Radiated fields of ultrasonic transducer.
The sound that emanates from a piezoelectric transducer does not originate from a point but instead originates from most of the surface of the piezoelectric element, Round transducers are often referred to as pista source transducer because the sound field resembles a cylindrical mass in front of the transducer. The sound field from a typical piezoelectric transducer is shown below. The intensity of the sound in indicated by color, with tighter indicating higher indicating higher intensity. Since the ultrasound originates from a number of points along the transducer face, the ultrasound intensity along the beam is affected by constructive and destructive wave interference. These are sometimes also referred to as diffraction effects. This wave interference leads to extensive fluctuations in the sound intensity near the source and is known as the near field. Because of acoustic variation with in a near field, it can be extremely difficult to accurately evaluate flaws in material...