Study Of Distributed Fiber Bragg Grating Sensor System

Fiber Bragg grating has been used widely in the field of Optic-fiber sense because it has the advantage of good wavelength selectivity and it's reflected wavelength can changed with temperature and strain around it. Different spots of same optic-fiber can be tested, because different fiber Bragg gratings reflect different wavelength. This paper introduces a new way to demodulate the sense signal of fiber Bragg grating, which utilizes the effect of anti-piezoelectricity to change the length of optic-fiber's Fabry-Perot cavity, and then establish the relation between reflecting wavelength of fiber Bragg grating and driving voltage of piezoelectricity crystal. This paper analyses the sensing principle of fiber Bragg grating in theory. According to the fiber Bragg grating's speciality of easy to multiplex, designed the distributive sense system of fiber Bragg grating. The whole system is composed by optic-circuit and electro-circuit. Designed all the specific parameter of optic circuit, and deduced the relation between the shape distortion of piezoelectricity crystal and strain of grating's measured spot. The design of electro circuit includes drive circuit of LED, photo-electricity transforms and the single-chip computer measured data processing system including piezoelectricity crystal's drive voltage sampling, holding and transforming to visible measuring data. In the process of system's design, used orCAD/Pspice9 to emulate the hardware of circuit, besides, used the WAVE emulate system to emulate the software. Designed the scheme of experiment and operated the whole distributed fiber Bragg grating system by using optic-circuit and basic electric circuit. After the compare between experimental results and the measuring results of BGD-L05A fiber grating demodulator obtained the precision of the system. The result of experiment indicates that the design was reasonable and receivable. And the system has the virtues such as high sensitivity, good stability and strong ability of anti-jamming. As a result, it can realize the high precise, self-motion, synchronizing and dynamic measurement. In the end, this paper points out the improvable segment of the system and presents the method and proposes to solve the existing problem.