Abstract
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 μm 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.
© 2006 Optical Society of America
Full Article | PDF ArticleMore Like This
Alexander Rohrbach and Ernst H. K. Stelzer
Appl. Opt. 41(13) 2494-2507 (2002)
Erik Fällman and Ove Axner
Appl. Opt. 42(19) 3915-3926 (2003)
Maria Dienerowitz, Graham Gibson, Richard Bowman, and Miles Padgett
Opt. Express 19(24) 24589-24595 (2011)