Abstract: An endoscope, especially for transesophageal echocardiography. An encapsulated ultrasonic transducer capsule is provided having a self-contained electro-mechanical sector scanner. A sealed housing is formed which includes axially aligned tubular sections, one of magnetic material and the other of acoustically transparent plastic. A tubular shaft is journalled axially within the housing for limited sector scanning rotation. A magnetic rotor is fixed to the shaft for operation within the magnetic housing section and a transducer element is fixed to the shaft within the other tubular section. Conductor wires for activating the transducer are fixed at one end of the capsule and extend axially through the tubular shaft for connection to the transducer. Position sensing means are incorporated within the capsule. The construction enables the capsule to be highly miniaturized and greatly improved relative to known devices of its type.