Based On Fiber Bragg Grating Liquid Level Sensor Technology

The thesis analyzes the sensing properties of the FBG, which makes a great contribution to apply the FBG to sensor, and the thesis also analyzes the mechanical property of the Bourdon tube, which lays the root for making the FBG liquid sensor.According to the theory mentioned above, a up-to-date high sensitive fiber grating liquid level sensor has been researched and developed innovatively by fitting the fiber bragg grating and the Bourdon tube together, in order to measure the liquid level. The key point is that the changes of liquid level is apperceived by the Bourdon tube, which pulls the fiber bragg grating, so that the reflective wavelength of bragg is changed. After making the sensor, the thesis makes theoretical analysis and testing experiment, we can find that the changes of the reflective wavelength and the liquid level are linear in the measuring range. We can also find that the sensitivity of this sensor is quite high. The experimental results show that the sensitivity is 65.771 nm/Mpa on average within the liquid level of 6.5 m.In order to make the demodulating system more practicably, the tunable F-P filter is used in the theoretical analysis and testing experiment, and we can find that, in a move for a periodic sawtooth waves voltage, the changes of the wavelength which drills through the F-P filter controller and the drifting time of the wave shape is linear in the measuring range. And the sensitivity is 25.954 ms/Mpa on average.The research of this fiber bragg grating liquid level sensor is significantly meaningful in the measurement of liquid level which can be used in inflammable environment, for exemple:the oil depot.