Optical feedback tweezers

Avinash Kumar; John Bechhoefer

doi:10.1117/12.2323837

7 September 2018 Optical feedback tweezers

Avinash Kumar, John Bechhoefer

Proceedings Volume 10723, Optical Trapping and Optical Micromanipulation XV; 107232J (2018) https://doi.org/10.1117/12.2323837
Event: SPIE Nanoscience + Engineering, 2018, San Diego, California, United States

Abstract

Feedback traps can manipulate particles arbitrarily. In a feedback trap, a position detector detects the particle’s position, a computer calculates the necessary force to be applied based on the position in the “virtual potential,” which is applied to the particle. The process is repeated with as fast a loop rate as practical. Previous feedback traps have used electrokinetic or hydrodynamic forces to manipulate particles. Here, an optical trap creates the force used by the feedback trap to impose arbitrary potentials. We create feedback forces on optically trapped particles by moving the trap position rapidly in response to observed fluctuations with the help of an acoustooptic deflector (AOD). In preliminary experiments, we have confined a 1.5 μm silica bead in a virtual potential that is 35-40 times stiffer than the underlying optical trap, whose laser power is kept constant. We also create a virtual double-well potential with independent control over the well separation and barrier height, which is impossible to do with time-sharing optical tweezers.

Citation Download Citation

Avinash Kumar and John Bechhoefer "Optical feedback tweezers", Proc. SPIE 10723, Optical Trapping and Optical Micromanipulation XV, 107232J (7 September 2018); https://doi.org/10.1117/12.2323837

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