Anatomy of a Sound Beam
The location where the beam is the narrowest.
What is focus/focal point?
Diameter of sound beam at the transducer.
Characteristics of a fixed focus transducer than determine the focal depth.
What is:
Transducer diameter and frequency
Define beam divergence.
What is the gradual spread of the ultrasound beam in the far field?
What is
end of the near zone
beginning of the far zone
middle of the focal zone?
Diameter of the sound beam of the focus.
What is 1/2 transducer diameter?
Relationship between transducer diameter and focal depth.
What is directly related?
Ex: larger diameter PZT = deeper focus
smaller diameter PZT = shallower focus
What is transducer diameter and frequency?
What is converges and diverges?
What is beam diameter equals transducer diameter?
What is a direct relationship?
Ex: higher frequency = deeper focus
lower frequency = shallower focus
Type of diameter crystal that diverges more in the far zone.
Synonymous names for near zone and far zone
What is
near zone: Fresnel zone
far zone: Fraunhofer zone
Diameter of the sound beam deeper than 2 near zone lengths.
What is beam diameter is wider than transducer diameter?
which of the following probes creates a beam with the deepest focus?
6mm diameter, 8MHz
5mm diameter, 5MHz
What is 6mm diameter, 8MHz
Larger diameter crystals (improve or degrade) lateral resolution in the far field.
What is improve lateral resolution?
Explanation: larger diameter crystals diverge less in the far field than smaller diameter crystals.
What is:
1. focus
2. near zone
3. focal length
4. far zone
5. focal zone
True or False: wavelength and near zone length are inversely related.
Explanation: shorter wavelength = Higher frequency. Higher frequency = longer near zone length.
Divergence is minimized with a ______ diameter and _____ frequency transducer.
What is larger diameter and high frequency?