choice based on the operating environment, especially the temperature range. We assess the performance of several fiber sensor coatings for the purpose of converging to the best sensor option for the -40°C to 200°C range. Stripped and carbon coated fiber maintain uniformity through the temperature cycles, resulting in accuracies of +/-0.5°C. A packaged fiber sensor was also held at 551°C for 3000 hrs to measure its performance over time. The survivability and accuracy of fiber sensors at high temperatures provide clear advantages compared to single point thermocouples in terms of displaying localized temperature variations.