Optical Fiber Vibration Sensors Based On Interference Principles

With the rapid improvement of China's overall strength,various industries have become more and more stringent requirements for safety.As one of the important indicators of safety detection,vibration measurement not only plays a vital role in the daily safety assessment of rail transit ? engineering construction and health and medical treatment which are closely related to us,but also in the monitoring of natural disasters such as earthquake and tsunami.The application of vibration sensor reduces the probability of dangerous accidents and protects the safety of people's life and property.However,the vibration detection environment is increasingly complicated,the traditional electric vibration sensor has been unable to meet the demand.Considering the fiber sensor has the advantages of corrosion resistance,anti-electromagnetic interference,large dynamic range,simple installation,small size and so on.Fiber optic vibration sensor has become a research hotspot in the field of security technology in recent years.In this paper,several optical fiber vibration sensors are designed and built based on the interference principle of laser in optical fiber,and the Sagnac interference-type optical fiber vibration sensor is applied and studied.The sensing head of the sensor involved in the experiment adopts optical fiber ring with a radius of 7mm.The sensing head is simple to prepare and corrosion resistant,and the overall volume of the sensor is relatively small,easy to carry.For the processing of vibration signal,this paper adopts the Fast Fourier Transform(FFT)method,which can accurately determine the frequency of vibration signal through the frequency domain map after transformation,and reduce the impact of noise in the environment on the data processing results by adding filtering program.It is found that the Sagnac interferometric vibration sensor has the best vibration response test,and its performance is significantly better than that of the single fiber vibration sensor and the Mach-Zenhder interferometric vibration fiber sensor.The frequency response of this type of sensor is accurate.At the same frequency,the amplitude of FFT transform has a very good linear relationship with the amplitude of vibration signal.Based on the excellent vibration response performance of Sagnac interference vibration sensor,the application test of noise and heart rate signal is carried out,and the test results are satisfactory.