Improving Ultrasonic Imaging of Aluminum Plates using Phase Modulation
Keywords:Phase modulation, Instantaneous phase, Ultrasonic imaging, Non-destructive testing, Pearson correlation coefficient
Ultrasonic imaging using arrays is a widespread technique used in medical imaging, with increasing use in industry. Conventional techniques use amplitude information from the ultrasonic signals to produce the images. These amplitude images can be produced with high quality, but can also present limitations regarding dead zone, artifacts and detection of far reflectors. Coherence images based on the signal phase have been explored in some works, and produce an image that indicates the presence of a defect. In this work we explore he effect of phase modulation of the ultrasonic signal and its effect on the corresponding coherence image. Simulations and experimental tests in an aluminum plate using Lamb waves and a linear piezoelectric array show that the phase modulation has
advantages over coherence images without phase modulation for defect indication.