An ultrasonic sector-scan probe comprises at least an array having a plurality of ultrasonic transducer segments, a window for transmitting and receiving ultrasonic waves and an ultrasonic wave propagation medium filled in a front space between the array and the window. A group of the ultrasonic transducer...http://www.google.es/patents/US4570488?utm_source=gb-gplus-sharePatente US4570488 - Ultrasonic sector-scan probe
