Dependence on sensitivity patterns of bias fields for vector measurements using optically pumped vapor magnetometers

Janet W Lou,Geoffrey A Cranch

doi:10.1063/5.0024273

Abstract

The optical light shift effect is an all-optical technique to create magnetic bias fields to determine the vector components of the magnetic field using a scalar optically pumped magnetometer. We show that the measurement of the induced bias fields is affected by the response pattern of the scalar magnetometer. The sensitivity of the magnetometer affects the minimum total field resolution as well as the angular resolution of the vector measurement. Three configurations of multiple-laser, optically pumped cesium vapor vector magnetometers are characterized for their spatial sensitivity patterns. Each configuration has a unique response level as a function of the relative magnetic field orientation. Thus, the formulations used for angular determination are dependent on the magnetometer configuration, and the angular resolution of the vector measurement is dependent on the relative angle between the magnetic field and the optical probe beam. The spatial dependence of the light shift signals is measured, and the equations describing their responses are presented for each configuration. Equations for determining the field angles from the bias field responses are derived.

Highlights

Atomic vapor magnetometers based on the measurement of the Larmor precession frequency yield the scalar magnitude of the total magnetic field
By using calibrated coils along three orthogonal axes to cancel the field, the existing magnetic field is of the same amplitude but opposite in direction to the field generated by the coils
We report the experimentally measured effect of the spatial sensitivity on the light shift (LS) bias field measurements and determine the mathematical equations to describe the geometric and spatial dependence of the LS generated signals for each of three multiple-laser magnetometer configurations

Summary

Introduction

Atomic vapor magnetometers based on the measurement of the Larmor precession frequency yield the scalar magnitude of the total magnetic field. Several approaches to determine the vector field components have been proposed. Atomic vapor magnetometers based on the measurement of the Larmor precession frequency yield the scalar magnitude of the total magnetic field.. Several approaches to determine the vector field components have been proposed. By using calibrated coils along three orthogonal axes to cancel the field, the existing magnetic field is of the same amplitude but opposite in direction to the field generated by the coils.. The spatial dependence of magnetometer response can be used to determine the field direction by comparing the results of multiple measurements, for example, at different harmonics of the Larmor frequency.. The need to make multiple sequential measurements increases the system complexity and may not be well-suited for detecting transient magnetic signals. Bias fields can be arranged to provide information about all three field components simultaneously

Methods

Discussion

Conclusion