The Fiber Sensing System With Data Acquisition And Data Processing Based On Virtual Instrument Technology

The fiber Bragg grating (FBG) based on fiber photosensitive characteristic is one of the fiber passive components with potential prospects and broad application in the field of fiber sensing, fiber communication and so on. The virtual instrument is the data acquisition system organized based on computer according to instrument requirement, which is characterized by its excellent integration, high performance, good expansibility and so on. A fiber sensing system with data acquisition and data processing based on virtual instrument technology is proposed in this paper. The system is composed of a tunable laser as the source, the FBGs as the modulation units, and the virtual instrument equipments as the data acquisition units. The reflection spectrum of the FBG is acquired using this system. The sensitivities of temperature and strain are calibrated by calorstat and cantilever beam separately. The data acquired in multi gratings sensing experiments are processed and analyzed by central-wavelength algorithm, weighed wavelength algorithm and linear fitting algorithm separately.The major achievements in this thesis are:1. The filter characteristic of the uniform period FBG is deduced based on mode coupling theory. The theoretical model of strain sensing and temperature sensing using FBG is established based on grating equation, and a demodulation method for simultaneous measurement of strain and temperature is testified.2. The principle and method of data acquisition using virtual instrument technology is illustrated. The noise voltage and the synchronous waveform cycle are tested using the data acquisition equipment of NI corporation. The real time control of the tunable laser is realized with GPIB bus.3. A FBG sensing and demodulation system is established based on tunable laser technology, which acquires the reflection spectrum of the FBG. The sensitivities of temperature and strain are calibrated by calorstat and cantilever beam separately. And the method of establishing a FBG sensing and demodulation system based on tunable optical filter technology is proposed.4. The experimental data for multi gratings sensing system are processed and analyzed by central-wavelength algorithm, weighed wavelength algorithm and linear...