Measuring Field Strength with an Optically Pumped Magnetometer

<div><div>This animation demonstrates the principles behind a new device for measuring the strength of magnetic fields. One potential application for the technology is mapping electrical activity in the brain, for use in diagnosing traumatic brain injuries. Unlike typical instruments used today, the new magnetometer prototypes do not require cooling and can be placed within a few millimeters of the scalp.&nbsp;<br></div><div><br></div><div>The prototype consists of a glass cell filled with a cloud of rubidium atoms. First, polarized laser light aligns the rubidium atoms’ spins. Then, an applied magnetic field deflects the atomic spins around the axis of the field, which decreases the amount of laser light that is transmitted through the cloud of atoms. Monitoring the amount of transmitted light provides a measure of the strength of the magnetic field. Animation: Sean Kelley/NIST</div></div>