Optimization of probe-laser focal offsets for single-particle tracking

Ai Tang Chang, Yi-Ren Chang, Sien Chi, Long Hsu

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

In optical tweezers applications, tracking a trapped particle is essential for force measurement. One of the most popular techniques for single-particle tracking is achieved by analyzing the forward and backward light pattern, scattered by the target particle trapped by a trap laser beam, of an additional probelaser beam with different wavelength whose focus is slightly apart from the trapping center. However, the optimized focal offset has never been discussed. In this paper, we investigate the tracking range and sensitivity as a function of the focal offset between the trapping and the probe-laser beams. As a result, the optimized focal offsets are a 3.3-fold radius ahead and a 2.0-fold radius behind the trapping laser focus in the forward tracking and the backward tracking, respectively. The experimental result agrees well with a theoretical prediction using the Mie scattering theory.

Original languageEnglish
Pages (from-to)5643-5648
Number of pages6
JournalApplied Optics
Volume51
Issue number23
DOIs
Publication statusPublished - 2012 Aug 10

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optimization
probes
trapped particles
lasers
trapping
laser beams
radii
Mie scattering
traps
sensitivity
predictions
wavelengths

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering

Cite this

Optimization of probe-laser focal offsets for single-particle tracking. / Chang, Ai Tang; Chang, Yi-Ren; Chi, Sien; Hsu, Long.

In: Applied Optics, Vol. 51, No. 23, 10.08.2012, p. 5643-5648.

Research output: Contribution to journalArticle

Chang, Ai Tang ; Chang, Yi-Ren ; Chi, Sien ; Hsu, Long. / Optimization of probe-laser focal offsets for single-particle tracking. In: Applied Optics. 2012 ; Vol. 51, No. 23. pp. 5643-5648.
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