Comparison of Imaging Quality of Compact Rectangular Arrays Based on Laser and Piezoelectric Transducers

To improve the resolution and signal-to-noise ratio, and suppress side lobe and grating lobe, an imaging method based on phase difference of array data was proposed.The piezoelectric transducer array and the laser array were combined with amplitude imaging and sign coherence factor imaging, respectively, to detect the defects in the aluminum plate.The continuous wavelet transform was used to process the wide-band Lamb wave signal with a low time-domain resolution, which can obtain a narrow-band signal with a high time-domain resolution at a given frequency.Finally, frequency extraction signals were processed by combining the amplitude imaging technique and the sign coherence factor imaging technique, and then defect imaging was realized in the aluminum plate.The piezoelectric transducer array imaging results and laser ultrasonic array imaging results were compared.By making full use of the advantages of non-contact, point focus of the laser ultrasonic array, the artifacts can effectively be reduced so that the defects can be located more accurately.