The Research On Technique Of FBG Pressure Sensing Based On C-Shaped Elastic Tube

Optical fibre grating is one of the optical fibre passive devices which have great development in recent years. Because of its unique advantages, it has brilliant prospect in field of fibre communication and sensing.Fibre Bragg grating(FBG) is an optical device of its refraction modulated period, which makes different modules of optical signal coupled in fibre. Its use equals a reflector of high refection. When it is used to a sensor system, it can check strain, temperature, pressure,acceleration, etc. As the key device of the experiment, its character directly influences the result of experiment.The basic theory for FBG has discussed in detail in this article.We introduced the classification of fibre grating,the method for creating fibre grating and its application. We used the model-coupled theory to analyze the spectrum character of FBG , based on which, we analysed the temperature and strain sensing principle of FBG. By temperature sensing experiment, we got a FBG temperature sensitivity coefficient which corresponded to the principle value.In this article, the structure design of a fibre Bragg grating sensor based on the C-shaped elastic tube has been put forward. Based on the FBG strain sensing character and the analysis of surface strain of C-shaped elastic tube, by bending the FBG on a special position of C-shaped elastic tube, we converted the pressure transfered into the C-shaped elastic tube to the central wavelength drift of FBG. By strain sensing experiment, wo got a linear relation expression between the pressure and the central wavelength drift of FBG. Meanwhile, based on temperature sensing experiment and strain sensing experiment, we designed a FBG temperature compensation experiment, by which, the method of reference FBG temperature compensation had been certified.The originality innovation of this article is that we designed a novel experiment system for FBG pressure sensing on C-shaped elastic tube; a novel bending method of FBG had been put forward. By deducing the theoretical data and comparing with the other bending method, pressure sensing sensitivity had been improved remarkablely. FBG temperature compensation experiment certifid the feasibility of the method of reference FBG temperature compensation.