The Research Of Fiber Grating Sensing Technology

Fiber grating has the characteristics of small dimension, light in weight, approval of integration, resisting of electromagnetic interference, being capable of realizing wavelength encoding, and so on. Fiber grating is of great applicative prospect in sensing fields. There is a real application in fields such as petrol-chemical, power industry, medical science and energy, etc in recent years. The key point in fiber grating sensors lies in precise measurement of minute shift of Bragg reflecting wavelength, which is demodulating the coded signals of wavelength. Though it is can be achieved by Optical Spectrum Analyzer with high resolution, Optical Spectrum Analyzer can not be applied into practical situation because of its huge-size and high-cost. In order to exploit a wavelength demodulation instrument with high precision, good stability and low cost, there are a lot of jobs to be done, which is the key to make fiber grating sensing technique utilized and industrialized.In this complicated research dealing with optics, mechanic and electrics, combine the data collecting card, a research of the application of stress sensing with fiber grating is shown in this paper.The main contents are as followed: Firstly, the recent developments in the technologies of sensing fiber grating are reviewed. Introduce the principle characteristic of fiber grating and the sensing principle. Summarize the typical demodulation methods, and analyzing comparing their advantages and disadvantages. Then a new demodulation in fiber grating based on matching has been given in practice. Design and analyze the hardware and software of the demodulation system. A tunable filter with cantilever beam is given and experimented. This designed demodulation system is used in stress measurement and experimented in sensing and demodulation. And the experiment result is analyzed and treated. The feasibility of fiber grating demodulation system is given by the result.The demodulation system based on matching filter method shows some potentials of the practical application. The phonic route gives more facilities for the practical application, and the cost is cheaper. The method and results described in this thesis are conducive to the advancement and applications of fiber grating sensors and technique of tunable filtering with cantilever beam.