Quantum Diamond Microscope for Narrowband Magnetic Imaging with High Spatial and Spectral Resolution

TL;DR

This paper presents a quantum diamond microscope integrated with a narrowband measurement protocol and lock-in camera, enabling high-resolution, tunable RF magnetic field imaging with spectral resolution around 1 Hz and applications in various fields.

Contribution

The work introduces a novel RF quantum diamond microscope that achieves simultaneous high-resolution spatial and spectral imaging of narrowband magnetic fields with tunable frequency detection.

Findings

Spatial resolution of approximately 2 micrometers.

Spectral resolution of about 1 Hz.

Sensitivity to narrowband fields around 1 nT·Hz^{-1/2}.

Abstract

The quantum diamond microscope (QDM) is a recently developed technology for near-field imaging of magnetic fields with micron-scale spatial resolution. In the present work, we integrate a QDM with a narrowband measurement protocol and a lock-in camera; and demonstrate imaging of radiofrequency (RF) magnetic field patterns produced by microcoils, with spectral resolution $\approx1$\,Hz. This RF-QDM provides multi-frequency imaging with a central detection frequency that is easily tunable over the MHz-scale, allowing spatial discrimination of both crowded spectral peaks and spectrally well-separated signals. The present instrument has spatial resolution $\approx2\,\mathrm{\mu m}$, field-of-view $\approx300\times300\,\mathrm{\mu m^2}$, and per-pixel sensitivity to narrowband fields $\sim{1}\,$nT$\cdot$Hz$^{-1/2}$. Spatial noise can be reduced to the picotesla scale by signal averaging and/or spatial binning. The RF-QDM enables simultaneous imaging of the amplitude, frequency, and phase of narrowband magnetic field patterns at the micron-scale, with potential applications in real-space NMR imaging, AC susceptibility mapping, impedance tomography, analysis of electronic circuits, and spatial eddy-current-based inspection.