title: Longer axial trap distance and larger radial trap stiffness using a double-ring radially polarized beam.
abstract: The optical trapping forces acting on a metallic Rayleigh particle are calculated for the case where a double-ring-shaped radially polarized beam is applied. The influence of the off-focus distance and the off-axis distance of a trapping particle on the trapping force is investigated. Compared with the use of the conventional single-ring-shaped radially polarized beam, the longer axial trap distance and the larger radial trap stiffness are predicted using a double-ring-shaped radially polarized beam in an optical trap. These features are useful for improving the trapping ability of an optical trap system where a longer axial trap distance is needed.
authors.affiliation: College of Physics and Electronic Information, Wenzhou University, Wenzhou 325035, China. zhangyaoju@sohu.com
authors.forename: Yaoju
authors.initials: Y
authors.lastname: Zhang
authors.forename: Taikei
authors.initials: T
authors.lastname: Suyama
authors.forename: Biaofeng
authors.initials: B
authors.lastname: Ding