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Optics Express

Optics Express

  • Editor: Michael Duncan
  • Vol. 13, Iss. 24 — Nov. 28, 2005
  • pp: 9695–9701

Switching and measuring a force of 25 femtoNewtons with an optical trap

Alexander Rohrbach  »View Author Affiliations

Optics Express, Vol. 13, Issue 24, pp. 9695-9701 (2005)

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An experiment is described, where an ultra-weak force of 25 femtoNewtons (fN = 10-15 N) displaces a 0.53μm latex bead captured in a soft optical trap. The displacement is measured by exploiting the phase anomaly of the trapping beam, resulting in a small phase shift of the scattered light. The 25fN force stems from the radiation pressure of a nearly collimated second laser beam, which is switched by an accousto-optical modulator. To the best of my knowledge, this is the smallest switchable force which has ever been directly measured.

© 2005 Optical Society of America

OCIS Codes
(140.7010) Lasers and laser optics : Laser trapping
(260.3160) Physical optics : Interference
(290.2200) Scattering : Extinction
(290.4020) Scattering : Mie theory
(290.5850) Scattering : Scattering, particles
(300.2530) Spectroscopy : Fluorescence, laser-induced

ToC Category:
Research Papers

Original Manuscript: October 18, 2005
Revised Manuscript: October 17, 2005
Published: November 28, 2005

Alexander Rohrbach, "Switching and measuring a force of 25 femtoNewtons with an optical trap," Opt. Express 13, 9695-9701 (2005)

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