对于低频微幅的液面波动,提出了一种激光干涉测量方法。实验上观察到了清晰、稳定的激光干涉图样。干涉图样受到调制, 光强在两边界位置达到极大,形成两个极亮条纹。干涉条纹被限制在两个极亮条纹之间的确定区域内。根据光干涉理论推导出了调制干涉条纹光强度、相邻条纹角宽度、干涉区域角宽度与液面波物理参量之间的解析关系, 该理论分析与实验数据吻合。

A simple setup for measuring small amplitude liquid surface wave at low frequency is designed. The high visibility and stable laser interference fringes from the liquid surface wave are gathered experimentally. The interference fringes are confined within a certain space range and the double brightest spots locate at the both boundaries of this range. Both the light intensity expression and the angularwidth of the interference fringes with the small amplitude liquid surface wave are derived theoretically, and the angle width range of the interference pattern is obtained at the same time. The theory predications accord with experimental dates well. Based on this study, a practical technique is developed to measure the physical quantities of small amplitude liquid surface wave at low frequency.