根据表面波声光效应的原理,提出了一种低频水下声信号的激光探测技术,并建立了实验装置。在几十赫兹的低频段,对水下声源所产生的表面声波进行了探测。实验过程中,利用MATLAB软件对拍摄的衍射图样进行扫描分析,得到了衍射图样中条纹的像素差。根据波长与条纹间距的解析关系式,得到了低频液体表面声波波长,其大小在毫米量级。利用计算机编程,根据最小二乘法拟合色散关系的回归曲线,测量结果与理论色散关系吻合。该方法具有实时、非接触的特点。

According to the principle of the surface acoustic wave (SAW) effect, a technology has been developed to detect the low-frequency underwater acoustic signal by laser and a detection apparatus is developed. In dozens of Hertz low-frequencies, the surface wave produced by the underwater acoustic was detected. In the measurement process, the diffraction pattern was scanned by using MATLAB to analyze. Then the diffraction pattern pixel of stripe was obtained. According to the analytic formula of the wavelength and stripe space, the low-frequency liquid surface wavelength with millimeter order was obtained. By using computer programming, the regression curve was fitting according to the principle of least square method. Measurement results agree with the theoretical dispersion relationship. The method has the characteristics of real-time and non contact.