Characterization of trapping force in the presence of spherical aberration

Pu Chun Ke, Min Gu

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Transverse trapping force in laser tweezers is investigated in the presence of spherical aberration caused by the refractive-index mismatch between a cover slip and the water solution where particles are suspended. The transverse trapping efficiency is characterized in terms of the numerical aperture of a microscope objective and the thickness of a sample cell. It has been experimentally demonstrated that the spherical aberration can be compensated for by changing the effective tube length of an objective used for trapping. As a result, the transverse trapping efficiency can be improved by up to 20%. In principle, a further improvement in the trapping efficiency is possible if an objective of an infinitely-long tube length is used.

Original languageEnglish
Pages (from-to)2159-2168
Number of pages10
JournalJournal of Modern Optics
Issue number10
Publication statusPublished - 1 Jan 1998
Externally publishedYes

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