Open AccessSize selective trapping with optical "cogwheel" tweezers
Author(s) -
Alexander Jesacher,
Severin Fürhapter,
Stefan Bernet,
Monika RitschMarte
Publication year - 2004
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/opex.12.004129
Subject(s) - optical tweezers , optics , trapping , diffraction , refractive index , beam (structure) , gaussian beam , microscope , tweezers , materials science , optical force , spatial light modulator , laser , physics , ecology , biology
We experimentally investigate the size-selective trapping behavior of Laguerre-Gaussian beams ("doughnut-beams") and "cogwheel"-shaped beams which are collinear superpositions of two doughnut beams of equal opposite helical index. Experimentally they are created by diffraction of a Gaussian laser beam at a high resolution refractive spatial light modulator (SLM). In the focus of an optical microscope such a beam looks similar to a "cogwheel", i.e. the light intensity is periodically modulated around the circumference of a sphere with a precisely adjustable diameter. In an optical tweezers setup these modes can be used to trap particles or cells, provided their sizes exceed the ring diameter by a fixed amount. This promises a convenient method of constructing an optical tweezers system in microscopy which acts as a passive sorter for particles of differing sizes.