Interferometric tracking of optically trapped probes behind structured surfaces: A phase correction method.
We investigate the influence of an additional scatterer on the tracking signal of an optically trapped particle. The three-dimensional particle position is recorded interferometrically with nanometer precision by using a quadrant photodiode in the back focal plane of a detection lens. A phase disturbance underneath the sample leads to incorrect position signals. The resulting interaction potential and forces are therefore erroneous as well. We present a procedure to correct for the disturbance by measuring its interferometric signal. We prove the applicability of our phase correction approach by generating a defined displacement of the trapped probe.
Seitz
Peter C
PC
European Molecular Biology Laboratory, Meyerhofstrasse 1, D-69117 Heidelberg, Germany. p.seitz@gmx.net
Stelzer
Ernst H K
EH
Rohrbach
Alexander
A