BEAM STEERING WITH PULSED 2-DIMENSIONAL TRANSDUCER ARRAYS

Two-dimensional (2-D) transducer arrays offer the potential for producing symmetrically focused ultrasound beams that can be steered throughout a three-dimensional (3-D) volume. The major problem facing the development of 2-D arrays for imaging is the complexity arising from the large number of elements anticipated in such transducers. We have undertaken a theoretical investigation of the focusing and steering properties of pulsed 2-D arrays to characterize the parameters required for medical imaging, such as element size, spacing and number of elements. Details of the computational methods employed are presented in this paper, as well as a discussion of the steered beam properties of wideband 2-D arrays. The effects of apodization and element cross-coupling on the beam properties of a 2-D transducer array are examined. Finally, we discuss the beam properties of various sparse arrays having elements randomly distributed over the aperture of the transducer.