Statistical properties of P-SV mode conversional ultrasonic speckles reflected from an interface

The statistical properties of the mode conversional SV wave speckles in the back scattering space were studied as ultrasonic P waves were incident on a strongly scattering interface. Based on the Frensel-Huygens theory and the correlation principle, the Rayleigh distribution of the SV wave speckle amplitude and the formula for calculating the average transverse size of the SV wave speckles were obtained. Besides, the probability density function of the normalized intensity of the SV wave speckles received by a transverse wave probe with an aperture of some size was deduced. The probability density function was related to the average number of the speckles received by the probe. Two transverse wave probes with apertures in different size were used to measure the sound intensity of the SV wave speckles in the experiment. After the experimental data of the speckle intensity were analyzed statistically, it was shown that the experimental results were in good agreement with the theoretical ones. Thus, the theoretical conclusion described above was proved to be correct.