Determination of the focus zone

Principle
For the characterisation of round ultrasonic probes (piston-type transducers), the near-field length is an important quantity. It forms the zone of focus of an ultrasonic probe, in which the lateral resolving power has a maximum.
In this experiment, the sound pressure amplitudes of two ultrasonic probes are measured along the sound propagation axis with the aid of a simple ultrasonic hydrophone. The resulting measurement curves are then used to determine the near-field length of the ultrasonic probes, and these values are compared to the calculated probe values.

Tasks:

1. Measure the relative sound pressure distribution along the acoustic axis for a 1-MHz-probe and for a 2-MHz-probe.
   
2. Determine the zone of focus for each of the probes with the aid of the resulting measurement  
   curves.
   
3. Calculate the near-field lengths of the two probes and compare them to the corresponding valu
   es concerning the zones of focus resulting from the measurement curves.

Related topics

• Sound velocity
• wavelength
• Huygens principle
• interference
• near field
• far field
• zone of focus
• near-field length
• hydrophone
  

Documentation language: ENG

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