Reducing crosstalk in optically-pumped magnetometer arrays

Optically pumped magnetometers (OPMs) operating in the spin-exchange relaxation-free regime are emerging as alternative sensors to superconducting quantum interference devices (SQUIDs) for magnetoencephalography (MEG). As the number of OPMs in a single imaging system increases to rival SQUID MEG systems, cross-talk between nearby sensors limits the measurement accuracy. We experimentally demonstrate a coil geometry, which generates an order of magnitude less cross-talk (less than 0.5 %) than a Helmholtz coil (8 %). The new coil design is simple and compact, requiring two coaxial coil pairs that add 1 mm to the 6 mm radius and is driven by a single current driver. The new design also maintains excellent magnetic field homogeneity over the volume of the magnetometer. Our result increases the feasibility of a high signal-to-noise ratio in high-density OPM-based bio-magnetic imaging technology.