Study On Strain Sensing Network Of Distributed FBG

In this dissertation, strain-sensing network of distributed FBG is designed systemically and researched by experiment. Based on analysis of domestic and foreign study actualities on FBG, development trend and several main problems of FBG sensor in application are summarized. And in the need of practical strain-sensing system of distributed FBG network, we research the following five aspects such as design for FBG sensor, signal demodulation of FBG strain-sensing network, multiplexing and addressing, light source design and temperature compensation.In the first place, start with theoretic model of distributed FBG strain-sensing network, sensing principle of fiber Bragg grating is analyzed and sensing model created. On the basis of analyzing advantages and disadvantages of several familiar multiplexing and demodulation techniques, a mixture multiplexing method that combines optical frequency domain reflectometry(OFDR) and wavelength division multiplexing(WDM) is proposed to address FBG sensing array. At the same time, tunable narrow-band light source, which is composed of wide-band light source and tunable optical filter, is adopted to demodulate multiplex signals. The proposed system scheme is testified to be feasible by analyzing theoretically and researching experimentally.In the next place, the constituent modules of distributed FBG strain-sensing network are analyzed on principle and designed. Especially, the performance parameters of the FBG sensor are designed concretely. Due to temperature performance of FBG, a reference FBG is adopted to compensate temperature and the compensation principle is expounded. Moreover, this scheme not only realizes temperature compensation but also reduces repeatability error of FFPTF and errors from power fluctuation of light source, noise of PD and noise of electro-circuit.In the end, temperature and strain performance of FBG is tested and strain-sensing demodulation experiment based on tunable light source is made. And simulation is made to demonstrate the process of addressing FBG array. In addition, various factors that influence on system measurement accuracy and their solutions are expatiated.