Intrinsic Fibre Strain Sensor Interrogation Using Broadband Interferometry

Strain measurement is an essential part of quality control and monitoring for many engineering purposes. One of the best types of strain sensors is a fibre optic strain sensor.

Optical fibre sensors have the exclusive upper hand and unique features compared to more traditional sensors, which make them very enticing for various purposes, notably those with demanding conditions where other conventional electrical sensors normally fail. Due to the harsh environment, explosion risks, durability, and massive electromagnetic noises, well-known electrical sensors are impermissible in numerous technical and industrial applications. The fibre optic sensors can endure severe conditions (pressure, high temperature) and offer complete electromagnetic immunity. Thus, fibre optic sensors are a viable alternative for these types of purposes.

This thesis talks about:

•What are the strain and different types of strain sensors?
o Traditional mechanical and electrical strain sensors as well as some backgrounds to what a fibre optic is, and various kinds of fibre optic gauges.
•The advantages and disadvantages of fibre optic gauges.
•Different methods of fibre sensing and their modulation and demodulation techniques.
o Various interferometry sensors and techniques like Michelson, Fabry-Perot, Mach-Zehnder and Sagnac.
•Commercial research about the Fabry-Perot.
o Choosing the Fabry-Perot (Intrinsic Fabry-Perot interferometer)sensor, its advantages over other fibre optic sensors.
•Setting up the testing system and various test steps that were taken, such as building two plastic jigs for the test.
•Data analysis of the system, signal processing (Takeda method), different cropping and filtration of the signal to achieve the slope, and consequently calculate the strain, error%, stability, and various sensor characteristics.
•The conclusion explains the need for the research, how the test was done and what it achieved.