Huygens’ principal governs the interaction of ultrasound waves with discontinuities.
- According to Huygens’ principal, when an ultrasound wave travels through a material and encounters a discontinuity, part of the energy of the wave is reemitted by the surface of the discontinuity
- The reemission of energy is multidirectional at the tips of the discontinuity
- Thus, when an ultrasound wave encounters a discontinuity, the result is a reflected wave and two tip waves
The tip waves are called tip diffractions.