Wesseler J, Nagy R (2026)
Publication Status: In review
Publication Type: Unpublished / Preprint
Future Publication Type: Journal article
Publication year: 2026
DOI: 10.48550/arXiv.2606.18871
Transitioning quantum magnetometry from laboratory environments to real-world applications has been limited by a persistent trade-off between sensor miniaturization and magnetic sensitivity. While bulky systems can achieve high sensitivity, endoscopic probes commonly suffer from inefficient fluorescence collection and reduced performance. Here we resolve this trade-off and present a miniaturized diamond quantum magnetometer with a 6 mm diameter endoscopic sensor head, achieving a magnetic-field sensitivity of 91 pT/sqrt(Hz) with a 2 kHz measurement bandwidth in a magnetically unshielded environment. The fluorescence collection bottleneck is overcome by separating excitation and collection into different cores of a fused multi-core fiber bundle, coupled to the diamond through a custom high-numerical-aperture micro-objective. A compact FPGA-based backend performs microwave control, lock-in detection and real-time resonance tracking, enabling robust operation during magnetic-field imaging. To demonstrate the practical utility of the miniaturized sensor, we image the magnetic field of a commercial lithium-ion pouch cell during charge and discharge and reconstruct depth-integrated current-density maps of the current flow. These results show that endoscopic diamond magnetometers can combine high sensitivity with a probe geometry suitable for confined, unshielded measurements, opening new avenues in battery technology and beyond.
APA:
Wesseler, J., & Nagy, R. (2026). Sensitive endoscopic diamond magnetometer for non-contact sensing in confined environments. (Unpublished, In review).
MLA:
Wesseler, Johannes, and Roland Nagy. Sensitive endoscopic diamond magnetometer for non-contact sensing in confined environments. Unpublished, In review. 2026.
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