title: Characterization of microparticles with driven optical tweezers.
abstract: We discuss how actively-driven optical tweezers may be used to characterize Brownian microparticles. Two experiments are described in detail. We follow the thermal fluctuations of a charged particle in an oscillatory electric field and demonstrate that charges as low as a few elementary charges can be measured accurately and reproducibly. Secondly, we measure the orientational dynamics of a trapped rotating droplet and use circular polarimetry within optical tweezers to determine in situ birefringence.
authors.affiliation: School of Chemistry, University of Bristol, Bristol, UK.
authors.forename: Tiffany A
authors.initials: TA
authors.lastname: Wood
authors.forename: G Seth
authors.initials: GS
authors.lastname: Roberts
authors.forename: Sarayoot
authors.initials: S
authors.lastname: Eaimkhong
authors.forename: Paul
authors.initials: P
authors.lastname: Bartlett