Simultaneous Temperature And Strain Measurement Based On Fiber Loop Mirror And FBG

In the field of optical fiber sensors, fiber loop mirror (FLM) and fiber Bragg grating (FBG) are both considered as sensing elements which can be used for strain sensors. However, one of the severe problems is that both of them are easily influenced by temperature, causing the cross-sensitivity between the strain and temperature during the measurement. Therefore, the strain can only be measured accurately by FLM or FBG if the cross-sensitivity is overcome ahead of time.In order to solve the above problem, FLM and FBG are combined to realize the simultaneous measurement of temperature and strain in this thesis.Not only are multi-parameter discriminated simultaneously, but also cross-sensitivity is eliminated. The proposed scheme is very useful in the field of intelligent building monitoring and ocean exploitation. The four main contents of this article are as follows:Firstly, simultaneous measurement methods of temperature and strain based on FLM, FBG and the combination of the two are all summarized detailedly. By comparing the merits and demerits of these methods, it provides ideas for the design of the proposed scheme.Secondly, temperature and strain features are discussed. Several novel FBG enhanced-sensitivity programs are proposed after the introduction of the existed enhanced-sensitivity techniques. Besides, Theoretical model of fiber loop mirror (FLM) is established and temperature features are simulated. Based on the above studies, the combination of FLM and FBG is proposed in this paper and the corresponding feasibility is analysed theoretically.Thirdly, according to the above design, experimental platform is set up. Temperature and strain sensitivity coefficients are calibrated within the range provided by the lab. Then the comparison between the theoretical value and experimental value is made.Finally, the connection between the optical spectrum analyzers (OSA) and computer is made through the LabVIEW software in order to realize the real-time display of temperature and strain parameters. As a result, the related temperature and strain values can be shown timely on the board of the software.