Development of Optically Pumped Magnetometers towards Next Generation Biomagnetic Neuroimaging

Optically pumped magnetometers (OPMs) using alkali-metal atoms are capable of measuring extremely small magnetic fields. After describing principles of the pump-prove-type OPM, we introduce our newly developed compact OPM module having its noise floor was less than 20 fT
rms
/Hz
^1/2
as well as results of magnetoencephalography (MEG) measurements. In addition, we introduce the first magnetic shieldless ultra-low-field MRI scanner with an OPM operating at a Larmor frequency of 300 kHz. The applicability of the OPM-based MEG-MRI fused system might provide important advancements of biomagnetic neuroimaging.