Focusing by using a lens to converge sound is an example of which focusing type?

Focusing by using a lens to converge sound is an example of which focusing type?

• A. Dynamic focusing
• B. External focusing
• C. Internal focusing
• D. Phased array focusing

Answer: (B)

External focusing uses a physical lens placed in front of the transducer to bend the sound waves and converge them to a focal point inside the body. The lens’s shape and material determine where the focus occurs, so the beam is concentrated at a specific depth without relying on the transducer’s active elements or electronic timing. This is different from internal focusing, which relies on the transducer’s own curved surface or array geometry to shape the beam, and from dynamic or phased array focusing, which use electrical delays to adjust focus at different depths or steer the beam.

External focusing uses a physical lens placed in front of the transducer to bend the sound waves and converge them to a focal point inside the body. The lens’s shape and material determine where the focus occurs, so the beam is concentrated at a specific depth without relying on the transducer’s active elements or electronic timing. This is different from internal focusing, which relies on the transducer’s own curved surface or array geometry to shape the beam, and from dynamic or phased array focusing, which use electrical delays to adjust focus at different depths or steer the beam.