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Wednesday, November 23, 2011

Multifocal optical trapping using counter-propagating radially-polarized beams

Yaoju Zhang, Yuxing Dai

A model of optical tweezers which can trap a chain of Rayleigh particles is proposed by using two counter-propagating equal highly focused radial polarized beams. Calculations show that a multifocal distribution along the optical axis is formed and the scattering force is equal to zero in the total focal filed, consequently a chain of metallic Rayleigh particles can be stably trapped. The trap force and the trap stiffness using two counter-propagating Radially-polarized beams are larger than those using two counter-propagating linearly-polarized beams. The trapping stability is calculated and analyzed in detail. The trapping number of particles in a trapping chain can be controlled by adjusting the aperture angle of the objective and the parameters of the filter used in the proposed trap system.

DOI

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