Regular papers

Independent trapping, manipulation and characterization by an all-optical biophotonics workstation

¹ Department of Physics and Astronomy, University of Aarhus, 8000 Aarhus C, Denmark
² Department of Chemistry, University of Aarhus, 8000 Aarhus C, Denmark
³ Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, 8000 Aarhus C, Denmark
⁴ DTU Fotonik, Department of Photonics Engineering, Technical University of Denmark, 4000 Roskilde, Denmark

^a keiding@chem.au.dk
^b henriks@chem.au.dk
^c jesper.gluckstad@fotonik.dtu.dk

Received: 8 August 2008

Abstract

Optical trapping has enabled a multitude of applications focusing, in particular, on non-invasive studies of cellular material. The full potential of optical trapping has, however, not yet been exploited due to restricted access to the trapped samples, caused by high numerical aperture objectives needed to focus the trapping laser beams. Here, we use our recently developed biophotonics workstation to overcome this limitation by introducing probing and spectroscopic characterization of optically trapped particles in a side-view geometry perpendicular to the trapping beams rather than in the traditional top-view geometry parallel to the trapping beams. Our method is illustrated by CARS and fluorescence spectroscopy of trapped polystyrene beads. The side-view geometry opens intriguing possibilities for accessing trapped particles with optical as well as other types of probe methods independent from the trapping process.