A Compact, Portable Device for Microscopic Magnetic Imaging Based on Diamond Quantum Sensors

Magnetic imaging based on ensembles of diamond nitrogen-vacancy quantum sensors has emerged as a useful technique for the spatial characterization of magnetic materials and current distributions. However, demonstrations have so far been restricted to laboratory-based experiments using relatively bulky apparatus and requiring manual handling of the diamond sensing element, hampering broader adoption of the technique. Here a simple, compact device that can be deployed outside a laboratory environment and enables robust, simplified operation is presented. It relies on a specially designed sensor head that directly integrates the diamond sensor while incorporating a microwave antenna and all necessary optical components. This integrated sensor head is complemented by a small control unit and a laptop computer that displays the resulting magnetic image. The device is tested by imaging a magnetic sample, demonstrating a spatial resolution of 4 µm over a field of view exceeding 1 mm, and a best sensitivity of 45 µT $$ per (5 µm)² pixel. The portable magnetic imaging instrument may find use in situations where taking the sample to be measured to a specialist lab is impractical or undesirable.