Ultrasonic Field And Resolution Flashcards
What is divergence?
The spreading out of a sound wave from a small source
Near fields have this kind of beam ____________(uniform or non-uniform) as a result of ___________________.
Non-uniform; interference
True/False: There is more chaos in the ultrasound waves as they travel down.
False.
Chaos is highest at the initial point, and as the beam travels, the wavefront becomes more uniform due to Huygen’s principle and the wavelets.
This is what off-axis beams are called.
Grating lobes (or side lobes)
In mechanical lobes, grating lobes are called ______________
Side lobes.
Grating lobes are the result of _________________
Length and width vibration of the crystal resulting in crosstalk.
Side lobes are the result of _______________
Radial mode vibration.
Fresnel is the _________________
Fraunhofer is the _______________
Near field ; Far field
In flat disc probes, there is a narrow of the beam that occurs at _____________, this is also called the ________________.
One near field length ; Transition zone
At the transition zone, the beam is equal to what?
1/2 Diameter of the crystal.
The principle that states that each point of crossing in waves is considered a point source or new wave that produces spherical secondary waves is called ____________________
Huygen’s Principle
Wave fronts produced from a sound source whose diameter is equal to one wavelength will have regions of compressions and rarefactions and create a ________________ beam.
Non-uniform.
Formula for Near zone length.
[(D^2) x F )] / 6
Interference that occurs from a transducer face creates what 2 distinct areas of the sound beam?
Near field and far field
The near field extends from what to what?
Transducer face to the focal point
