Average longitudinal size of ultrasonic speckles back-scattered from an interface

Summary

The average longitudinal size of ultrasonic speckles back-scattered from a rough interface is investigated theoretically and experimentally in this paper. When a rough interface is insonified by ultrasound pulses, the average longitudinal size of the speckles in the space is found to be related not to the spatial coherence but to the temporal coherence of the ultrasound waves on the interface. Further theoretical analysis shows that the average longitudinal size of speckles is dependent on the sound speed and the time duration of the ultrasound pulse incident on the interface. To verify this theoretical conclusion, experiments are performed with a special experimental set-up. The experimental results are in good agreement with the theoretical ones.