School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
Rev Sci Instrum. 2022 Dec 1;93(12):125103. doi: 10.1063/5.0102402.
Electrically conductive objects can be detected using the principle of electromagnetic induction, where a primary oscillating magnetic field induces eddy currents in the object, which in turn produce a secondary magnetic field that can be measured with a magnetometer. We have developed a portable radio-frequency optically pumped magnetometer (RF OPM) working in unshielded conditions with sub-pT/Hz magnetic field sensitivity when used for the detection of small oscillating magnetic fields, setting a new benchmark for the sensitivity of a portable RF OPM in unshielded conditions. Using this OPM, we have detected the induced magnetic field from aluminum disks with diameters as small as 1.5 cm and with the disks being ∼25 cm from both the excitation coil and the magnetometer. When used for eddy current detection, our magnetometer achieves a sensitivity of a 2-6 pT/Hz. We have also detected a moving aluminum disk using our RF OPM and analyzed the magnetometer signals, which depend on the position of the disk, illustrating the potential of high sensitivity RF OPMs for remote sensing applications.
我们已经开发出一种便携式射频光泵磁力计(RF OPM),可在非屏蔽条件下工作,当用于检测小的振荡磁场时,磁场灵敏度可达亚皮特斯拉每赫兹,创下了非屏蔽条件下便携式 RF OPM 灵敏度的新基准。使用这种 OPM,我们已经检测到直径小至 1.5 厘米的铝盘产生的感应磁场,并且这些磁盘与激励线圈和磁力计之间的距离均约为 25 厘米。当用于涡流检测时,我们的磁力计实现了 2-6 皮特斯拉每赫兹的灵敏度。我们还使用 RF OPM 检测了一个移动的铝盘,并对磁力计信号进行了分析,该信号取决于磁盘的位置,这说明了高灵敏度 RF OPM 用于远程感应应用的潜力。
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