title: Note: Three-dimensional linearization of optical trap position detection for precise high speed diffusion measurements.
abstract: Studies of the details of Brownian motion, hydrodynamic of colloids, or protein diffusion measurements all require high temporal and spatial resolution of the position detector and a means to trap the colloid. Optical trap based thermal noise imaging employing a quadrant photodiode as detector provides such a method. However, optical trapping requires an objective with high numerical aperture resulting in highly nonlinear position signal and significant cross-dependence of the three spatial directions. Local diffusion measurements are especially susceptible to distance errors. Here, we present a position calibration method, which corrects nonlinearities sufficiently to allow precise local diffusion measurement throughout the entire trapping volume. This correction permits us to obtain high-resolution two- and three-dimensional diffusion maps.
authors.affiliation: Department of Physics, State University of New York at Buffalo, 239 Fronczak Hall, Buffalo, New York 14260-1500, USA.
authors.forename: Y-H
authors.initials: YH
authors.lastname: Hsu
authors.affiliation: Department of Physics, State University of New York at Buffalo, 239 Fronczak Hall, Buffalo, New York 14260-1500, USA.
authors.forename: A
authors.initials: A
authors.lastname: Pralle
mesh_terms: D002138:Calibration; D004058:Diffusion; D017711:Nonlinear Dynamics; D052898:Optical Tweezers
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