Determination and correction of position detection nonlinearity in single particle tracking and three-dimensional scanning probe microscopy.
A general method is presented for determining and correcting nonlinear position detector responses in single particle tracking as used in three-dimensional scanning probe microscopy based on optical tweezers. The method uses locally calculated mean square displacements of a Brownian particle to detect spatial changes in the sensitivity of the detector. The method is applied to an optical tweezers setup, where the position fluctuations of a microsphere within the optical trap are measured by an interferometric detection scheme with nanometer precision and microsecond temporal resolution. Detector sensitivity profiles were measured at arbitrary positions in solution with a resolution of approximately 6 nm and 20 nm in the lateral and axial directions, respectively. Local detector sensitivities are used to reconstruct the real positions of the particle from the measured position signals.
Cell Biology and Biophysics Programme, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Christian
C
Tischer
Arnd
A
Pralle
Ernst-Ludwig
EL
Florin