Biplane Phased Array for Ultrasonic Medical Imaging

We report a transducer structure tha t combines two orthogonal phased arrays which enable the real-time scanning of two orthogonal sectors. This biplane phased array is formed by partially dicing the opposite faces of a composite piezoelectric plate in orthogonal directions. Individual elements of the orthogonal arrays show broad radiation patterns close to the theoretical expectations for isolated elements. Arrays formed by patterning the electrode alone, without cross-dicing, show a narrower directivity pattern for a single element. This narrowing is a refractive effect due to the relatively high acoustic velocities in the composite material as compared to the sound velocity in the propagation medium. The concept of the biplane phased array forms the basis for a new class of transducer systems which combine two transducer arrays in a single piezocomposite plate.