Through-skin pilot-hole detection and localization with a mechanically translatable atomic magnetometer

Abstract

We demonstrate through-skin electromagnetic induction imaging of pilot-holes in an aluminum block concealed by a 0.41 mm thick aluminum shield with a 1.49 kg mechanically translatable radio frequency atomic magnetometer. The pilot-holes are identified and localized with submillimeter accuracy both with and without the Al shield. We utilize a dual-frequency technique to isolate the image of the target while removing the effect of the shielding from the image. Imaging accuracy is shown to be robust in a range of different operating conditions and immune to the effect of a thermal insulator between the shielding and the target. The approach introduced here finds direct application in aircraft wing manufacture and is competitive with existing approaches.

Imaging corrosion under insulation with a mechanically-translatable atomic magnetometer

“…We use a simple peak detection algorithm in MATLAB to define the peak and trough. We then define the recess centre as the midpoint between the peak and trough of the dispersive shape in ϕ, as in our previous work on pilot-hole detection [16].…”

“…The imaging system consists of a compact radio-frequency atomic magnetometer (RF-AM) [11], [12] operating in electromagnetic induction imaging modality [13], [14]. The system was described in detail previously [15], [16], and we recall here only the essential details.…”

How to build a magnetometer with thermal atomic vapors: A tutorial

“…Biomedical magnetomyography (MMG) [145,161], magnetoencephalography (MEG) [83,121,122,128,134,[162][163][164][165][166], (fetal) magnetocardiography (MCG and fMCG) [19,20,92,120,164,167], magnetic-field imaging (MFI) [168] magnetic biomarkers [124,[169][170][171][172] plant biomagnetism [173,174] Zero-/low-field NMR [125,126,139,[175][176][177][178][179]] Geophysics [85,180] Aerospace [102,181] Laser guide stars [182] Defense and industry underwater surveillance [135], electromagnetic induction imaging [183][184][185][186] Fundamental science search for new physics beyond particle standard model [38,76,…”

Two-photon electromagnetic induction imaging with an atomic magnetometer

“…The resonance is swept with the RF fields and a linewidth (HWHM) of the resonance C ¼ 2p  680 Hz is typical for the system. The portable RF-AM is raster-scanned across an object using a 2D mechanical translational stage and builds up a conductivity image of static targets, which has been able to detect features masked by conductive shields 16 and simulated corrosion under insulation. 17 For the two-photon scheme, two identical RF coils (6 mm diameter and 10 mm length) are driven by waveform generators, at their respective frequencies of x RF and x c .…”