声表面波的光激发及光检测

【作者】 侯锐；

【导师】 陆建； 倪晓武；

【作者基本信息】 南京理工大学 ， 测试计量技术及仪器， 2002， 硕士

【摘要】 从固体的弹性性质和波动方程出发，阐述了声表面波的基本性质。介绍了激光超声领域的研究进展，分析了光致超声过程中，能量从光能到声能的转换，归纳了用激光激发声表面波的机理，讨论了两种主要的模型：热弹模型和融蚀模型。对于热弹模型，应用了等效力源法和格林函数法。对于融蚀模型，应用了等效力源法。 本文着重在实验上研究激光产生声表面波的检测。在比较了已有的各种测试声表面波手段的基础上，提出了基于光偏转技术的单光纤测试法，并设计完成了一套光纤光声传感器。对Nd:YAG固体激光器在铝和硅材表面激发的声表面波脉冲进行了系统的实验测试，结果得到了良好的波形，此法相对于其他光学方法具有频响高，灵敏度高，线性较好的诸多优点。而且装置简单，易于调节，由于引入了光纤，具有进一步发展的前景。更多还原

【Abstract】 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.更多还原