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My sense is also that the new LED sources are brighter than Hg lamps, 
except possibly at the very brightest mercury peaks (365, 546 nm).  For 
GFP, they are for sure brighter.  True LEDs have been somewhat dim in 
the 560 nm range, which is why Lumencor uses an LED-pumped phosphor for 
those wavelengths.  This gives very bright 560 emission.

Kurt

On 11/5/2013 10:21 AM, Armstrong, Brian wrote:
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> Hi Phil I would say that the new LED sources and Light Engines will be brighter than mercury sources. For example I compared an Exfo to a SOLA light engine and the light engine is brighter. The new Lumen Dynamics XLED should provide much better illumination than a mercury source.
> Hopefully, mercury sources will soon be a thing of the past.
> Cheers,
>
> Brian D Armstrong PhD
> Associate Research Professor
> Director, Light Microscopy Core
> Beckman Research Institute
> City of Hope
> Dept of Neuroscience
> 1450 E Duarte Rd
> Duarte, CA 91010
> 626-256-4673 x62872
>
>
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[log in to unmask]] On Behalf Of Philip Oshel
> Sent: Tuesday, November 05, 2013 9:57 AM
> To: [log in to unmask]
> Subject: Brightness difference Hg vs LED
>
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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