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The Strathprints institutional repository is a digital archive of University of Strathclyde research outputs. Strathprints provides access to thousands of Open Access research papers by University of Strathclyde researchers, including those from the School of Psychological Sciences & Health - but also papers by researchers based within the Faculties of Science, Engineering, Humanities & Social Sciences, and from the Strathclyde Business School.

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

Gibson, G.M. and Leach, J. and Keen, S. and Wright, A.J. and Padgett, M.J. (2008) Measuring the accuracy of particle position and force in optical tweezers using high-speed video microscopy. Optics Express, 16 (19). pp. 14561-14570. ISSN 1094-4087

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Abstract

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.