Figure 2

Wide-field imaging of the iso-magnetic field contours of an array of magnetically encoded bits.

(a) Iso-magnetic field image showing in white the contours of the stray field projection B_{NV, i = 1.4} =  ± 2.9 mT (probe MW frequency 2.79 GHz). The image is formed by dividing two fluorescence images with and without MW excitation. The imaging area is 100 × 100 μm² and the integration time is 48 s. (b) Iso-magnetic field image showing in white the contours of the projection B_{NV,i = 1.4} = 0 mT (probe MW frequency 2.87 GHz) with an integration time of 48 s. (c) Line cut from a single iso-magnetic field line in (b), demonstrating a magnetic imaging resolution of 440 nm. (d–f) Iso-magnetic field images of a separate area of the drive with the white contours representing the projection B_{NV,i = 1.4} = 0 mT (probe MW frequency 2.87 GHz) at varying exposure times from 48 s down to 20 ms.