Influence of the condenser on sample tracking via forward scattering pattern detection

Che Liang Tsai*, Bo Jui Chang, Kuang Lung Huang, Long Hsu

*Corresponding author for this work

Research output: Contribution to journalConference article

Abstract

Sample tracking with a high spatial sensitivity is highly desired in force measurement with optical tweezers. However, the trick that sample tracking via forward scattering pattern detection would provide a higher sensitivity than that via regular image detection has never been investigated. In this paper, we systematically study the influences of the position and the numerical aperture of the condenser on sample tracking via forward scattering pattern detection. In our experiment, a 60X condenser is used to form the forward scattering pattern of a sample bead upon a CCD camera. As the bead is transversely shifted at a step size of 30nm by a PZT XYZ stage, we measure the magnitude of the corresponding shift of the forward scattering pattern when the 60X condenser of different angular apertures is placed at various locations along the optical axis. Our result shows that the most sensitive forward scattering pattern occurs when the condenser collimates the forward scattering light from the sample bead. We also find that the larger the numerical aperture is, the higher the sensitivity of forward scattering pattern detection will be.

Original languageEnglish
Article number54
Pages (from-to)393-401
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5514
DOIs
StatePublished - 1 Dec 2004
EventOptical Trapping and Optical Micromanipulation - Denver, CO, United States
Duration: 2 Aug 20046 Aug 2004

Keywords

  • And numerical aperture
  • Condenser
  • Forward scattering pattern
  • Optical tweezers
  • Sample tracking

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