Sound Beams Flashcards
What is the term for the location where the beam is the narrowest?
Focus
Also known as the focal point.
What is defined as the region from the transducer to the focus?
Near Zone
Also referred to as the near field or Fresnel zone.
What is the distance from the transducer to the focus called?
Focal Length
This is also known as the focal depth or near zone length.
What region starts at the focus and extends deeper, where the beam diverges?
Far Zone
Also known as the far field or Fraunhofer zone.
What is the term for the region around the focus where the beam is relatively narrow?
Focal Zone
Best images are acquired in this region.
What is the term for the narrowing of the sound beam?
Convergence
This occurs as the beam travels toward the focus.
What is the term for the widening or spreading out of the sound beam?
Divergence
This occurs after the focus in the far zone.
What technology uses an adjustable focus or multiple foci?
Phased Array
This allows for better control of the beam.
What are V-shaped waves created by tiny pieces of PZT called?
Spherical Waves
Also known as diffraction patterns or Huygen’s wavelets.
What principle explains that a large active element can be thought of as millions of tiny sound sources?
Huygens’ Principle
It describes the shape of an imaging transducer’s emitted sound beam.
What is the focal depth inversely related to?
Wavelength
As wavelength increases, focal depth decreases.
What factors affect focal depth for a fixed focus transducer?
Beam Diameter & Frequency
Larger diameter and higher frequency lead to deeper focal depth.
Fill in the blank: The region that starts at the focus and extends deeper is known as the _______.
Far Zone
True or False: Higher frequency improves lateral resolution in the far field.
True
What beam diameter equals the transducer diameter?
Beam Diameter = Transducer Diameter
This is true for a fixed focus transducer.
