Laser-excited surface acoustic wave (LSAW) techniques can realize the measurement of surface properties through dispersion curve inversion. In addition to the conventional phase spectrum method, time-frequency analysis can also be used as a calculation tool for the dispersion curve. An accurate time-frequency analysis method is important in precisely inverting the surface properties. In this paper, synchrosqueezing transform (SST) is applied to the analysis of LSAW. By comparing the processing results of the constructed LSAW signal, SST shows higher time-frequency resolution and robustness than other common time-frequency analysis algorithms. Finite element model is used to simulate the propagation of LSAW in the film/substrate structure. And SST is used to calculate the dispersion curve of SAW information extracted during the simulation. A fast algorithm is introduced, where the film thickness is initially estimated by calculating the midrange. Through inversion, the resulting film thickness error is only 1.20% from the theoretical value. Therefore, SST is an effective tool for analyzing LSAW and calculating its dispersion curve.

中文翻译：

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基于同步挤压变换的激光激发表面声波时频分析

激光激发表面声波（LSAW）技术可以通过色散曲线反演实现表面特性的测量。除了常规的相位谱法，时频分析也可以作为色散曲线的计算工具。准确的时频分析方法对于精确反演表面特性很重要。本文将同步压缩变换（SST）应用于LSAW的分析。通过对比构建的 LSAW 信号的处理结果，SST 显示出比其他常见的时频分析算法更高的时频分辨率和鲁棒性。有限元模型用于模拟 LSAW 在薄膜/基板结构中的传播。SST用于计算仿真过程中提取的SAW信息的色散曲线。引入了一种快速算法，其中薄膜厚度最初是通过计算中值来估计的。通过反演，得到的膜厚误差与理论值仅相差1.20%。因此，SST 是分析 LSAW 并计算其色散曲线的有效工具。