Phase of ultrasonic reflection at Rayleigh angle incidence

The phase of an ultrasonic beam reflected from a liquid-solid interface at and near Rayleigh angle incidence is measured using a new technique. Results indicate that two waves comprise the reflected beam, i.e., a specularly reflected wave and a reradiated surface wave, which do not change phase as the angle of incidence varies, which maintain a 180° phase difference between them, and which propagate collinearly only at the Rayleigh angle.