Development of temperature-compensated fiber optic strain sensors based on fiber Bragg gratings

The development of temperature compensated fiber optic strain sensors based on fiber Bragg gratings is reported. The various sensors manufactured and tested include a stainless steel capillary tube-encased Bragg grating, a partially-bonded Bragg grating, and a fully embedded Bragg grating. Strain and temperature resolution is accomplished by measuring the characteristic Bragg wavelength shift of each Bragg grating sensor relative to its initial wavelength. Another measurement technique used involves calculating the differential strain measurement between two dissimilar resistive strain gauges to determine strain and temperature. Testing is done using both a self-made convection and industrial oven to regulate the temperature, as well as applying strain to the specimen via bending or tension. The performance of the sensors in tracking the strain and temperature in variable strain and variable temperature environments is reported and evaluated. The development of an in-lab convection oven and a stress machine specifically designed for this thesis is also described. Suggestions are made for improvements to the sensors in addition to further developmental research and possible practical temperature compensated fiber optic strain sensor applications.