Optical force field mapping in microdevices.
We present a method for characterizing microscopic optical force fields. Two dimensional vector force maps are generated by measuring the optical force applied to a probe particle for a grid of particle positions. The method is used to map out the force field created by the beam from a lensed fiber inside a liquid filled microdevice. We find transverse gradient forces and axial scattering forces on the order of 2 pN per 10 mW laser power which are constant over a considerable axial range (>35 microm). These findings suggest future useful applications of lensed fibers for particle guiding/sorting. The propulsion of a small particle at a constant velocity of 200 microm s(-1) is shown.
Knöner
Gregor
G
Centre for Biophotonics and Laser Science, School of Physical Sciences, The University of Queensland, Brisbane 4072, QLD, Australia. knoener@physics.uq.edu.au
Ratnapala
Adrian
A
Nieminen
Timo A
TA
Vale
Chris J
CJ
Heckenberg
Norman R
NR
Rubinsztein-Dunlop
Halina
H
D007834:Lasers; D008855:Microscopy, Electron, Scanning / Q000295:instrumentation / Q000379:methods; D055095:Optics and Photonics; D012680:Sensitivity and Specificity