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

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

Research output: Contribution to journalConference articlepeer-review


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 (US)
Article number54
Pages (from-to)393-401
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2004
Externally publishedYes
EventOptical Trapping and Optical Micromanipulation - Denver, CO, United States
Duration: Aug 2 2004Aug 6 2004


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

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Influence of the condenser on sample tracking via forward scattering pattern detection'. Together they form a unique fingerprint.

Cite this