Distributed Bragg grating sensing: Strain transfer mechanics and experiments.

摘要

The optical fiber sensor is a tool by which a measurement of a thermo-mechanical field inside a mechanical host can be made. It is possible to interrogate the optical fiber sensor with light. The parameters of the in-fiber sensor determine the response of the sensor to lightwave interrogation. Having the sensor response, a reconstruction of the in-fiber structure can be attempted. Successful reconstruction of the in-fiber structure allows an inference of the behaviour of the mechanical substrate. The substrate behaviour is ultimately the information of interest. Extraction of such a measurement may be seen as two sub-problems.; The first problem addresses the ability of the mechanical system to transfer surrounding material information into the optical fiber sensor. It is not the field values inside the optical fiber sensor that are particularly interesting, instead, it is the degree to which the in-fiber field values accurately represent the field values of the surrounding material. It is important to examine the mechanical system's ability to transfer strain from surrounding material to optical fiber sensor. Certainly, if strain information is not transferred into the optical fiber, even an ideal interrogation of the in-fiber sensor cannot report the full strain field of the mechanical host.; The second issue concerns the sensor itself. The reflectivity characteristics of the loaded sensor must first be recovered experimentally, then interpreted in meaningful way. The experimental arrangement to recover the sensor response and interpretation of this data constitute the optical measurement problem.; This thesis examines the two problems.