A practical water-coupled ultrasound axicon has been developed, which is realized by a combination of an annular PZT and a conical plexiglass wedge bonded to it. The acoustic beam from the PZT is refracted by the wedge and focused over a certain range in the axial direction. Two kinds of axicon are prepared for flaw examination of metals or ceramics. Suppression of the surface echo and sidelobes is discussed. Some examples which show the abilities of the axicons are also presented. © 1982.
Nagai, S., & Iizuka, K. (1982). A practical ultrasound axicon for non-destructive testing. Ultrasonics, 20(6), 265–270. https://doi.org/10.1016/0041-624X(82)90047-6