Research Of Double Matched Fiber Optical Grating Demodulation System

Fiber Bragg Grating (FBG) sensor is a kind of new kind of fiber sensor. The made-up new kind of fiber sensor is base on the FBG's center wavelength sensitivity characteristic to temperature and stress. Except of having the function of traditional electrical sensor the FBG sensor has the virtue of against electromagnetic interference, great measure range, wide dynamic range and good stability. FBG sensor can be used domain is extensive. In fiber sense technology and system of major project establishment health and security monitor domain. The fiber sensor can be used in the security monitor of the bridge, dam and other large-scale construct health and the measure of earthquake proofing construction. The survey of libration and stress not only need sensor has better sensitivity and good frequency spectrum reaction, and the survey need demodulation system has better precision to gain exact value of be measured non electrical quantity. So the demodulation of FBG sensor is virtual important for FBG sensor's application.In this paper first of all the fiber grating's development trend, classification and applied current situation is summarized. Follow of that, the paper introduces fiber grating's sense principle and mostly optics performance. And introducing fiber grating's strain sense model, temperature sense model, strain and temperature cross sense model. Then analyzing the presently existent various demodulation methods' principle and relative merits educe a kind of high cost performance double matched fiber optical grating demodulation system. The demodulation method is based on the traditional matching method and it adopts the mode of two matching FBGs parallel connection. Comparing with ordinary matching the double matched fiber optical grating demodulation method has a certain extant improvement. In the paper the double matched fiber optical grating demodulation system is designed which is adopts SCM as the core of signal manage system and use stepping motor to tune matching grating to achieve the demodulation of temperature and stress which is sense by sensor. In demodulation system scheme out relevant software program, including of data gather, data optimize manage, display program and step motor driver program. The program makes sense signal can be automatically demodulated. Utilizing the designed fiber optical grating demodulation system, accomplish FBG's strain characteristic experiment, matching grating's step motor tune experiment and FBG's sense signal demodulation experiment. Through the analysis and processing results of these experiments, validate feasibility of fiber grating matching demodulation method. At last, base on analyzing the error and precision of the data bring forward the farther resolve.