Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Opt Lett. 2005 Jun 1;30(11):1318-20.

Measurement of the effective focal shift in an optical trap.

Author information

  • 1Department of Biological Sciences, Stanford University, Stanford, California 94305-5020, USA.

Abstract

The focus of an oil-immersion microscope objective is shifted because of the refractive-index mismatch between the cover glass and the aqueous sample. We present a procedure with which to determine the focal shift by use of an inverted microscope equipped with optical tweezers. As the position of the sample chamber is scanned vertically, we measure the axial displacement of an optically trapped bead; the relative motion of the bead with respect to the surface supplies the effective focal shift. Measurements of this quantity deviate from electromagnetic calculations of the focal shift, a discrepancy attributable to the depth-dependent decrease in axial trap stiffness that arises from spherical aberration.

PMID:
15981519
[PubMed]
PMCID:
PMC1483143
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for Optical Society of America Icon for PubMed Central
    Loading ...
    Write to the Help Desk