Feasibility study on surface temperature depth profiling by surface acoustic wave spectroscopy

本文从理论上和实验上对表面声波（SAW）光谱法进行表面温度深度剖面分析的可行性进行了研究。首先，从理论上证明，对于许多工业材料来说，要使材料表面有一个陡峭的温度梯度来受热似乎是困难的。在先验信息的基础上，采用数值模拟而非实验方法验证了声表面波表面温度深度剖面的可行性。结果表明，虽然表面温度梯度可以由声表面SAW色散来确定，但用常规超声仪器测量的实验数据来定量确定是非常困难的。这主要是由于现有仪器中超声波信号的测量不确定度。幸运的是，超声脉冲回波技术具有有效的反演方法，当材料表面附近的温度梯度是渐变的时，可以提供合适的表面温度深度剖面。

In this work, feasibility study on surface temperature depth profiling by surface acoustic wave (SAW) spectroscopy has been made theoretically and experimentally. At first it has been demonstrated theoretically that it seems difficult for many of industrial materials to have a steep temperature gradient in which the material surface is being heated. Based on the prior information, numerical simulations rather than experiments are performed to examine the feasibility of surface temperature depth profiling by SAW. The results show that although surface temperature gradient might be able to be determined from SAW dispersion, it must be very difficult to realize such quantitative determination with experimental data measured using a conventional ultrasonic instrumentation. This is basically because of measurement uncertainty in ultrasonic signals of the present apparatus. It is fortunately demonstrated that ultrasonic pulse-echo technique with an effective inversion method provides an appropriate surface temperature depth profiling if the temperature gradient near material surface is gradual.