Measuring the accuracy of particle position and force in optical tweezers using high-speed video microscopy

Graham M. Gibson, Jonathan Leach, Stephen Keen, Amanda J. Wright, Miles J. Padgett

Research output: Contribution to journalArticlepeer-review

167 Citations (Scopus)


We assess the performance of a CMOS camera for the measurement of particle position within optical tweezers and the associated autocorrelation function and power spectrum. Measurement of the displacement of the particle from the trap center can also be related to the applied force. By considering the Allan variance of these measurements, we show that such cameras are capable of reaching the thermal limits of nanometer and femtonewton accuracies, and hence are suitable for many of the applications that traditionally use quadrant photodiodes. As an example of a multi-particle measurement we show the hydrodynamic coupling between two particles. (C) 2008 Optical Society of America.

Original languageEnglish
Pages (from-to)14561-14570
Number of pages10
JournalOptics Express
Issue number19
Publication statusPublished - 15 Sep 2008

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