Visualization of low-frequency liquid surface acoustic waves by means of optical diffraction

A technique for low-frequency liquid surface acoustic wave (LFLSAW) visualization is developed based on the light diffraction. The technique is capable of real-time characterization of wave amplitude, and it produces highly visible stationary diffraction pattern for a low-frequency wave (a few hundreds Hz). The disappearance of the zero-order diffraction fringe, which corresponding to the 100% diffraction efficiency, was experimentally observed for using this technique. The correlation of the diffraction pattern to the LFLSAW amplitude is also experimentally established.