Mapping the Cardiomagnetic Field with 19 Room Temperature Second-Order Gradiometers

Abstract

We present a laser pumped 19 channel second-order magnetometer system for measuring magnetic fields produced by the beating human heart. Each field sensor is a room-temperature paraffin-coated cesium vapor cell operated in a standard M _x magnetometer configuration based on optically detected magnetic resonance with circularly polarized D1 pumping on the F = 4 →F′ = 3 component of the D₁ transition. Dynamic magnetic field maps are derived from the simultaneous recording at 19 grid points. The system has been successfully used for recording (in less than 2 minutes) cardiac field maps of more than 30 healthy subjects. We also report a recording of the MCG of a patient with a nonspecific intraventricular conduction defect, which represents the first detection of a cardiac anomaly by an atomic magnetometer array.