【摘要】 针对地震勘探中横波检波灵敏度低的问题,提出了一种基于菲涅耳衍射理论的双光栅水平向地震检波器。介绍了系统的工作原理,通过使用新的人工地震动模拟函数,研究检波器力学模型运动微分方程的解和频率特性,证明了系统的可行性。推导了激光束经过双光栅系统衍射后的场分布和光强,仿真分析表明,沿接收屏纵向强度呈波形分布,利于光电信号转换,推出了条纹频率与地震动水平向速度的关系式,利用对称指示光栅提出了一种对地震动位移、速度进行辨向并记录平衡位置时间的简便方法。初步计算该检波器的灵敏度为136pm,动态范围达144dB,与其他检波器相比,对应的性能参数值提高了10%以上,有良好的工程应用前景。更多还原

【Abstract】 A new type of short-period horizontal geophone is developed for solving the low sensitivity for detecting ground motion caused by S-wave, which mainly constructed with a vibration limit pendulum and a double-grating diffraction system. The working principle of this geophone is introduced. Its feasibility is proved by analyzing the differential vibration equation and frequency characteristic of mechanical model using a new simulation function of artificial ground motion and theoretical studying the diffraction field after superposed gratings. The light intensity on receiving screen is derived by applying Fresnel diffraction theory. The horizontal velocity of ground motion is calculated through putting forward an easy way to determine the relation between fringe frequency and ground motion speed, and record the time when pendulum passes through the equilibrium position based on the symmetric indicative grating. The dynamic range and sensitivity of geophone system that uses 1800 grooves/mm gratings and 4096 fringe subdivision technique is around 144 dB and 136 pm, respectively. Compared with other kinds of geophone, the corresponding parameters of this newly system is improved at least 10%, showing its application potential in exploration engineering.更多还原