ABSTRACT This paper describes a new type of electronically scanned and focused acoustic imaging device called the cylindrical grating acoustic scanner. With this device, a new transducer called the circular-edge-bonded transducer (CEBT) is devised that is bonded on one end of a cylindrical substrate and can generate a surface acoustic wave propagating along the cylindrical surface of the substrate. An array of grooves is fabricated on the cylindrical surface of the substrate to serve as a scattering grating. The periodical grooves scatter a chirped surface-wave pulse coherently into a focused bulk-wave "ring" that scans at the surface-wave velocity. The focal length and resolution can be adjusted by changing the chirp rate and time-bandwidth product of the chirp, respectively. A 2.3-MHz circular scanner with 25-cm field of view and 2.6-mm resolution has been constructed and studied. Acoustic image of an artificial defect in an aluminum pipe is obtained.
1999 IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control Vol. 46, pp. 1068-1073, 1999
© 1999, by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved.