Ultrasound Transducers

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Ultrasound Transducers

• Design and Application

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Definitions

• Any device that converts one form of energy into
  another
• Piezoelectric effect

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Piezoelectric Materials

• Natural quartz, tourmaline
• Synthetic PZT
• Curie Point temperature at which dipolar
  elements may move freely.

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Piezoelectric Properties

• ISOTROPIC symmetrical molecular structure.

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Piezoelectric Properties

• ANISOTROPIC asymmetrical molecular structure.
  Produces a charge when deformed or a deformation
  when charged.

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Piezoelectric Properties

• ANISOTROPIC asymmetrical molecular structure.
  Produces a charge when deformed or a deformation
  when charged.

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The Real Thing!
Schlieren Photograph
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Transducer Construction
Electrical Connectors
Damping Material
Piezoelectric Ceramic
Matching Layers
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Frequency Bandwidth

• Range of frequencies present in ultrasound beam
• Difference between highest and lowest frequencies

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Q Factor

• Quality factor
• Measure of cleanness of beam

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Beam Geometry

• Crystal diameter
• Frequency bandwidth
• Attenuation
• Velocity in medium
• Huygens principle

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Divergence
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Huygens Principle
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Central Beam
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Zones
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Boundary zones
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Boundary zones
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Boundary zones
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Axial Resolution

• The ability to discriminate two point reflectors
  along the axis of the ultrasound beam.

Pulse length
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Axial Resolution
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Axial Resolution
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Lateral Resolution

• The ability to discriminate between two point
  reflectors perpendicular to the ultrasound beam
  axis.

Beam width
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Lateral Resolution
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Lateral Resolution
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Lateral Resolution