Ultrasonic transducers which include at least one internally directed
generally concavely configured sonic energy radiating element which
directs sonic energy toward at least one arcuate energy reflecting
surface which redirects and focuses the energy through an opening in a
housing defining the transducer. The configuration of the at least one
radiating element and the at least one energy reflecting surface are such
that sound waves from substantially any point along the radiating element
to the reflecting surface and to a focus exteriorly of the opening are
substantially equal. The transducers function to focus energy either as
transmitters or receivers.