Fluorescence quenching in combined scans of DNA origami. Two examples of DNA origami scans in which quenching of both fluorophores is clearly visible. The comparison of the location of the quenched spots shows that the DNA structure in (a) is upside-down with respect to the one in (b). Thus, using quenching imaging on asymmetric structures, we can determine their orientation on the surface without ambiguity. The intensity scale in all images has been adjusted to give maximum visual contrast and the lowest value (black) is, in general, higher than zero counts.