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Sunday, April 1, 2012

Optical force lateral push–pulling using focus positioning

Murat Muradoglu, Wesley Sung-Yee Chiu, and Tuck Wah Ng

The placement of the beam focus corresponding with the center of living matter (such as cells) in an optical tweezer can result in photodamage. We advance a scheme here that locates the focus of the beam either above or below the matter to pull and push relative to the beam axis in a predominant lateral sense based on the resultant action of scattering and gradient forces. Switching to a laser that acts oppositely serves to restore the axial position of the matter. Although an exact value could not be derived due to the statistical nature of Brownian perturbations and time frame considerations, we simulated the optical force fields to visualize the effective force envelope. The lateral optical push–pull operation was conducted experimentally on polystyrene beads in which the motion manipulation efficacy was characterized.

DOI

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