| Fiber optic sensors based on Fiber Bragg Grating (FBG) technology are found to be a promising technique for measuring parameters like strain, temperature, pressure, vibration, acceleration etc. However, few investigations in displacement measurement using FBG were reported. Most works reported in the literature are related to the displacement measurement in the range of mm.; The purpose of this thesis is to establish a new methodology to characterize material surface by using the Bragg grating fiber technology into micro and sub-micro scales. Three measurands are proposed in the thesis, indentation measurement using one-FBG, indentation measurement using two-FBG and step height measurement. Theories for the new methods are derived and the experiments are implemented. To achieve fine scale measurement, the requirement of large measurement sensitivity is discussed. Monitoring and controlling the force against the substrate is highlighted in the thesis. (Abstract shortened by UMI.)... |
