Figure 2. Thermal noise imaging of a thick and optically dense filament.

(a) Since thick filaments cannot be imaged by individual trapping volumes, the center position of the optical trap is instead moved on a grid and individual thermal noise images at each grid position are acquired and subsequently combined to yield a single large image. (b) Combined thermal noise image of a collagen fibril that has not yet been corrected for light scattered by the optically dense filament. (c) Same data as b, but corrected for light scattered by the imaged fibril (see Methods). Isosurfaces are shown at 10 counts. Scale bars, 200 nm.