# Performance analysis of an optically pumped magnetometer in Earth's magnetic field

## TL;DR

This paper experimentally analyzes how the orientation of optically pumped magnetometers affects their performance in Earth's magnetic field, focusing on a mode promising femtotesla resolution and demonstrating robustness against heading errors.

## Contribution

It provides an experimental evaluation of the LSD-Mz regime's key parameters and shows that using balanced laser beams reduces heading errors and maintains sensitivity across orientations.

## Key findings

- Heading error is minimal with balanced laser beams.
- Field sensitivity remains stable over a wide orientation range.
- The regime achieves femtotesla-level resolution in Earth's magnetic field.

## Abstract

We experimentally investigate the influence of the orientation of optically pumped magnetometers in Earth's magnetic field. We focus our analysis to an operational mode that promises femtotesla field resolu-tions at such field strengths. For this so-called light-shift dispersed Mz(LSD-Mz) regime, we focus on the key parameters defining its performance. That are the reconstructed Larmor frequency, the transfer function between output signal and magnetic field amplitude as well as the shot noise limited field resolution. We demonstrate that due to the use of two well balanced laser beams for optical pumping with different helicities the heading error as well as the field sensitivity of a detector both are only weakly influenced by the heading in a large orientation angle range.