Real space magnetic resonance microscopy with quantum sensors: widefield and scanning approaches

Microscopy is a cornerstone of scientific instrumentation, which has enabled a deep understanding of structures and processes at the smallest scales. Cameras have advanced optical, infrared, and electron microscopy, providing simultaneous measurements over a wide field of view without the need for scanning techniques. Imaging nuclear magnetic resonance (NMR) signals with their host of valuable information, however, has remained elusive. Here, we present techniques for NMR microscopy capable of recording full (NMR) spectra across a quantum sensor in parallel. We use nitrogen-vacancy centers in diamond capable of transcoding local signals into optical ones to be recorded using a light microscope. In contrast to traditional methods, we neither rely on magnetic field gradients to encode location nor on standard scanning approaches prone to parameter drifts. Instead, our technique allows for simultaneous signal encoding across the sensor. We demonstrate our novel microscopy techniques by imaging the water NMR signal emitted from the channel structure of a sample-carrying microfluidic chip with a spatial resolution of ~10 μm. The first technique, Optical Nuclear Magnetic Resonance Microscopy (OMRM), utilizes a camera to transcode and image the signal simultaneously across the entire field of view, enabling parallel acquisition. The second technique, Time-to-Space (T2S), performs the signal transcoding over the entire diamond sensor at once and uses a photodiode and acousto-optic modulator to scan only the readout location. This approach converts the sequential measurement process into a spatial scan across the sensor, allowing for straightforward integration into existing experimental setups. These techniques pave the way for advanced NMR microscopy with applications in biological imaging to characterizing thin film materials.