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Fig. 1 | Nanoscale Research Letters

Fig. 1

From: Ground-State Depletion Nanoscopy of Nitrogen-Vacancy Centres in Nanodiamonds

Fig. 1

a Principle of the GSD in \({\text{NV}}^{ - }\) in NDs using a probe beam at 594 nm (yellow), a depletion beam at 638 nm (red) and a reset beam at 488 nm (blue). GS ground state, ES excited state and MS metastable state of the NV centre. Illustration of an NV centre in a nanodiamond. b Schematic representation of the experimental set-up. The system consists of a home-built confocal microscope with three lasers operating at the wavelengths of 488 nm, 594 nm and 638 nm. A vortex phase plate spatially engineers the 638 nm depletion beam into a donut beam to ensure depletion only around the diffraction limited area. c Characterisation of acousto-optic modulators by measuring the pulse arrival times of each laser. d Schematic of the pulse sequence used in GSD nanoscopy. The detection window is synchronised to the probe beam at 594 nm to collect only relevant fluorescence. The pulse length of the 594 nm probe beam was optimised at 20 μs, as a shorter pulse length would result in longer averaging times and longer pulse lengths would lead to less efficient super-resolution imaging. The 488 nm reset beam was optimised at 20 μs as it is preferable to have it as short as possible to reduce the overall pulse sequence time but still empty the long-lived metastable state effectively

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