Diffraction Waves in Ultrasonic Testing

Matters of interaction between an emitted elastic wave with reflector and a received signal are considered. Distinctive features and restrictions of the geometrical optics method against the method based on the geometrical theory of diffraction are also examined.
The descriptions of TOFD (ultrasonic time-of-flight-diffraction) method and of its brother delta method are given. The experience of using arrays with prisms for generation of different wave types is of interest.