| From the elastic property of solid and wave equation, the surface acoustic wave has been introduced. The progress of laser ultrasonics has been discussed especially for the laser-generated surface acoustic wave. The transform process of energy from light to ultrasonic has been analyzed. The generation mechanism of laser-generated surface acoustic wave has been discussed in detail excluding thermo-elastic mode and illumination mode.The emphasis of this paper is research on the detection of laser-generated surface acoustic wave. On the basis of comparing present detection techniques, we propose a new optical beam deflection technique with a single fiber. The correspond fiber sensor has been completed. With Nd:YAG laser, the surface acoustic wave pulses were generated on the sample of aluminium and silicon. Well-defined waveforms have been acquired. The results show this technique have advantages such as high frequency responding, high signal-to-noise ratio. The setup is simple and easy to adjust. Furthermore, as fiber has been used here, the technique has a promising potential. |
