title: Measuring the accuracy of particle position and force in optical tweezers using high-speed video microscopy.
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.
authors.affiliation: Department of Physics and Astronomy, University of Glasgow, Glasgow, UK. g.gibson@physics.gla.ac.uk
authors.forename: Graham M
authors.initials: GM
authors.lastname: Gibson
authors.forename: Jonathan
authors.initials: J
authors.lastname: Leach
authors.forename: Stephen
authors.initials: S
authors.lastname: Keen
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Wright
authors.forename: Miles J
authors.initials: MJ
authors.lastname: Padgett
mesh_terms: D019544:Equipment Failure Analysis / Q000295:instrumentation* / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D018715:Microscopy, Video / Q000295:instrumentation* / Q000379:methods*; D009038:Motion; D052898:Optical Tweezers; D010316:Particle Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical