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Proceedings Paper

Non-contact optical control of multiple particles and defects using holographic optical trapping with phase-only liquid crystal spatial light modulator
Author(s): Suman Anand; Rahul P. Trivedi; Gabriel Stockdale; Ivan I. Smalyukh
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Paper Abstract

In this work, three-dimensional manipulation of multiple defects and structures is performed in the framework of holographic optical trapping approach using a spatial light modulator. A holographic optical tweezers system is constructed using a liquid crystal spatial light modulator to generate multiple optical traps. We optimize the tweezers setup to perform polarization-sensitive holographic optical trapping and then explore properties of optical trapping in thermotropic liquid crystals and compare them to the case of isotropic fluids. One of the major challenges complicating the quantitative measurements in these fluids is the anisotropic nature of the liquid crystal medium, which makes the tight focusing of the laser beam difficult and considerably weakens optical trapping forces. Using liquid crystals with low birefringence allows us to mitigate these artefacts. Optical trapping forces and the trap stiffness are first calibrated for different laser powers using viscous drag forces. This is then used to probe inter-particle and defect-particle interaction forces as well as to characterize tension of line defects in the bulk of liquid crystals.

Paper Details

Date Published: 3 February 2009
PDF: 15 pages
Proc. SPIE 7232, Emerging Liquid Crystal Technologies IV, 723208 (3 February 2009); doi: 10.1117/12.807873
Show Author Affiliations
Suman Anand, Univ. of Colorado at Boulder (United States)
Amity Univ. (India)
Rahul P. Trivedi, Univ. of Colorado at Boulder (United States)
Gabriel Stockdale, Univ. of Colorado at Boulder (United States)
Ivan I. Smalyukh, Univ. of Colorado at Boulder (United States)

Published in SPIE Proceedings Vol. 7232:
Emerging Liquid Crystal Technologies IV
Liang-Chy Chien; Ming Hsien Wu, Editor(s)

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