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arXiv · 2008.01570

Integrated optically pumped magnetometer for measurements within Earth's magnetic field

G. Oelsner·R. IJsselsteijn·T. Scholtes·A. Krüger·V. Schultze·G. Seyffert·G. Werner·M. Jäger·A. Chwala·R. Stolz
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Abstract

We present a portable optically pumped magnetometer instrument for ultra-sensitive measurements within the Earth's magnetic field. The central part of the system is a sensor head operating a MEMS-based Cs vapor cell in the light-shift dispersed Mz mode. It is connected to a compact, battery-driven electronics module by a flexible cable. We briefly review the working principles of the device and detail on the realization of both, sensor head and electronics. We show shielded and unshielded measurements within a static magnetic field amplitude of 50 uT demonstrating a noise level of the sensor system down to 140 fT/\sqrt{Hz} and a sensor bandwidth of several 100 Hz. In a detailed analysis of sensor noise we reveal the system to be limited by technical sources with straightforward strategies for further improvement towards its fundamental noise limit of 12 fT/\sqrt{Hz}. We assess the parameters defining the sensor bandwidth by theoretical modeling based on the Bloch equations. Finally, we compare our sensors' performance to a commercial SQUID system in a measurement environment typical for geomagnetic observatory practice and geomagnetic prospection.

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G. Oelsner, R. IJsselsteijn, T. Scholtes, A. Krüger, V. Schultze, G. Seyffert, G. Werner, M. Jäger, A. Chwala, R. Stolz. 2021-10-01. Integrated optically pumped magnetometer for measurements within Earth's magnetic field. https://doi.org/10.1103/physrevapplied.17.024034

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