低频液体表面波衍射条纹正负级次的不应性

The Non-correspondence of Diffraction Patterns of Positive and Negative Grade from Low-frequency Liquid Surface Waves

基于声光衍射原理,利用光学方法对低频液体表面波的光衍射特性进行了研究,给出了非对应级数的解析表达式并进行了数值模拟,解释了非对应分布的机理.实验观察到清晰、稳定的衍射图样,且条纹间距具有明显的不对称性;随入射角度增大,正负级衍射条纹具有明显的不对应分布,即正条纹级数多于负条纹级数.研究表明:衍射条纹级数的不对应程度与入射角有关,随入射角的增大,正负级数不对应程度加剧;负级衍射条纹级数存在最大值,超过该最大值的负级衍射条纹缺失;理论分析和实验结果吻合较好.

Based on the acousto-optlc aliiraction theory,the light characteristics of low-frequency liquid surface waves was investigated using the method of optical. An expression was given about the non-corresponding orders, the analytical expression was simulated by means of the numerical method, which explains the mechanism of the non- correspondence effect. In experiment, the steady and visible diffraction pattern was observed, and the fringe spacing has obvious asymmetry. With the increasing of incident angle, the distinct non-correspondence of the positive and negative diffraction orders is found. The number of the positive diffraction pattern is more than the negative one. The results show that： the non- correspondence effect is related to the incident angle. With the increasing of incident angle, the non-correspondence effect is more obvious. The negative diffraction order has maximum. For the orders exceeding this value, the negative diffraction pattern disappeared. It shows that the theoretical analysis agrees with the experimental result well.