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Proceedings Paper

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

Paper Details

Date Published: 18 October 2004
PDF: 9 pages
Proc. SPIE 5514, Optical Trapping and Optical Micromanipulation, (18 October 2004); doi: 10.1117/12.559535
Show Author Affiliations
Che-Liang Tsai, National Chiao Tung Univ. (Taiwan)
Bo-Jui Chang, National Chiao Tung Univ. (Taiwan)
Kuang-Lung Huang, Hsiuping Institute of Technology (Taiwan)
Long Hsu, National Chiao Tung Univ. (Taiwan)


Published in SPIE Proceedings Vol. 5514:
Optical Trapping and Optical Micromanipulation
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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