Fig. 1

Preparation of NDs and schematic of the wide-field ODMR set-up. a NDs, 156 nm and 48 nm in size were obtained by milling bulk, ¹³C-enriched HPHT fluorescent diamond. b Schematics of the inverted wide-field ODMR microscope. Green laser light is focused onto the sample. The fluorescence is collected by the objective through a dichroic mirror to the high-sensitivity CMOS camera. The image shows an actual fluorescence image of NDs deposited on a glass slide. MW delivery is obtained with a loop adjacent to the sample. The panel shows the temporal diagram of the CW-ODMR experiment. The laser is kept ON during the entire measurement, while the camera detects the fluorescence image synchronously with the MW irradiation. c Photo of the wide-field ODMR microscope set-up