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对于低频激发的液体表面波,提出了一种激光干涉测量方法,并在实验上观察到了清晰的干涉图样,且干涉条纹定域在一定的空间范围。当表面波激发源频率为几十赫兹时,其表面波参数稳定不变,且表面波反射光所形成的干涉图样稳定不变;而当表面波激发源频率为几赫兹至亚赫兹频段时,表面波为调幅波。表面波反射光所形成的干涉条纹的定域宽度周期性振荡,振荡频率与激发频率相同。理论上导出了调制干涉图样光强度与表面声波之间的解析关系,并得到了干涉条纹间隔与表面波波长、干涉条纹定域宽度与表面波振幅之间的解析关系。
For low frequency excited liquid surface wave, a laser interferometry method is proposed, and a clear interference pattern is observed experimentally, and the interference fringes are localized in a certain spatial range. When the excitation frequency of the surface wave is several tens of hertzs, the surface wave parameters are stable, and the interference pattern formed by the reflected light of the surface wave is stable. When the excitation frequency of the surface wave is in the frequency range of several hertz to the subhertz, Surface wave amplitude modulation wave. The localized width of the interference fringes formed by surface wave reflected light periodically oscillates with the same oscillation frequency as the excitation frequency. The analytical relationship between the intensity of the modulated interference pattern and the surface acoustic wave is derived theoretically and the analytical relationship between the interference fringe spacing and the surface wavelength, the localized width of the interference fringes and the surface wave amplitude is obtained.