Effect of periodic surface roughness on V(z) curves for the line-focus acoustic microscope

A specimen with a periodic surface profile is considered to estimate the effect of surface roughness on the V(z) curve for the line-focus acoustic microscope. The Fourier optics approach is used to obtain the response of the lens and the Rayleigh-Fourier method is used to obtain the reflection coefficients for plane wave incidence from the fluid side on the periodic surface. An integral expression is obtained to calculate V(z) curves for periodic surface profiles. The V(z) curves are used to calculate the leaky Rayleigh wave velocities by applying the fast Fourier technique. Numerical results are presented to display the effect of sinusoidal surface roughness on the V(z) curves and the corresponding leaky Rayleigh wave velocities.