Study And Application Of Encoding Fiber Bragg Gratings Sensor Network

Sensors being widely used in the world are always the research hotspot. Fiber Bragg Grating sensors can work in the area of strong electromagnetic field, high temperature, corruptive and explosive bad conditions, therefore have more applications than other sensors. It take digital measurement technology, has the characteristics of high precision, high stability, immune to environmental disturbance of all sorts of factors. However, Fiber Bragg Grating sensing technology in the present has the disadvantage of too small system capability of sensors, this limits its applications in great and complicated engineering. In the same time, that the quantity of sensors in this system is too small makes the cost per sensor too high. It impairs its contest ability in markets. If we can increase the capability of this system, the cost of a single sensor would decrease, so more areas will benefit from its use.This paper study a new kind of encoding Fiber Bragg Grating sensing system, it introduces a new dimensions encoding fiber grating sensing multiplex method, as is to fabricate two or more FBGs with different peak wavelength in the same location of the fiber, called encoding FBG. The Bragg wavelengths of the FBGs are used to encode the temperature , stress , pressure of the environment. As the environment parameters change, the codes which are the Bragg wavelengths of the FBGs accordingly change in the same time and in the same location, so as to increase the system capability, realize the measurement of temperature stress and pressure for special engineering (such as oil tank, power station, tunnel) in a way of distributing measurement.Encoding Fiber Bragg Grating with a few more cost can provide several times of information as single Fiber Bragg Grating. It not only can realize multiple parameter measurement, but also introduce encoding technology into sensing areas, combining the sensing technology and the encoding technology together. Although Fiber Bragg Grating sensing technology has high precision, high stability of long term, the cost of the demodulation equipment is very high. It limits its application. The fabrication of Encoding Fiber Bragg Grating and the implementation in the Encoding Fiber Bragg Grating sensing system makes it not only keep its advantage but also increase the capability of single system, so as to get a strong basement for market application.This paper come down to material , optics , mechanic and electrics, the contributions of this paper are:1. Analyze the existing multiple-sense technology based on FBG and compare the system capability of each technology, such as capacity, cross-talking and so on.2. Design encoding FBG sense network, including producing and preparing FBG sense array, studying wavelength demodulation system which is fit for different physical measurement, compiling decoding program and reconstructing measured physical phenomenon by multi-sensor information fusion technology.3. Use metalized encapsulation technology to prepare FBG sensor, whose sensing character is better than traditional technology testified by experiment.4. Develop double-edged wavelength demodulation system, which is fit for high-speeded shifting measure and prove the system capability in theory and experiment.