Theoretical And Experimential Research On Michelson All-fiber Acceleration Seismic Geophone

Seismic exploration method is an extraordinary important portion of the seismic exploration, while seismic geophone is the first link in the normal working of seismic exploration instrument, the indispensable equipment. The good or bad of the seismic geophone's performance influences the whole seismic exploration technology.The project"Michelson All-Fiber Acceleration Seismic Geophone"is supported by not only Natural Science Foundation of Tianjin, but also BGP CNPC. This geophone could be sorted into a kind of phase modulation optical fiber sensor, which bears some unique advantages such as high sensitivity, anti-electromagnetic, low distortion, wide bandwidth, high degree of accuracy and environmental ruggedness.This paper analyzed and investigated in depth the principle of Michelson All-Fiber Acceleration Seismic Geophone System and the signal processing system based on alternate current phase tracking homodyne compensation technique. The design and debugging and the research on practical application of the computer analysis program for the Geophone output signals were accomplished with the FFT spectrum analysis technology, the ratio spectrum correction and the random search algorithm. Not only the analysis of the multi-frequency signals of the Geophone system and the calculation of the acceleration were finished, but also the information of the included subharmonic such as frequency, amplitude, phase and corresponding acceleration were obtained using this program. An integrate detection system which is capable of comprehensively analyzing the measuring signals consisted of the developed Geophone and the computer analysis program. This system was able to carry out the precision measurement and analysis of the measuring acceleration signals.The test and experiment of the Geophone sample has been carried out, the results indicated that the output signals of the sample in the range of the designed frequency (0～1000Hz) were able to follow the outside quaky signals reliably. The calculation results of analysis program indicated that the calculated values were close to the calibrated values of a standard sensor. The theory and technical fundaments was established for the applicability of this kind of Geophone.