Apparatus for the pulse-echo ultrasonic examination of an object comprised of transducer means for transmitting pulses of ultrasonic energy and receiving reflected echoes of said pulses immersed in a coupling medium contained within a housing, the pulses being transmitted and echoes received through...http://www.google.co.uk/patents/US4094306?utm_source=gb-gplus-sharePatent US4094306 - Apparatus for ultrasonic examination
