Pixel hopping enables fast STED nanoscopy at low light dose.

The achievable image quality in fluorescence microscopy and nanoscopy is usually limited by photobleaching. Reducing the light dose imposed on the sample is thus a challenge for all these imaging techniques. Various approaches like CLEM, RESCue, MINFIELD, DyMIN and smart RESOLFT have been presented in the last years and have proven to significantly reduce the required light dose in diffraction-limited as well as super-resolution imaging, thus resulting in less photobleaching and phototoxicity. None of these methods has so far been able to transfer the light dose reduction into a faster recording at pixel dwell times of a few ten microseconds. By implementing a scan system with low latency and large field of view we could directly convert the light dose reduction of RESCue into a shorter acquisition time for STED nanoscopy. In this way, FastRESCue speeds up the acquisition locally up to 10-fold and allows overall for a 5 times faster acquisition at only 20% of the light dose in biological samples.