Research On Fiber Optic Accelerometer System

A fiber optic accelerometer based on Michelson interferometer is described in this paper. The accelerometer has many advantages including simple structure design, high sensitivity and stability, wide bandwidth and resisting electromagnetism interference etc, and it can also be used in many fields, for example: aeronautic and astronautics, inertial navigation, seismic inspection and petroleum exploitation etc, so the research on this fiber optic accelerometer is significant. Firstly, the principle and design of the fiber optic accelerometer based on Michelson interferometer are analyzed deeply in this dissertation. Starting with the transducing mechanism, the relation between the phase change of the optical wave and stress-strain of optic-fiber is derived. Then the relation between stress-strain and acceleration is established, and hence does the relation between acceleration and the phase change. This fiber optic accelerometer is based on Michelson interferometer, and its sensing element is a mass wrapped by single-mode optical fiber. The main working procedure is: the sensing element detects the acceleration signal, and this signal modulates the phase of the wave, then Michelson interferometer turns the phase change into the wave intensity, and put it out to the signal processing system. The signal processing system is the key component for the fiber optic accelerometer system. From the viewpoint of system, the paper analyzes the principle of the signal processing method, and discusses the design consideration of each block of the circuit system. Homodyne demodulation is analyzed deeply, which can detect the phase change and compensate the interference. Finally, to assess its performance, MATLAB is used in the signal processing system and the results show that the output signal is in correspondence with the input signal of the acceleration, which proves the feasibility of the fiber optic accelerometer system. This acceleration sensor detects the signal basically by micro displacement, so if we change the design of the sensing element, we can also measure other physical signals like pressure, angle, flux etc. In a word, this acceleration sensor has very wide application fields.