Abstract
This paper is concerned with the development of Ultrasonic probe for detecting near surface discontinuity. Near surface discontinuity is difficult to detect for ultrasonic testing. To detect near surface discontinuity, a leaky surface acoustic wave (LSAW) experiment is carried out. But ordinarily it is difficult to separate the LSAW and the longitudinal waves along the central axis. In this study, a hollow is made in the center of the acoustic lens, and so the separation of LSAW becomes possible. The lens is named DH (Delaying Hole) lens. To verify the effect of the lens, the delamination and crack test samples are made, and sprayed coating surface are evaluated at the condition that surface are un-machined. The results show that with this method, delamination and crack parts are clearly detected and the acoustic image near the edge parts can also be clearly obtained.
