Research On Vibration Measurement Method Based On Optical Fiber F-P Interference

Fiber Fabry-Perot(F-P)interference sensor is a typical structure of optical interference.It has a large dynamic range,high sensitivity,high stability,and anti-electromagnetic interference.It is suitable for extreme environments and can realize long-distance multiplexing.The advantages.Vibration measurement is an important direction in the application of interference technology.For most single-channel measurement systems,the differential structure can reduce the system’s common mode noise and errors caused by software processing,increase the signalto-noise ratio,and improve measurement accuracy.However,a single-channel system can only achieve vibration measurement of one point.When measuring multi-channel parameters,multiple repeated measurements are required,which results in processing redundancy.In order to reduce the measurement error and provide a new structure for two-way measurement,this paper builds a vibration measurement system based on the optical fiber F-P interference technology.The specific work is as follows:1.In order to reduce the structural redundancy in the dual-channel vibration measurement and the signal spectrum aliasing caused by the single photodetector(PD)acquisition,the advantages of the circulator’s one-way transmission are used to construct an independent measurement dual-channel vibration measurement system.Through simulation analysis,the validity and feasibility of independent measurement of dual-channel vibration signals are confirmed.2.In order to reduce the problem of small information loss caused by the software filtering of the upper computer,the phase difference of π/2 between the two ends of the output arm of the coupler is used to construct a structure based on the differential measurement of vibration to process the interference signal and reduce the signal to be measured.The common mode noise increases the signal-to-noise ratio and reduces the interference of noise to the optical fiber measurement process.3.In order to evaluate the performance of the differential-based F-P vibrometer,a differential vibration measurement system based on the PDV-100 Doppler vibrometer was designed.In the process of measuring PZT at the micrometer level,through the analysis of the displacement-voltage curve fitting the differential vibration measurement,single PD vibration measurement and PDV vibration measurement,the results show that in the laboratory environment,the FP interferometer is within the micrometer measurement range.The vibration measurement accuracy is closer to the PDV vibration measurement result,which can effectively reduce the displacement reconstruction error during single PD measurement.