Optically Pumped Magnetometers Recent Advances and Applications in Biomagnetism: A Review

Alkali metal optically pumped magnetometers (OPMs), with a particular emphasis on spin-exchange relaxation-free (SERF) atomic magnetometers, have garnered considerable attention due to their remarkable sensitivity. In this comprehensive review, we present a succinct overview of the fundamental principle of the magnetometer and the various categories of its central sensitive unit, namely the cell. We then proceed to elaborate on the vital aspect of establishing an extremely feeble magnetic field environment that is crucial for its operation, inclusive of both active magnetic shielding and passive magnetic compensation methodologies. In furtherance, we conduct a thorough evaluation of the pros and cons of single-beam and dual-beam pump-probe scheme magnetometers, followed by a detailed investigation of their potential applications in the cardiology and brain magnetism fields. Finally, we conclude with an analysis of the hurdles and prospective development directions for alkali metal-based atomic magnetometers in the domains of magnetocardiography (MCG) and magnetoencephalography (MEG), which hold the promise of substantial progress and widespread adoption in the biomedical area.