Study On Geophone Based On Fiber-optic Interferometer

Research on geological disasters, such as earthquakes, which occur frequently in recent years and cause great damage to people's lives and properties, has become a hot issue and the seismic detection technology has been promoted to a great level, but the geophone, which still adopts the traditional method of mechano-electric conversion and analog signal transmission with disadvantages of poor anti-interference ability,low sensitivity and low dynamic range,etc, is out of breakthrough and limits the development of seismic detection technology.In thesis, an optical fiber sensing system, based on fiber-optic interferometer, is proposed for seismic detection. Firstly, the analysis of geophone structure lays the foundation for seismic detection system design. Secondly, geophone structure, which consists of spring lamination, electromagnetic damper and Fizeau fiber interferometer, is designed. Finally, the system, in which servo loop was introduced to demodulate the signal, succeeds in detecting the artificial earthquake wave.Experiments demonstrate that the stable system, which is insensitive to environmental factor such as temperature changing and electromagnetism disturbing,can detect he artificial earthquake wave effectively with amplitude response to the wavelength level, the output voltage of low-frequency response to milliVolt level and dynamic range from a fraction of a Hz to almost 100 K Hz.