Vector measurement of pico tesla magnetic fields using an optically pumped magnetometer by varying pump beam direction

Abstract

Optically pumped magnetometers (OPMs) with ultrahigh sensitivities are expected to be alternative magnetic sensors to superconducting quantum interference devices. Already studies on vector measurements using OPMs have been done, but they have several limitations, which have to be overcome. Herein, we proposed a new method to estimate the magnetic field direction for a pump-probe type OPM. The method measures the magnetic field by varying a pump beam direction in a plane perpendicular to the probe beam and then estimates the direction of the measurement field from the change in the magnitude of the acquired signal. The proposed principle was validated using numerical simulations assuming various conditions encountered in practical measurements. The simulation results indicated that our method can achieve an estimation accuracy of 0.1°, which satisfies the accuracy required in practical applications.