Using phase information to enhance speckle noise reduction in the ultrasonic NDE of coarse grain materials
Using phase information to enhance speckle noise reduction in the ultrasonic NDE of coarse grain materials
复制标题
利用相位信息增强粗晶材料超声无损检测中的散斑噪声抑制
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. Gachagan
中科院分区：
文献类型：
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作者：
T. Lardner;Minghui Li;A. Gachagan
具有粗晶结构的材料由于其对应力和腐蚀的抵抗力而在工业中变得越来越普遍。这些材料很难用超声波检查，因为颗粒的反射会导致高噪声水平，从而阻碍感兴趣的回波。空间平均子孔径相关成像（SASACI）是一种先进的阵列波束形成技术，利用阵列子孔径图像之间的互相关性来生成图像加权矩阵，以降低噪声水平。本文提出了一种受 SASACI 启发的方法，利用相位信息来进一步改进成像，以改进聚焦并减少噪声。来自相邻阵列元素的 A 扫描使用信号幅度和相位进行互相关，以改进延迟定律并最小化相位畸变。基于相位和基于幅度的校正图像用作二维互相关算法的输入，该算法将输出可应用于任何传统图像的加权矩阵。该方法使用 5MHz 阵列和粗粒 Inconel 625 阶梯楔块进行了实验验证，并与全聚焦方法 (TFM) 进行了比较。初步结果表明，与 TFM 相比，SNR 提高了 20dB 以上，分辨率也更高。
Materials with a coarse grain structure are becoming increasingly prevalent in industry due to their resilience to stress and corrosion. These materials are difficult to inspect with ultrasound because reflections from the grains lead to high noise levels which hinder the echoes of interest. Spatially Averaged Sub-Aperture Correlation Imaging (SASACI) is an advanced array beamforming technique that uses the cross-correlation between images from array sub-apertures to generate an image weighting matrix, in order to reduce noise levels. This paper presents a method inspired by SASACI to further improve imaging using phase information to refine focusing and reduce noise. A-scans from adjacent array elements are cross-correlated using both signal amplitude and phase to refine delay laws and minimize phase aberration. The phase-based and amplitude-based corrected images are used as inputs to a two-dimensional cross-correlation algorithm that will output a weighting matrix that can be applied to any conventional image. This approach was validated experimentally using a 5MHz array a coarse grained Inconel 625 step wedge, and compared to the Total Focusing Method (TFM). Initial results have seen SNR improvements of over 20dB compared to TFM, and a resolution that is much higher.