Localisation of defects with time and frequency measurements using pulsed arrays

The frequency dependent directivity of the periodic permanent magnet transducer is used to extract information about the position of any discontinuities present in a sample. Two approaches are used: narrowband excitation and broadband pulsed generation. Simultaneous narrowband excitation, with the appropriate frequency, can be used to steer the ultrasound to a particular angle. Broadband excitation emits a wavefront that extends over a large range of angles, with the frequency of the wavefront varying smoothly as a function of angle. Using these two approaches, two-dimensional maps of any defects present in the sample can be obtained.