激光和压电传感器密集型矩形阵列成像质量的比较分析

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

    • 摘要: 为了能够提高分辨率和信噪比, 抑制旁瓣和栅瓣, 提出了一种基于阵列数据相位差的成像方法.将压电传感器阵列和激光阵列分别与幅值成像和符号相干因子成像相结合对铝板中缺陷进行检测研究.采用连续小波变换对宽频带、低时域分辨率的激光Lamb波信号进行处理, 得到特定频率下具有高时域分辨率的窄带信号.最后, 结合幅值成像技术和符号相干因子成像技术对特定频率提取后的信号进行处理, 实现铝板中缺陷的成像和定位.压电传感器阵列成像结果和激光阵列成像结果对比表明:充分利用激光阵列非接触、点聚焦的优点, 能够有效地减少赝像, 使得缺陷定位更加准确.

       

      Abstract: 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.

       

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