  We report the modification of a label-free image scanning microscope (ISM) to
perform asynchronous 2D imaging at 24kHz while keeping the lateral resolution
gain and background rejection of a regular label-free ISM setup. Our method
uses a resonant mirror oscillating at 12kHz for one-direction scanning and a
chromatic line for instantaneous scanning in the other direction. We adapt
optical photon reassignment in this scanning regime to perform fully optical
super-resolution imaging. We exploit the kHz imaging capabilities of this
confocal imaging system for single nanoparticle tracking down to 20nm for gold
and 50nm for silica particles as well as imaging freely moving Lactobacillus
with improved resolution.
