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Proceedings Paper

Enabling accurate photodiode detection of multiple optical traps by spatial filtering
Author(s): Dino Ott; S. Nader S. Reihani; Lene B. Oddershede
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Paper Abstract

Dual and multiple beam optical tweezers allow for advanced trapping geometries beyond single traps, however, these increased manipulation capabilities, usually complicate the detection of position and force. The accuracy of position and force measurements is often compromised by crosstalk between the detected signals, this crosstalk leading to a systematic error on the measured forces and distances. In dual-beam optical trapping setups, the two traps are typically orthogonal polarized and crosstalk can be minimized by inserting polarization optics in front of the detector, however, this method is not perfect because of the de-polarization of the trapping beam introduced by the required high numerical aperture optics. Moreover, the restriction to two orthogonal polarisation states limits the number of detectable traps to two. Here, we present an easy-to-implement simple method to efficiently eliminate cross-talk in dual beam setups.1 The technique is based on spatial filtering and is highly compatible with standard back-focal-plane photodiode based detection. The reported method significantly improves the accuracy of force-distance measurements, e.g., of single molecules, hence providing much more scientific value for the experimental efforts. Furthermore, it opens the possibility for fast and simultaneous photodiode based detection of multiple holographically generated optical traps.

Paper Details

Date Published: 16 September 2014
PDF: 6 pages
Proc. SPIE 9164, Optical Trapping and Optical Micromanipulation XI, 916411 (16 September 2014); doi: 10.1117/12.2064645
Show Author Affiliations
Dino Ott, Univ. of Copenhagen (Denmark)
S. Nader S. Reihani, Sharif Univ. of Technology (Iran, Islamic Republic of)
Niels Bohr Institute (Denmark)
Lene B. Oddershede, Univ. of Copenhagen (Denmark)

Published in SPIE Proceedings Vol. 9164:
Optical Trapping and Optical Micromanipulation XI
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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