Design of a Multi-Node Cascading Optical Fiber Sensing System Based on LabVIEW

A remote multi-node optical fiber sensor system is designed to detect a long-range object.The whole structure is a connection in series from a local control node to all the remote sensing nodes with bi-directional fiber links.At the local control node,the optoelectronic devices are shared including the light source,photodetectors and so on,and the data processing circuit is realized with virtual instrument.So there is only optical path made up by the sensitive element and passive optical devices at each remote sensing node.Besides,as a result,time division multiplexing can be carried out directly.A threenode system for methane gas detection is constructed as an example of experiment and calculation.The result shows that the system can work efficiently,and the relative error of the first sensing node can be reduced to below 0.2%by cycle detection.