提高频域合成孔径超声阵列成像质量的方法

A Method for Improving the Imaging Quality of Synthetic Aperture Ultrasonic Array in Frequency Domain

随着工业制造水平的不断提升,对于工业无损检测的要求也越来越高,为了实现更快更准确的检测,基于相位迁移算法的频域合成孔径超声成像方法在实际成像检测中应用越来越多。针对该成像理论,提出一种提高成像质量的方法。首先对时域阵列检测信号,依次进行卷积滤波、波形包络提取及信号锐化处理,提高信号信噪比;然后再将这些信号进行二维傅里叶变换,并通过相位迁移算法重建声场;最后使用二维傅里叶反变换对检测区域进行逐层成像。用多缺陷试块进行检测成像实验,结果表明,经过该方法处理,成像质量得到提高,与未预处理的成像结果比较,在相同实验条件下,信噪比平均提高3.9 dB。

With the development of industrial manufacturing level,the requirements for industrial nondestructive testing are becoming higher and higher. In order to achieve faster and more accurate detection,a ultrasonic imaging algorithm of frequency domain synthetic aperture based on phase shift migration(PSM)is more and more used in practical imaging detection. A method for improving the imaging quality is proposed here according to the imaging theory. Firstly,the collected time domain array signals are processed by convolution filtering,waveform envelope analysis and signal sharpening respectively,which improved signal-to-noise ratio(SNR)of the signals. Then,the processed signals are processed with two-dimensional Fourier transform. The sound field is reconstructed with PSM. Finally,the two-dimensional inverse Fourier transform is used to image the detection area layer by layer. The imaging experiment is carried out with multi-defect specimen,and the results show that the imaging quality is enhanced with the method. Compared with the imaging results without the preprocessing method,SNR is increased by 3.9 dB on average under the same experimental conditions.