Posted by
James Pawley on
URL: http://confocal-microscopy-list.275.s1.nabble.com/LEDs-tp4283200p7313637.html
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>Hello Jacques,
>
>How much power you get at the sample will depend
>to some degree on the light path and light
>delivery system of your specific microscope, in
>addition to the light source itself.
>
>The only LED system we have is the Insight SSI
>(solid state illuminator) on our DeltaVision
>system. It has LEDs rated from 22 mW (505-515
>nm) to 89 mW (563-588 nm). I am assuming these
>are nominal LED output power levels, although
>the brochure does not specify. For our lines, we
>measured 20 to 50 mW at the sample, or about
>35-50% of the rated power for any given line,
>which would be really good delivery efficiency
>(our laser scanning confocal is about 10%). This
>is several times the power levels we were
>getting with a conventional mercury bulb and
>excitation filters on a comparable (but not
>identical) system (about 6 to 20 mW depending on
>excitation filter used, if I remember
>correctly). For most wavelengths, this is as
>bright or brighter than our Exfo or Xenon
>illuminators, which are typically brighter (at
>the sample) than our older Hg bulb illuminators.
>However, these illumination systems are also
>installed on newer microscopes with possibly
>improved light delivery. We haven't had the
>system for long enough to encounter any
>potential issues, but we like the brightness and
>the speed of wavelength switching. Also, we do
>not have to worry about burned out excitation
>filters or UV leaking, and we do not have to
>worry about replacing bulbs, heat, or keeping
>track of when lamps are turned on and off.
>Also, no worries about anyone forgetting to turn
>off the lamp on Friday night. I can't think of
>any downside at this time. My second choice in
>terms of convenience would be the Exfo or
>similar systems (long life and easy to replace
>bulbs, combined with good brightness).
>
>For reference, the InsightSSI specs can be found here:
>
>
http://www.api.com/downloads/pdfs/lifescience/InsightSSI.pdf>
>
>Julio Vazquez
>Fred Hutchinson Cancer Research Center
>Seattle, WA
>
>
http://www.fhcrc.org>
>==
Dear Julio,
Thank you so much for putting some actual
measurements into this important discussion.
Could I ask you for a few more details?
I assume that you did these tests with the same
objective, or at least with an objective with the
same NA and mag (and hence the same size and
location of the BFP. Light that hits the metal
will not pass through the objective). Assuming
that you measured light coming out of the
objective with some sort of photometer, the other
big variable is how you set the size of the field
diaphragm (referred to the image plane: For
instance, you might set it to be the same as the
field of view of a particular objective, or maybe
to some known and repeatable fraction thereof.)
Also, with respect to your comment on confocal
performance, I am assuming that the 10%
efficiency refers to the fraction of the light
leaving the laser that arrives at the focus
plane. Ten percent seems low and seems to suggest
to me that either the optics used to launch the
laser light into the fiber are not well aligned
or that the optics are set up to over-fill the
BFP of the particular objective used for the
test. Otherwise it is hard to see where so much
power would be lost: objective transmissions are
now usually quoted in the 80-90% range, and a
properly chosen dichroic should be about the same
while beam-steering mirrors and galvo mirrors
should be about 99%.
In any case, thank you for the numbers.
Regards,
Jim Pawley
***************************************************************************
Prof. James B. Pawley,
Ph. 608-238-3953
21. N. Prospect Ave. Madison, WI 53726 USA
[hidden email]
3D Microscopy of Living Cells Course, June 9-21, 2012, UBC, Vancouver Canada
Info:
http://www.3dcourse.ubc.ca/
Application deadline 3/16/2012
"If it ain't diffraction, it must be statistics." Anon. 11/16/12
>
>
>On Feb 22, 2012, at 2:07 AM, jacques wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
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>>
>> Hi all,
>>
>> two years later, and a quite similar question.
>>
>> I use a Zeiss epifluorescence microscope, and I'm thinking to replace my HBO
>> housing by a LED multicolor source.
>> Of course, Zeiss sells the colibri setup, but the choice on the market is
>> growing day after day, and for example, Thorlabs also sells something with 4
>> colors and a control unit, with the Zeiss mounting system.
>> I'm sure many other manufacturers do the same.
>>
>> Do anybody compared the HBO to a LED system for classical epifluorescence ?
>> What should be the LED power to have something similar to a 100W at common
>> wavelenghts (dapi, gfp, rhodamine, etc) ? Even after checking this page :
>>
http://www.olympusfluoview.com/theory/noncoherentsources.html>> It is still difficult to know which valeus and units should be considered...
>>
>> Thanks for the help
>>
>> J.
>>
>>
>> -----
>>
>> Jacques FATTACCIOLI
>>
>> Département de Chimie
>> Ecole Normale Supérieure
>> 24 rue Lhomond 75231 Paris Cedex 05
>> Email :
[hidden email]
>> Web :
http://jacquesfattaccioli.wordpress.com>> --
>> View this message in context:
>>
http://confocal-microscopy-list.588098.n2.nabble.com/LEDs-tp4283200p7307846.html>> Sent from the Confocal Microscopy List mailing list archive at Nabble.com.
--
***************************************************************************
Prof. James B. Pawley,
Ph. 608-238-3953
21. N. Prospect Ave. Madison, WI 53726 USA
[hidden email]
3D Microscopy of Living Cells Course, June 9-21, 2012, UBC, Vancouver Canada
Info:
http://www.3dcourse.ubc.ca/
Application deadline 3/16/2012
"If it ain't diffraction, it must be statistics." Anon. 11/16/12