Triaxial closed-loop measurement based on a single-beam zero-field optically pumped magnetometer

Abstract

In this study, we propose an approach for the simultaneous measurement of triaxial magnetic fields using a single-beam zero-field optically pumped atomic magnetometer, in which a rotational high-frequency (ω1) and another high-frequency (ω2) modulated magnetic field magnetic fields are applied along the transverse directions and the longitudinal direction, respectively. Theoretical analysis, numerical simulation, and experiments are conducted to demonstrate this method. Experimental sensitivities of 18 fT/Hz1/2 along the two transverse directions and 140 fT/Hz1/2 along the longitudinal direction are simultaneously achieved. On this basis, we operate the magnetometer in closed-loop mode to expand the bandwidth and dynamic range, and to keep the triaxial magnetic field sensed by the magnetometer at zero. The triaxial bandwidths are increased from below 100 Hz to over 1.6 kHz. The triaxial dynamic ranges are all extended to ±150 nT. Plus, we verify the ±1,000 nT dynamic range of the triaxial magnetometer through increasing the triaxial coil constants. The synchronization of triaxial closed-loop measurement, simplicity of magnetometer structure, and closed-loop detection with high sensitivities make it applicable and attractive for biomagnetism imaging in challenging environments.

The suppression of the probe laser pumping effect in SERF atomic magnetometer

“…x B z 0 ( )− P e x B z ± B z0 ( ) min (7) where ΔS is the difference between maximum and minimum signals.…”

“…It has been widely studied since it was first proposed [1,2]. There exists considerable potential in basic physical research [3][4][5] and ultra-high sensitive magnetic field detection [6][7][8] related to SERF magnetometers. As a type of multi-system ultra-high sensitivity sensor, the noise level of an information detection system in a SERF atomic magnetometer limits its serviceability [9,10].…”

Feedback Methods for Vector Measurements Using an All-Optical Atomic Magnetometer

“…Improvements in production techniques and quality of components, accompanied by increased portability and sensitivity, has resulted in increased interest in optical atomic magnetometers, often called "optically pumped magnetometers" (OPMs). Recent work has demonstrated their ability to achieve sub-fT/ √ Hz sensitivities in near-zero field environments [15] and 3-axis vector sensitivity in near-zero-field environments [4,5,[16][17][18], µT-level environments with relatively small vector components orthogonal to the bias field [19], and yet more advances have been made in extending the operational range of spin-polarized optically pumped magnetometers into the Earth-field regime [20][21][22][23].…”