Optical trap stiffness in the presence and absence of spherical aberrations

Optical traps are commonly constructed with high-numerical-aperture objectives. Oil-immersion objectives suffer from spherical aberrations when used for imaging in aqueous solutions. The effect of spherical aberrations on trapping strength has been modeled by approximation, and only a few experiment...

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Bibliographic Details
Published in:Applied optics (2004) 2006-03, Vol.45 (8), p.1812-1819
Main Authors: Vermeulen, Karen C, Wuite, Gijs J L, Stienen, Ger J M, Schmidt, Christoph F
Format: Article
Language:English
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Summary:Optical traps are commonly constructed with high-numerical-aperture objectives. Oil-immersion objectives suffer from spherical aberrations when used for imaging in aqueous solutions. The effect of spherical aberrations on trapping strength has been modeled by approximation, and only a few experimental results are available in the case of micrometer-sized particles. We present an experimental study of the dependence of lateral and axial optical-trap stiffness on focusing depth for polystyrene and silica beads of 2 microm diameter by using oil- and water-immersion objectives. We demonstrate a strong depth dependence of trap stiffness with the oil-immersion objective, whereas no depth dependence was observed with the water-immersion objective.
ISSN:1559-128X
DOI:10.1364/ao.45.001812