EXPERIMENTAL-STUDY OF INHOMOGENEOUS WAVE REFLECTION FROM A SOLID-AIR PERIODICALLY ROUGH BOUNDARY USING LEAKY RAYLEIGH-WAVES

In this paper a leaky Rayleigh wave is used as a source generating an exponentially decaying (along the wave front) inhomogeneous wave in a fluid. The inhomogeneity of the leaked wave beam profile is measured e xperimentally and compared with that predicted from the theoretically calculated imaginary part of the leaky Rayleigh wave number. The excit ed inhomogeneous wave is incident normally upon an aluminum sample wit h a rough back surface. The rough surface is isolated by a gap from th e immersing liquid. The reflection of this wave from a solid-air bound ary of periodic sawtooth profile is studied. The frequency spectrum of the wave reflected from such an aluminum-air rough surface is measure d and a sharp dip in the spectrum is observed which can be attributed to the excitation of a Rayleigh wave along the rough surface. Good agr eement is obtained between experimental data and inhomogeneous plane w ave theory.