Dear Confocalists- We got some Focalcheck beads recently from Molecular
Probes, and we are testing two of the new water 60x immersion lenses
(Olympus and Zeiss).  I have forgotten any physical chemistry I ever
learned, so would appreciate some help.
1.  If the lens is being immersed in pure water and the specimen in PBS, is
that a sufficient difference in refractive index to cause any distortion?
2.  If one wanted to test the sectioning of the beads at a distance of
50-100 microns from the coverslip, is there anything one can suspend the
beads in that will not cause index mismatch? For instance, what is the
refractive index of an agarose or acrylamide gel, and would that cause a
problem?
3. If either is a problem, could one alter the refractive index of the
mounting solution (say by using sorbitol or sucrose in water) to match the
PBS or agar?  I don't really want sucrose on my lens, but I think it would
be workable if necessary to optimize results.
Thanks- Dave

Dr. David Knecht
Department of Molecular and Cell Biology
University of Connecticut
U-125
Storrs, CT 06269
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