# Detection of low-conductivity objects using eddy current measurements with an optical magnetometer

## TL;DR

This paper demonstrates that an optical magnetometer can detect low-conductivity objects via eddy current measurements, significantly improving sensitivity and opening possibilities for non-invasive medical diagnostics.

## Contribution

The study introduces a noise-canceling optical magnetometer capable of detecting low-conductivity objects with high sensitivity, surpassing previous methods.

## Key findings

- Detected small salt-water containers with conductivity 4-24 S/m
- Achieved over three orders of magnitude increase in SNR
- Potential to detect objects with conductivity below 1 S/m

## Abstract

Detection and imaging of an electrically conductive object at a distance can be achieved by inducing eddy currents in it and measuring the associated magnetic field. We have detected low-conductivity objects with an optical magnetometer based on room-temperature cesium atomic vapor and a noise-canceling differential technique which increased the signal-to-noise ratio (SNR) by more than three orders of magnitude. We detected small containers with a few mL of salt-water with conductivity ranging from 4-24 S/m with a good SNR. This demonstrates that our optical magnetometer should be capable of detecting objects with conductivity < 1 S/m with a SNR > 1 and opens up new avenues for using optical magnetometers to image low-conductivity biological tissue including the human heart which would enable non-invasive diagnostics of heart diseases.