Active underwater detection with an array of atomic magnetometers

Abstract

We report on a 2×2 array of radio-frequency atomic magnetometers in a magnetic induction tomography configuration. Active detection, localization, and real-time tracking of conductive, nonmagnetic targets are demonstrated in air and saline water. Penetration in different media and detection are achieved thanks to the sensitivity and tunability of the sensors, and to the active nature of magnetic induction probing. We obtained a 100% success rate for automatic detection and a 93% success rate for automatic localization in air and water, up to 190 mm away from the sensor plane (100 mm underwater). We anticipate magnetic induction tomography with arrays of atomic magnetometers finding applications in civil engineering and maintenance, the oil and gas industry, geological surveys, marine science, archeology, search and rescue, and security and surveillance.

Electromagnetic induction imaging with atomic magnetometers: Unlocking the low-conductivity regime

“…Here, variations of conductivity between 10 2 and 10 are expected, on a scale of several millimeters. 1,2 In light of the results presented in this letter, this performance appears achievable in the very short term. Dedicated optimization and validation for specific conditions would then be necessary.…”

“…Contactless and noninvasive access to such information would provide insight and diagnostic tools for several conditions, whose clinical phenotype features modifications of the conductivity of the involved tissues. Examples include degenerative neurological and muscular diseases, fibrosis, skin healing, liver, lung, and mammary gland tumors, 1 hemorrhages, edemas, and cardiac fibrillations. Conditions such as atrial fibrillation have enormous human and economic costs due to nonideal diagnostics and limited access to the fundamental pathogenic mechanisms.…”

“…This is another essential requirement for biomedical imaging and navigation: for example, cancerous tissues can exhibit increases in conductivity up to 500 times. 1 To demonstrate the large dynamic range and the conductivity sensitivity of our system, a simultaneous image at 2 MHz of the six samples of different conductivities is shown in Fig. 2(g).…”

Electromagnetic Induction Imaging with Atomic Magnetometers: Progress and Perspectives

“…In 2018, a proof-of-concept of active underwater detection and tracking was reported with an array of four RF-AMs operating in EMI modality [34]. This demonstrated a detection principle different from the conventional measurement of residual spontaneous magnetisation of the object of interest, and finds direct application in underwater surveillance.…”

Inductive Imaging of the Concealed Defects with Radio-Frequency Atomic Magnetometers

“…In particular, it enables operation at low frequencies, where the change in the penetration depth of the rf field is most significant. This category of sensors includes giant magnetoresistance (GMR) magnetometers [12][13][14], superconducting quantum interference devices (SQUIDs) [15,16] and atomic magnetometers [17][18][19][20][21][22][23][24][25][26].…”