Quantum diamond microscope with circularly polarized microwave excitation for wide-field vector magnetometry

We report a quantum diamond microscope for rapid, spatially resolved magnetic imaging across a wide-field of view. We use it to measure optically detected magnetic resonance spectra of randomly oriented single crystal nanodiamonds with dense NV- ensembles, serving as local sensors of magnetic fields. A novel planar microwave resonator, able to produce arbitrary in-plane polarizations is used for polarization-sensitive control of electron spins. The resonator exhibits more than 200 MHz bandwidth, extended homogeneous region, and magnetic field strength surpassing 29 A/m at 1 W input power. Circularly polarized microwaves are used to identify selected spin-transitions in order to retrieve the direction of magnetic field. The presented system holds potential for applications in diverse fields, including material science, biology, and space research.