Dual-view microscopy of single-molecule dipole orientations.

Measuring dipole orientations of fluorescent probes offers unique local structural insights of labelled biomolecules and has seen expanding applications in structural biology studies. Here we propose an alternative imaging geometry, 'dual-view' microscopy, for single-molecule dipole orientation measurements. We develop a protocol capable of measuring absorption and emission dipole orientations of single emitters. Further, through simulation, we demonstrate that absorption dipole orientation can be accurately measured with high and uniform precision in three dimensions, significantly outperforming epifluorescence microscopy. Meanwhile the emission dipole is independently narrowed down to four possible orientations and can be uniquely determined with the co-estimated absorption dipole. Dual-view microscopy represents a new paradigm in single-molecule orientation sensing and could have unique applications in imaging under cryogenic temperatures.