高精度光纤旋转地震仪研究及应用  

Research and Application of High-precision Fiber-Optic Rotational Seismometer

作　　者：李帅 杨远洪[1] 李良祯 王孺沫 Li Shuai;Yang Yuanhong;Li Liangzhen;Wang Rumo(School of Instrumentation and Optoelectronic Engineering,Beihang University,Beijing 100191,China)

机构地区：[1]北京航空航天大学仪器科学与光电工程学院,北京100191

出　　处：《中国激光》2022年第19期40-49,共10页Chinese Journal of Lasers

基　　金：国家重点研发计划(2018YFC1503703);国家自然科学基金(61227902,U1637106);创新团队发展计划(IRT1203)。

摘　　要：基于光纤陀螺(FOG)的光纤旋转地震仪(FORS)对平动不敏感,兼具低噪声、高灵敏度和便携等优点,特别适用于行星地震学中三维旋转分量的观测。基于偏光干涉理论建立了消偏FOG中Sagnac干涉仪环路(SIA)的输出光谱模型,揭示了消偏FOG的误差机理,提出并验证了在SIA中增加高频相位调制的噪声抑制技术。设计了基于差分消偏光纤陀螺的高精度FORS,研制出BHFORS-3C型三轴高精度旋转地震仪,三轴自噪声均小于4.5 nrad·s^(-1)·Hz^(-1/2)。通过长期现场观测,获得了大量地震三维旋转观测数据,并进行了模型分析和研究。研制的旋转地震仪已具备现场应用条件,为行星地震学六分量观测和地震活动的精准分析提供了重要支撑。Objective Planetary seismology is a new discipline for imaging the internal structure of planetary objects,and it shows the law of planetary motions and determines whether they are habitable.The complete internal structure of planetary objects cannot be obtained using conventional seismometers,which can only measure three translational components in the geological movements.Thus,three rotational components in the geological movements must also be measured.Nowadays,the rotational components are frequently measured using gyroscopes.Large ring laser gyroscopes are employed to achieve ultra-high precision measurement,although they can only function at a fixed site.The fiber optic rotational seismometer(FORS),which is based on the fiber optic gyroscope(FOG),is insensitive to the translation motion and has the benefits of low noise,high sensitivity,and portability,which is ideally adequate for measuring three rotational components in planetary seismology.High precision is required for the FORS,but as a civil system,low cost is also required.The biggest challenge for a practical high-precision FORS is to satisfy the demands of high performance and low cost simultaneously.In this study,the error mechanism of depolarized FOGs is shown and a noise suppression technique is proposed.Based on the differentially depolarized FOG,a three-axis high-precision seismometer(BHFORS-3C)is developed with self-noise smaller than 4.5 nrad·s^(-1)·Hz^(-1/2).Long-term seismic observations demonstrate that BHFORS-3C is ready for field application and offers crucial support for the observation of 6-component planetary seismology and the accurate analysis of seismic activities.Methods The output spectrum of Sagnac interferometer assembly(SIA)in a depolarized FOG is the modulation of the original input spectrum.The conventional analysis approach obtains the modulated output spectrum model by calculating the transfer function of the SIA.The depolarized SIA consisted of several polarization-maintaining fibers(PMFs)and single-mode fiber(SMF)coil

关 键 词：测量 光纤陀螺 旋转地震仪 行星地震学 自噪声 

分 类 号：V241.5[航空宇航科学与技术—飞行器设计]