Low Temperature Scanning NV Centre Microscope

We present the development of a cryogenic scanning probe magnetometer based on a diamond tip hosting a single NV center. Our microscope integrates a 0.82 NA / 1mm WD low-temperature apochromatic objective (540–780 nm) a flexure XYZ Piezo scanner with 30 µm × 30 µm × 15 µm scan range and a piezo-driven XYZ nanopositioning stage for sample. NV Centre probe is attached at the end of a quartz tuning fork and is brought into the focal point of the objective using another XYZ piezo nanopositioner. The optomechanical design incorporates independent laser excitation and white-light imaging channels, enabling high-resolution micro-Raman spectral mapping of specimen and photon counting from individual NV centers to image magnetic domains of surfaces. By resolving continuous-wave optically detected magnetic resonance (CW-ODMR) spectra with high contrast and signal-to-noise ratio, the system demonstrates the sensitivity and stability required for quantitative nanoscale magnetic imaging. The implementation of a low-noise amplifier enables high-fidelity detection of the quartz tuning fork resonance curve, making stable operation in the vicinity of atomic forces feasible. Outer diameter of the microscope is 48mm and is operated in our Ultra Low Vibration Cryostat with 1.3-300K range and 12T magnet. Preliminary scans of hard-disk bit structures confirm the instrument's performance and its readiness for advanced quantum sensing applications.