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Hi Phil,

Current LED light sources can be brighter and (should have) more stable 
light output (and "instant" on/off, and less heat output and less ozone 
and no chance of the bulb exploding ... "do not look at top of arc lamp 
with remaining eye". Also many LEDs have precise - and reproducible - 
voltage control. Purchase price will eventually be made up in total cost 
of ownership.

Brighter light sources enable selection of narrower wavelength range, 
for example, at the excitation peak of the desired fluorophore (and 
hopefully minima of unwanted fluorophores), leaving more room for 
emission wavelength range.

George

On 11/5/2013 11:56 AM, Philip Oshel wrote:
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> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
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>
> All,
>
> I had this question put to me by a new faculty member, and don't have 
> a ready answer:
> "Is there a ballpark percentage for how much less bright an LED vs a 
> standard mercury lamp light?"
> This is for regular epifluorescence, not confocal.
>
> This is in the realm of arm-waving over a picture of beer (a good, 
> dark stout), ignoring brands, how old the Hg bulb is, ex/em cubes, 
> which part of the spectrum is used, and all that. Personally, I'd 
> think the answer is more like, "Doesn't matter, the dimmer system is 
> still too bright to use all the available light and not damage the 
> specimen." But ... ?
>
> Phil


-- 



George McNamara, Ph.D.
Single Cells Analyst
L.J.N. Cooper Lab
University of Texas M.D. Anderson Cancer Center
Houston, TX 77054
Tattletales http://works.bepress.com/gmcnamara/26/