We show that the position of a fluorescent nanoparticle can be measured in three dimensions with subnanometer precision and 100-ms temporal resolution by use of standard epifluorescence video imaging in off-focus mode. The particle can be tracked without feedback in a volume of at least 40μmχ60χm χ3m . With the technique presented, the structure–mobility relationship of 216-nm latex particle in a porous polymer network was studied in three dimensions.
© 2003 Optical Society of America
Michael Speidel, Alexandr Jonáš, and Ernst-Ludwig Florin, "Three-dimensional tracking of fluorescent nanoparticles with subnanometer precision by use of off-focus imaging," Opt. Lett. 28, 69-71 (2003)