Don
I have also asked the fundamental question on instrument performance.
How do you know that your confocal is working correctly? Unfortunately
there is not one particle or test that can accomplish this task easily. We
have tried many particles and many tests. Our best test particle  is a 10
micron bead slide made by Jeff Wang of Spereotech.

To evaluate system performance you must consider field illumination,
laser power spectral resolution PMT performance, dichroic filters and
axial resolution, and Noise.  One particle can not accomplish all of these
tests. We are continuing to devise tests that will access the functioning
of our confocal machine.  Our initial attempt to describe the tests
procedures are discussed in an article that will be published this spring.

Zucker, R.M. Price,OT  --Practical Confocal Microscopy and the
Evaluation of System Performance  METHODS of Enzymology Anda
Cornea editor

I hope it brings a suitable discussion among confocal users so
procedures can be adopted that are similar to flow cytometer methods in
evaluating system performance . This is essential if we want to quantify
fluorescence which is one of the aims of our laboratory.




Robert M Zucker. PhD
United States Environmental Protection Agency
National Health and Environmental Effects Research Laboratory
Reproductive Toxicology Division  MD-72
Research Triangle Park North Carolina 27711
tel-- 919-541-1585   fax--919-541-4017