Study On Optical Fiber Stress Distribution Measurement System

To be a safe and economic way, pipe conveying has been paid more and more attention around the world. With the development of the pipe conveying, the technology of leak detection holds the important status in the pipeline safety in production. Because tubing has the character of complex situation, long distance, broad distribution and so on, bring major difficulty to real-time leak detection and locating the leak. For fiber's excellent character of electromagnetic insulation, prevent of flame and explosion, small size and distribution survey, it has a good perspective in application in the monitoring of oil and gas conveying pipe.The paper analyses the monitoring of the oil and gas conveying pipe around the world. After comparing and analysis about a lot of feasible detection method, considering about the manufacture technique, system precision, and the available device home and abroad, optical fiber stress distribution measurement system based on Mach-Zehnder interferometer was chosen. From the sensing theory, the interference factor of two light beams, interference method and some interferometer was analyzed. The relationship of the stress and the phase shift of the Mach-Zehnder interferometer output light were deeply discussed.The system structure of the optical fiber stress distribution measurement system was designed. The operating principle was introduced and the localization equation was induced. After discussion about each part of the sensor, the driven circuit of the laser was designed. The piezoelectric ceramic was applied to modulate the phase of the reference arm of the Mach-Zehnder interferometer, insuring the orthogonality of the light in the detecting arm and the reference arm. Differential amplifier, integrate, and band pass filter was designed. The experiment was finished, the noise signal was analyzed andimproving method was presented.