With fixed focusing techniques, which two aspects cannot be changed?

With fixed focusing techniques, which two aspects cannot be changed?

• A. Focal depth and Range
• B. Extent of focusing and Aperture
• C. Focal depth and Extent of focusing
• D. Focal length and Beam width

Answer: (C)

When focusing is fixed, the beam is designed to have a single, unchanging focus configuration. The two things that are locked in by that design are the focal depth—the distance from the transducer to the center of the focus—and the extent of focusing, which is the length of the focal zone over which the beam stays brought to a tight focus. Since these are determined by the transducer’s geometry and lensing, they don’t change during imaging. To alter them, you’d need a different transducer or a mode that provides dynamic focusing. In other words, the visible, unchanging factors are how far away the focus sits and how long the focal region lasts. Other parameters like imaging depth range, or adjustments to aperture or beam characteristics, aren’t governed by fixed focusing in the same way and can differ with settings or hardware changes.

When focusing is fixed, the beam is designed to have a single, unchanging focus configuration. The two things that are locked in by that design are the focal depth—the distance from the transducer to the center of the focus—and the extent of focusing, which is the length of the focal zone over which the beam stays brought to a tight focus. Since these are determined by the transducer’s geometry and lensing, they don’t change during imaging. To alter them, you’d need a different transducer or a mode that provides dynamic focusing.

In other words, the visible, unchanging factors are how far away the focus sits and how long the focal region lasts. Other parameters like imaging depth range, or adjustments to aperture or beam characteristics, aren’t governed by fixed focusing in the same way and can differ with settings or hardware changes.