Focused Transducer : A transducer with a concave face which converges the acoustic beam to a focal point or line at a definite distance from the face. (RP 2X)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}