Lecture 14 Flashcards
Piezoelectricity involves a
Element
Sound beam will naturally come to a
Focus
Opposite of natural focus
Electronic focus
Near zone aka
Frensel zone or near field
The near zone is the region extending
From the transducer to the minimum beam width
Beam width decreases w/ increasing _______ this is called _______
Distance from the transducer
Convergence
Far zone aka
Fraunhofer zone
Far field
The far zone is the region
That lies beyond a distance of one near zone length
Beam width increases in far zone w/ ___________ this is called ______
Increasing distance from the transducer
Beam divergence
Aperature meaning ______
Opening
Aperature is
The element size (width) for a single disk transducer/ the width of group of elements
Beam profile=
Width - wb
Beam width changes w/
Depth
Beam width affects ______ of signal at that depth
Resolution
Beam width also affext the _______of the sound beam at that depth
Intensity
Intensity is not ____ within the beam
Uniform
Power is _______ within the the beam
Uniform
At the focus
Wb=
0.5 the aperture size
Width of a disk transducer element is
1.5mm
NZL is determined by (2)
Size of the element(s) (aperture)
Operating frequency
I aperature increases NZL _____
Increases
If operating frequency increases then NZL ______
Increases
T/f there is no far zone length
T
Natural focus is at end of
Near zone
At double the NZL width =
Element width/diameter
Focal length is
Distance to the focus
Same length of near zone length
Higher frequency transducers tend to hac _____ footprints
Smaller
Smallest beam width has the strongest _______ therefore _____
Intensity
Will pick up more signals
Better _______ is given with smaller beam width
Resolution
Improved focusing resolution only occurs in the _______
Near zone
Beam width is decreased in the _______ and widens in the _________
Focal region
Region beyond
Focusing can be accomlished by (2)
Curved lens/ element
Phasing
An increase in curve of element results in
Closer focus
Curved element is a type of _______ focusing
Mechanical
