Bevington P, Gartman R, Chalupczak W
National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
Rev Sci Instrum. 2019 Jan;90(1):013103. doi: 10.1063/1.5053959.
Non-destructive inductive testing of defects in metal plates using the magnetic resonance signal of a radio-frequency atomic magnetometer is demonstrated. The shape and amplitude of the spatial profile of the signal features, which represent structural defects, are explored. By comparing numerical and experimental results on a series of benchmark aluminium plates, we show correspondence between the properties of the secondary field and those of the magnetometer signal. In particular, we show that two components of the secondary field are mapped onto the amplitude and phase of the atomic magnetometer signal. Hence, a magnetic field measurement with the atomic magnetometer, although scalar in its nature, provides semi-vectorial information on the secondary field. Moreover, we demonstrate a robust process for determining defect dimensions, which is not limited by the size of the sensor. We prove that the amplitude and phase contrast of the observed profiles enables us to reliably measure defect depth.
展示了利用射频原子磁力计的磁共振信号对金属板中的缺陷进行无损感应检测。探索了代表结构缺陷的信号特征空间分布的形状和幅度。通过比较一系列基准铝板的数值和实验结果，我们展示了二次场的特性与磁力计信号特性之间的对应关系。特别是，我们表明二次场的两个分量被映射到原子磁力计信号的幅度和相位上。因此，尽管原子磁力计本质上是标量磁场测量，但它能提供关于二次场的半矢量信息。此外，我们展示了一种确定缺陷尺寸的稳健方法，该方法不受传感器尺寸的限制。我们证明，观察到的分布的幅度和相位对比度使我们能够可靠地测量缺陷深度。
