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Proceedings Paper

Arbitrary multibeam laser scanning and trapping by use of a spatial light modulator and manual scripting interface
Author(s): Xiaodong Xun; Xiaoguang Chang; Doo Jin Cho; Robert W. Cohn
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Paper Abstract

A multi-beam, variable footprint, laser beam steering and shaping system is described and used with a microscope to demonstrate multi-particle laser trapping. It is built around a computer-interfaced 512x512 pixel analog phase-only spatial light modulator (SLM) and a 1 W, 1064 nm wavelength laser. Hand sketches on paper made with a digital pen are used to prescribe the footprints, velocities and trajectories of multiple, independently-controlled diffracted spots. Continuous scanning is approximated by automatically designing a sequence of phase-patterns that are run through and diffracted by the SLM. Very complex scanning sequences of dozens of independently controlled spots can be quickly designed and run. The number of beams that we can trap with is necessarily limited due to the low throughput (~23 mW) of the IR light through the microscope optics. Among the trapping experiments done with the system a triangular shaped vortex ring tends to stop single particles at the apexes of the triangle. However, collision with a second particle pushes the first particle past the apex and sets it into motion, leaving the second particle stopped until collision with a third particle. The discrete motion conditioned on collisions is suggestive of a queuing process or a Markov chain.

Paper Details

Date Published: 18 October 2004
PDF: 7 pages
Proc. SPIE 5514, Optical Trapping and Optical Micromanipulation, (18 October 2004); doi: 10.1117/12.557270
Show Author Affiliations
Xiaodong Xun, Univ. of Louisville (United States)
Xiaoguang Chang, Univ. of Louisville (United States)
Doo Jin Cho, Ajou Univ. (South Korea)
Robert W. Cohn, Univ. of Louisville (United States)

Published in SPIE Proceedings Vol. 5514:
Optical Trapping and Optical Micromanipulation
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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