Optically-Pumped Magnetometers for MEG

Optically-pumped magnetometers (OPMs) have seen rapid progress over the last decade in terms of performance and technology development. As highly sensitive room-temperature magnetometers they present several advantages over superconducting quantum interference device (SQUID) sensors, such as the possibility for conformal geometries and low-maintenance systems. We review the state of the art and different types of low-field OPMs, as well as the first magnetoencephalography (MEG) demonstrations with OPMs. Several challenges remain, such as the demonstration of OPM multichannel systems, their limited dynamic range, and the demonstration of gradiometric operation to name just a few. Certainly OPMs present a promising technology to complement existing SQUID-based installations.