A miniaturized ultrasonic probe includes a housing encasing a motor, an ultrasonic transducer mounted for controlled rotation on the motor shaft, and an angular position sensor connected to the shaft. The housing has a radiating dome about the transducer and is sealed and wholly filled with an acoustically-transparent...http://www.google.es/patents/US5195519?utm_source=gb-gplus-sharePatente US5195519 - Miniaturized mechanically-steerable ultrasonic probe
