Development and application of high-precision fiber optic rotational seismometer
The observation of the rotation of surface motion is of great significance in seismology,geophysics,engineering exploration,and other research fields.Interferometer fiber optic gyroscopes based on the Sagnac effect have attracted extensive attention in the research and development of rotational seismometers due to their advantages of all-solid-state,highly sensitivity and wide frequency response.To enhance the sensitivity of fiber optic rotational seismometers,long fiber loops are commonly employed.However,increasing the length of the optical fiber leads to thermal phase noise and relative intensity noise from the light source within the optical fiber loop,limiting their sensitivity performance.This paper conducts an in-depth analysis on the noises that degrade the sensitivity of fiber optic rotational seismometer.A dual-polarization configuration is proposed using the slow and fast axes of polarization-maintaining fibers,and its optical configuration as well as demodulation algorithm are theoretically analyzed.The results show that the dual-polarization configuration can effectively suppress thermal phase noise and relative intensity noise.On this basis,a three-component dual-polarization fiber optic rotational seismometer DP-Rot3C is developed,and the static and dynamic tests are conducted.The results show that the sensitivity of the seismometer reaches 20 nrad·s-1·√Hz-1,comparable to the French Bluseis-3A.It exhibits a flat response across a frequency range of 0.01～125 Hz and possesses a nonlinearity of less than 6ppm(1 ppm=0.0001％)over a dynamic range of-300 to+300°/s.These results demonstrate that DP-Rot3C has high precision,wide frequency band,large dynamic range and high linearity.DP-Rot3C has been applied in multiple practical scenarios,including artificial active source observation,high-speed-railway seismology observation,natural earthquake observation,and other fields.The above experiments indicate that DP-Rot3C provides a high-precision tool for observing the rotation motion for engineering exploration,seismological research,and other applications.
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维普
