Haupert Sylvain, Ohara Yoshikazu, Carcreff Ewen, Renaud Guillaume
Sorbonne Université, CNRS UMR 7371, INSERM UMR S 1146, Laboratoire d'Imagerie Biomédicale, Paris, France.
Department of Materials Processing, Graduate School of Engineering, Tohoku University, 6-6-02 Aoba, Aramaki-aza, Aoba-ku, Sendai 980-8579, Japan.
Ultrasonics. 2019 Jul;96:132-139. doi: 10.1016/j.ultras.2019.02.003. Epub 2019 Feb 12.
An ultrasonic technique for imaging nonlinear scatterers, such as partially-closed cracks, buried in a medium has been recently proposed. The method called fundamental wave amplitude difference (FAD) consists of a sequence of acquisitions with different subsets of elements for each line of the image. An image revealing nonlinear scatterers in the medium is reconstructed line by line by subtracting the responses measured with the subsets of elements from the response obtained with all elements transmitting. In order to get a better insight of the capabilities of FAD, two metallic samples having a fatigue or thermal crack are inspected by translating the probe with ultrasonic beam perpendicular (i.e. parallel) to the crack direction which is the most (i.e. less) favorable case. Each time, the responses of the linear scatterers (i.e. conventional image) and nonlinear scatterers (i.e. FAD image) are compared in term of intensity and spatial repartition. FAD exhibits higher detection specificity of the crack with a better contrast than conventional ultrasound imaging. Moreover, we observe that both methods give complementary results as nonlinear and linear scatterers are mostly not co-localized. In addition, we show experimentally that FAD resolution in elevation and lateral follows the same rule as the theoretical resolution of conventional ultrasonic technique. Finally, we report that FAD gives the possibility to perform parametric studies which let the opportunity to address the physical mechanisms causing the distortion of the signal. FAD is a promising and reliable tool which can be directly implemented on a conventional open scanner ultrasound device for real-time imaging. This might contribute to its fast and wide spread in the industry.
最近提出了一种用于对埋于介质中的非线性散射体（如部分闭合裂纹）进行成像的超声技术。这种称为基波幅度差（FAD）的方法包括针对图像的每一行使用不同的元件子集进行一系列采集。通过从所有元件发射时获得的响应中减去用元件子集测量的响应，逐行重建揭示介质中非线性散射体的图像。为了更好地了解FAD的能力，通过将超声束垂直（即平行）于裂纹方向移动探头来检测两个具有疲劳或热裂纹的金属样品，这是最（即最不）有利的情况。每次，从强度和空间分布方面比较线性散射体的响应（即传统图像）和非线性散射体的响应（即FAD图像）。与传统超声成像相比，FAD对裂纹具有更高的检测特异性和更好的对比度。此外，我们观察到这两种方法给出互补的结果，因为非线性和线性散射体大多不在同一位置。另外，我们通过实验表明，FAD在仰角和横向的分辨率遵循与传统超声技术的理论分辨率相同的规律。最后，我们报告FAD使得进行参数研究成为可能，这为研究导致信号失真的物理机制提供了机会。FAD是一种有前途且可靠的工具，可直接在传统的开放式扫描仪超声设备上实现实时成像。这可能有助于其在行业中的快速广泛应用。
