Three-dimensional force measurements in optical tweezers formed with high-NA micromirrors.
The three-dimensional trap stiffness of optical tweezers formed with high-NA micromirrors is investigated by back-focal-plane interferometry and power spectrum analysis. Normalized stiffness values of kappaxy/Ptrap=1.2(microN/m)/mW and kappaz/Ptrap=0.52(microN/m)/mW in the transverse and axial directions, respectively, have been measured for polystyrene spheres with a radius of 1.03 microm. Compared with high-NA microscope objectives, micromirrors achieve much better trapping performances, particularly in the axial direction.
Merenda
Fabrice
F
Advanced Photonics Laboratory, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland. fabrice.merenda@a3.epfl.ch
Grossenbacher
Mathieu
M
Jeney
Sylvia
S
Forró
László
L
Salathé
René-Paul
RP