ISM-FLUX: MINFLUX with an array detector

Abstract

Single-molecule localization based on the concept of MINFLUX allows for molecular resolution imaging and tracking. However, MINFLUX has a limited field-of-view (FOV) and therefore requires a precise pre-localization step. We propose ISM-FLUX, a localization technique that combines structured illumination with structured detection. We show via simulations that by replacing the point-detector with a small single-photon detector array (e.g., of 5 x 5 elements) and sequentially exciting the sample with four spatially separated doughnut-shaped beams, a localization uncertainty between 1 and 15 nm can be obtained over a FOV of more than 800 nm with 100 photons. The large FOV and the extra spatial information induced by the detector array relax the requirements on prior information on the fluorophores position. In addition, ISM-FLUX allows the localization of multiple molecules simultaneously. We calculate the effect of different parameters, such as the relative position of the doughnut beams, the number of detector pixels, the number of photons and the signal-to-background ratio, on the localization uncertainty. We predict that the combination of a good localization precision and the experimental simplicity of ISM-FLUX will help the wide adoption of MINFLUX and other derived microscopy techniques.