title: Light streak tracking of optically trapped thin microdisks.
abstract: Nonspherical particles can uniquely probe soft system dynamics. We show that laser tweezers stably trap thin coinlike microdisks in 3D with an edge-on orientation. Scattered light forms a streak that we track using a fast camera to measure the disk's angular displacement. Linearly polarized tweezers rotationally trap a birefringent disk, and we measure its harmonically bound Brownian rotation over 5 decades in time. Near a surface, the disk exhibits a translational-orientational switchback oscillation. Circularly polarized tweezers rotate the disk and streak, yielding a colloidal lighthouse.
authors.affiliation: Corporate Strategic Research, ExxonMobil Research and Engineering Company, Route 22 East, Annandale, New Jersey 08801, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Cheng
authors.forename: P M
authors.initials: PM
authors.lastname: Chaikin
authors.forename: T G
authors.initials: TG
authors.lastname: Mason