【摘要】 为了探测水下低频声源的深度,基于声光衍射效应及润湿效应建立了可升降的光学探测系统。实验中,在自然水面放置一个铝制圆柱体,由于润湿效应导致被测液体表面发生弯曲,从而使水下低频声信号传播到水-空界面产生液体表面波。当激光斜入射到液面时,表面波对其进行振幅和相位调制,实现低频声波的声光衍射,实验上可观察到清晰、稳定的衍射图样。结果发现:改变声源深度,可得到不同声源深度的衍射图样。理论上得到了经表面波调制后衍射光场分布的表达式,基于对衍射图样的分析,推导出表面波振幅的解析式。对不同深度下声源激发产生的表面波振幅进行数值拟合,得到表面波振幅与声源深度的解析关系式,发现表面波振幅随声源深度的增加而减小,从而实现了对声源深度的探测。更多还原

【Abstract】 In order to detect the depth of the low-frequency underwater sound source,an adjustable detection system based on acousto-optic diffraction and the wetting effect was set up.A aluminum cylinder was placed in the surface of natural water.Due to wetting effect the liquid surface was curved,so that the underwater acoustic signal was able to transmit to the water-air interface generating surface acoustic wave(SAW).The amplitude and phase of incident layer beam will be modulated by SAW,and diffraction pattern appears.Thus,acousto-optic diffraction of low frequency underwater acoustic signal was achieved.Diffraction pattern is clear and stable.Changing the depth of the sound source,diffraction patterns are different.Theoretically,by analyzing the relative intensity distribution of the diffraction patterns,the amplitude of surface acoustic wave can be calculated,and the analytic expression of surface wave amplitude was derived.By fitting the relationship between surface wave amplitude and the depth of the sound source,the expression formula was given mathematically.It is can be found that the surface wave amplitude decreases with the increase of sound source.更多还原