The Research On Fiber-optic Accelerometer Based On Fabry-Perot Interferometer

With the development of science and technology,optical fiber sensor has become a hotspot in the field of sensing.Fiber-optic accelerometers(FOAs),with its advantages of high sensitivity,immunity to electromagnetic interference,wide dynamic range and easy to multiplexing,have achieved great development and were widely used in the fields.Their applications include perimeter intrusion,seismic monitoring,energy security,transportation,marine vessels,aerospace and engineering structural health monitoring,etc.In this paper,we report a novel external cavity FOA based on Fabry-Perot(F-P)interferometer to realize high sensitivity,high-precision and high dynamic range,simultaneously.Using fast full-spectrum white light interferometry(WLI)demodulation scheme,the sensing system can achieve high speed absolute acceleration measurement.The main work is as follows:Firstly,based on the principle of F-P interferometer and mechanical model of acceleration sensor,the sensing mechanism of the fiber-optic F-P accelerometer is analyzed theoretically.The accelerometer with a mesh diaphragm mass-loaded sensing structure is designed to carry out the sensing tests.Then,the results indicate axial sensitivity of 3.86?m/g within the frequency bandwidth of 10–120Hz for the sensor.In experimental tests,the acceleration resolution achieve 8.5?g within a±30g maximum measurement range,and the accelerometer offers the best dynamic range 10~6.Moreover,FOA sensing system precisely recorded all key features and events in acceleration during the ascending process of an elevator.These features include bumps,high-frequency vibration,low-frequency acceleration,speed,and braking distance,which are among the main factors to concern about the comfort and safety of an elevator.The performance of the system evaluated in lab tests and demonstrated in an elevator field test prove very attractive to applications,such as engineering structure health monitoring and transportation security monitoring,etc.In order to manufacture two-axis acceleration sensor,the sensing element of single-axis F-P accelerometer is improved.The theoretical analysis and manufacture process of the two-axis F-P accelerometer are implemented,then performance of the sensing system is evaluated in tests.The results indicate axial sensitivity level of~1?m/g within a 10~5 dynamic range for the sensor,and sensor has also a significant rise in frequency bandwidth.In experimental tests,the cross-sensitivity of the two-axis accelerometer is evaluated to be lower than 5%,which meet the requirement of low crosstalk multidimensional acceleration sensing.By comparison with the commercialized fiber-optic accelerometer Os7100 and Os7510,the proposed F-P accelerometer have performance advantage in the fields,such as sensitivity,resolution,dynamic,etc.Finally,the work is summarized,and the further optimization of the accelerometer is discussed.