Spatial apodisation using modular composite structures

A method that utilizes the unique properties of ceramic-epoxy-composite transducers is presented. The manufacture and evaluation of a modular, rectangular composite transducer, in which the volume fraction reduces from the center outward in a controlled manner, is described. Because output pressure is a direct function of volume fraction, transmission beam shading can be achieved in a relatively straightforward manner. Results illustrating the expected improvement in beam characteristics are presented. These are shown to compare favorably with theoretical expectations. >