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Proceedings Paper

Real-time control of optical tweezers
Author(s): Anders E. Wallin; Heikki Ojala; Anders Korsbäck; Edward Haeggström; Roman Tuma
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Paper Abstract

Optically trapped microshperes can be manipulated by steering the trap beam, while the object position is measured with sub-nanometer resolution. A fast steering system is required to create feedback loop for measurements at a constant force or to increase position detection precision by trap stiffening. Using a real-time re-programmable digital signal processor, we combine steering and position detection to create a fast and versatile closed-loop feedback controlled instrument. We describe the construction and calibration of the instrument. We show that a proportional gain position-clamp algorithm can achieve about 10-fold increase in effective trap stiffness while higher gains lead to unwanted resonances.

Paper Details

Date Published: 5 September 2007
PDF: 8 pages
Proc. SPIE 6644, Optical Trapping and Optical Micromanipulation IV, 66441Y (5 September 2007); doi: 10.1117/12.737269
Show Author Affiliations
Anders E. Wallin, Univ. of Helsinki (Finland)
Heikki Ojala, Univ. of Helsinki (Finland)
Anders Korsbäck, Univ. of Helsinki (Finland)
Edward Haeggström, Univ. of Helsinki (Finland)
Roman Tuma, Univ. of Helsinki (Finland)

Published in SPIE Proceedings Vol. 6644:
Optical Trapping and Optical Micromanipulation IV
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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