Eliminating backwall effects in the phased array imaging of near backwall defects.
Eliminating backwall effects in the phased array imaging of near backwall defects.
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DOI：
10.1121/1.5051641
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发表时间：
2018-08
期刊：
影响因子：
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通讯作者：
Chao Zhang;P. Huthwaite;M. Lowe
中科院分区：
文献类型：
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作者：
Chao Zhang;P. Huthwaite;M. Lowe
超声阵列成像被广泛用于提供高质量的缺陷检测和表征。然而，目前的成像技术在检测和表征面向阵列的表面附近的缺陷方面很差，因为从缺陷散射的信号和来自平面后壁的强反射将在时域和频域两者中重叠，从而掩盖了缺陷的存在。针对这一问题，本文探讨了消除后壁反射引起的强伪影的成像算法和相关方法。本文选用半跳全聚焦法、因子分解法和时域采样法作为成像算法。然后，三种方法，称为全矩阵捕获（FMC）减法，加权函数滤波，截断方法，被开发来消除或过滤所造成的强后壁反射的影响。这些方法可以很容易地应用于很少的调整参数或很少的先验知识。仿真和实验结果验证了所提出的成像技术的性能，结果表明，所开发的方法，以消除后壁缺陷附近成像时，由后壁反射造成的伪影的有效性。
Ultrasonic array imaging is widely used to provide high quality defect detection and characterization. However, the current imaging techniques are poor at detecting and characterizing defects near a surface facing the array, as the signal scattered from the defect and the strong reflection from the planar backwall will overlap in both time and frequency domains, masking the presence of the defect. To address this problem, this paper explores imaging algorithms and relevant methods to eliminate the strong artefacts caused by the backwall reflection. The half-skip total focusing method (HSTFM), the factorization method (FM) and the time domain sampling method (TDSM) are chosen as the imaging algorithms used in this paper. Then, three methods, referred to as full matrix capture (FMC) subtraction, weighting function filtering, and the truncation method, are developed to eliminate or filter the effects caused by the strong backwall reflection. These methods can be applied easily with few tuning parameters or little prior knowledge. The performances of the proposed imaging techniques are validated in both simulation and experiments, and the results show the effectiveness of the developed methods to eliminate the artefacts caused by the backwall reflections when imaging near backwall defects.