Determination of the surface wave dispersion of a coating excited by laser

A detailed study is undertaken to analyze the dispersion characteristics of a coating under laser excitation. The surface wave dispersion is one of its inherent properties. Two-dimensional Fourier transform is applied to convert the experiment data in the time-space domain into the frequency-wave-number domain, where the peaks form the dispersive curves. A coherent method is proposed to precisely measure the dispersive curves of coatings. The use of the phase information and magnitude spectrum makes the measurements more precise and stable than traditional non-coherent methods. Additionally, storage depth of oscilloscope affects the precision of dispersion curves. The technique of obtaining the dispersive curves with high precision is an efficient tool to solve the inversion problem.