Pulsed Vector Magnetometry for active brain scans

Optically pumped magnetometers (OPMs) have recently shown promise for providing an alternative to superconducting quantum interference devices (SQUIDs) in performing magnetoencephalography (MEG). Unlike SQUIDs however, OPMs do not need to operate at cryogenic temperatures reducing their required standoff distance from a human subject and allowing for a patient to move around a room during a scan. However, many commercially available OPM systems fail to approach the theoretical limits of a spin exchange relaxation free magnetometer only hitting ~ 14.9 ft/rt-Hz. One of the reasons for this shortcoming is the presence of laser noise during measurements. Our group plans to implement a novel vector OPM scheme capable of achieving ~2 ft/rt-Hz, by incorporating magnetic field and light pulses. This scheme reduces the contributions from pump noise as the pump is only on for a small amount of time, lowering the theoretical noise floor of our sensor. The application of field pulses also allow us to collect information about multiple axes simultaneously along the same beam path,  many commercial systems that must take information about each field component separately, or separate the location where information about one or more component is gatherer.