Investigations of optical aberration on quantum diamond microscopy toward high spatial resolution and sensitivity.

This article focuses on quantitatively analyzing the impact of optical aberrations caused by diamond thickness on the resolution of quantum diamond microscopy (QDM), which uses nitrogen-vacancy (NV) center ensembles to image magnetic fields with high spatial resolution. Employing a rigorous diffraction integral model that incorporates aberrations, the study experimentally verifies the point spread function (PSF) of single NV centers at various depths using confocal microscopy and extends the analysis to wide-field microscopy. Results indicate that to achieve the diffraction-limited resolution (~500–600 nm) in typical QDM optical systems (numerical aperture NA ≈ 0.7), the diamond thickness must be less than about 40 μm, while a thickness below 100 μm allows for a 1 μm resolution across a wide field of view (~100 μm). Commercially available diamonds of 500 μm thickness yield degraded resolution (~1.5 μm at the center and ~3 μm at the edges), highlighting the practical importance of diamond thinning for enhanced QDM performance.