Here is some information about my illumination techniques and apparatus.
The yeast I am screening have an S65T version of GFP which has an
excitation wavelength of 488nm and an emission wavelength of 512nm. For
illumination I use a Kodak 4400 slide projector with an optical filter in
the slide slot. There is nothing special about the slide projector that I
know of; I think that any one with a decent bulb will work. The filter
is a 488DF22 narrow bandpass filter from Omega Optical (802/254-2690)
matched to the excitation wavelength of the S65T gfp (488nm). The filter
I have is a 50mmX50mm square, the size of a slide. It has low band
blocking on it so that it will not transmit red light. Since the 488nm blue
illuminating light is visible, a filter is needed to view the much less
intense 512nm green fluorescence. I use two Kodak No.12 gelatin filters
taped to a UV face sheild. The UV face sheild is not needed but it is a
convinient way to hold the filters.
THis is definitely not the most sensitive way to detect
fluorescence. I can detect much weaker fluorescence at the cell level
using a fluorescence mircroscope or FACS, but I does work for my purposes.
I hope this information will help.
scronin at jeeves.ucsd.edu