Vector Measurements Using All Optical Scalar Atomic Magnetometers

TL;DR

This paper demonstrates a novel all-optical scalar atomic magnetometer capable of measuring vector magnetic fields by extracting polar and azimuthal angles with high precision using intrinsic scalar parameters.

Contribution

It introduces a method to obtain vector field information from a scalar atomic magnetometer by analyzing the probe signals and light-shift effects, enabling vector measurements with high accuracy.

Findings

Achieved better than 0.02 degree sensitivity in polar angle measurement.

Recorded less than 1 degree error over most polar angles.

Demonstrated azimuthal angle measurement with orthogonal sensors.

Abstract

Vector field measurement is demonstrated with an all-optical scalar atomic magnetometer using intrinsic parameters related to its scalar operation. The Bell-Bloom type atomic magnetometer measures the Larmor precession of cesium atoms through on-resonant absorption of a probe beam. While the AC component of the probe signal is used for the field magnitude measurement, the probe DC signal contains information about the polar angle, defined as the angle between the magnetic field and the probe beam. Additional polar angle information is obtained from the light-shift-induced magnetic field caused by the frequency modulation of the probe beam. With a measurement time of 100 milliseconds, better than 0.02 degree sensitivity has been achieved using a commercial miniaturized sensor at the optimal sensor orientation. The angle measurement accuracy is checked against an optical encoder over the entire polar angle range of 0 to 180 degrees. Better than 1 degree error is recorded over most set polar angles. Azimuthal angle measurement is also exhibited with two orthogonally oriented sensors.