A High Resolution Interferometric Fiber-Optic Temperature Sensor "FOTS"

This paper introduces an application of a single-mode optical fiber as a temperature sensor. The application is based on the Michelson-interferometer principle. A single mode optical fiber of several meters is loosely wound around a foam cylinder. The interferometric principle used in this work gives the advantage of having the output directly as a digital readout after converting it into electrical signal. The detected number of counts (fringes) directly represents the increase or decrease in temperature. The output of the fiber optic sensor is compared to that of a semiconductor temperature sensor gauge. The correlation between the two sensors is presented. Results from the fiber optic sensor introduced within this article show high sensitivity in the range of 52middot10^-4degC, stability and reproducibility. Finally, the obtained sensitivity proved to be very high compared to other techniques used in most published articles of fiber optic temperature sensors. In addition to the high sensitivity the FOTS introduced in this work is versatile and may serve many applications where temperature plays an important role and very small fluctuations have to be registered.