Saw Excitation And Optical Detection

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.