Three-dimensional particle tracking via bifocal imaging

Erdal Toprak, Hamza Balci, Benjamin H. Blehm, Paul R. Selvin

Research output: Contribution to journalArticle

161 Scopus citations


We introduce a bifocal imaging method that enables three-dimensional (3D) tracking of both fluorescent and nonfluorescent particles. We accomplish this by simultaneously imaging a focused plane, for in-plane position (x,y), and a defocused plane, for out-of-plane position (z), of a molecule using a single CCD camera. We applied our method to several systems including in vivo melanosome tracking and phagocytosed fluorescent bead tracking. We have achieved 2-5 nm accuracy with a 2-50 ms time resolution.

Original languageEnglish (US)
Pages (from-to)2043-2045
Number of pages3
JournalNano Letters
Issue number7
Publication statusPublished - Jul 2007


ASJC Scopus subject areas

  • Materials Science(all)
  • Electronic, Optical and Magnetic Materials
  • Chemistry (miscellaneous)

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