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Proceedings Paper

Laser tweezing near resonance absorption
Author(s): Rodney R. Agayan; Christoph F. Schmidt; Fred Gittes; Raoul Kopelman
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Paper Abstract

Expressions for radiation-induced forces are presented for the case of a Rayleigh particle at the focus of a Gaussian laser beam. Classical electromagnetic theory was used to obtain the dependence of the scattering and gradient forces on the incident laser frequency, beam convergence angle, and spatial position of the particle in the focus. Numerical analysis performed for particles with a single resonant absorption peak demonstrates the occurrence of enhanced trapping forces at near-resonant frequencies. An indication of the breakdown of the paraxial Gaussian approximation for large convergence angles is also shown by calculation of the scattering force. Use of this technique of gradient force enhancement may provide optical tweezers with enhanced trapping strengths and a degree of specificity.

Paper Details

Date Published: 2 November 2001
PDF: 11 pages
Proc. SPIE 4431, Photon Migration, Optical Coherence Tomography, and Microscopy, (2 November 2001); doi: 10.1117/12.447444
Show Author Affiliations
Rodney R. Agayan, Univ. of Michigan (United States)
Christoph F. Schmidt, Vrije Univ. Amsterdam (United States)
Fred Gittes, Washington State Univ. (United States)
Raoul Kopelman, Univ. of Michigan (United States)


Published in SPIE Proceedings Vol. 4431:
Photon Migration, Optical Coherence Tomography, and Microscopy
Stefan Andersson-Engels; Michael F. Kaschke, Editor(s)

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