Observation of ultrasonic backward beam displacement in transmission through a solid having superimposed periodicity

摘要

The backward displacement of an ultrasonic beam on a periodically corrugated liquid-solid interface was originally observed in 1976. Additional study of the phenomenon has occurred recently, as further studies of acoustic and elastic wave interaction with periodic surfaces and structures have been driven by increasing interest in phononic crystals. Until now, the phenomenon has only been observed in reflection. This study reports results from experiments that investigate whether a backward beam displacement can also occur in transmission through the interior of a solid. The results indicate that a backward shift may in fact be observed in all fields generated. Therefore, ultrasonic backward beam displacements are not only a reflection phenomenon but may also be observed in transmission.