"Carlos P. Rubbi" <[log in to unmask]> writes:

> Yes, it would. In the first half of the bead (the one closer to the
> objective) the beam should travel mostly trough medium (depending on the
> NA). But for the second half, the RI mistmatch between the bead and the
> medium is likely to stretch/shrink the hemisphere (depending on the RI
> ratio).
>
> Carlos

You should be able to check an effect like that with those large fluorescent
spheres (~15um) that are only stained on the surface (I think some other
posting in this or a similiar thread mentioned those to be distributed by Mol.
Probes). A zscan through such a bead would in that case probably show
something like a ring that is more or less egg shaped (i.e. higher curvature
on one side than on the other due to focus shift) and more fuzzy in
the direction further away from the objective (effective spherical
aberration). I seem to remember that I have seen an image like that in
some paper some time ago.

  Christian

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Christian Soeller                         mailto: [log in to unmask]
St. Georges Hospital Medical School       Dept. of Pharmacology
Cranmer Terrace                           London SW17 0RE