Research On Multi-gas Integration Fiber Optic Network Sensor System

The present progress in fiber optics communication technique has greatly acceleratedfiber-optic sensor technique, especially in the application of gas sensor field for monitoringof environmental pollution and explosive gases in various industrial and coal mine.Comparing with the traditional gas detection method, the fiber-optic gas sensor has obviousadvantages that not only can offer high sensitivity and resolution, but also it can realizeremote integration sensing and be inherent safe in hazardous environments. The thesis willintroduce a multi-gas integration fiber-optic network sensor system.This thesis analyzed the principle of gas infrared absorption, and studied the detectablegas variety for fiber-optic sensor system. We introduced the multi-absorption peaksdifferential detection technique for high signal noise ratio(SNR) and set up multi-gasintegration fiber-optic sensor network based on Space Division Multiplex(SDM) techniqueand Wavelength Division Multiplex(WDM) technique.To obtain the comb spectrum, we designed a Fabry-P′erot comb filter. We set up aoptical collimation platform to package the optic sensor unit. As the system is chronically invariety hazardous environments, we designed a practical sensing head with dust-proof,water-proof and breathe freely. We autonomously designed and made a impermeabilityexperimental cell with the characteristic of multi-point and multi-gas synchronous detection.Finally we have done the experiment about one-point and multi-point methane gasdetection and first brought in calibrating light path in order to enhance the stability andsensitivity. We have tested the performance of used active and passive optical device and thewhole system stability. Based on this sensor system, we detected the methane concentrationsin different spots which indicated the system detection precision may come to271ppm andthe different sensor points have the highest consistency and the longest system stability.