Brightness difference Hg vs LED

[Oshel, Philip Eugene]

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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
--
Philip Oshel
Microscopy Facility Supervisor
Biology Department
024C Brooks Hall
Central Michigan University
Mt. Pleasant, MI 48859
[phone]

[Armstrong, Brian]

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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:[hidden email]] On Behalf Of Philip Oshel
Sent: Tuesday, November 05, 2013 9:57 AM
To: [hidden email]
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
--
Philip Oshel
Microscopy Facility Supervisor
Biology Department
024C Brooks Hall
Central Michigan University
Mt. Pleasant, MI 48859
[phone]


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[Doube, Michael]

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Hi Phil,

no idea about percentages but in my hands a single blue high power LED
like this one, is 'enough' for practical application, when set directly
in place of a 50W Hg lamp, on a heatsink in the lamphouse:

http://uk.rs-online.com/web/p/visible-leds/7393548/  (no commercial
interest)

Provided of course that you only want blueish excitation...

You can also run them off very simple and cheap switching boxes, if you
are not afraid of a soldering iron.

Michael

On 05/11/13 18:00, Philip Oshel wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> 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

--
Dr Michael Doube
BPhil BVSc PhD MRCVS
Lecturer, Comparative Biomedical Sciences
The Royal Veterinary College
London NW1 0TU
United Kingdom

[phone]

[RVC Logo - link to RVC Website]<http://www.rvc.ac.uk>    [Twitter icon - link to RVC (Official) Twitter] <http://twitter.com/RoyalVetCollege>     [Facebook icon - link to RVC (Official) Facebook] <http://www.facebook.com/theRVC>     [YouTube icon - link to RVC YouTube] <http://www.youtube.com/user/RoyalVetsLondon?feature=mhee>     [Pinterest icon - link to RVC Pinterest] <http://pinterest.com/royalvetcollege/>     [Instagram icon - link to RVC Instagram] <http://instagram.com/royalvetcollege>

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[Kurt Thorn]

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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:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> 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:[hidden email]] On Behalf Of Philip Oshel
> Sent: Tuesday, November 05, 2013 9:57 AM
> To: [hidden email]
> Subject: Brightness difference Hg vs LED
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> 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

[Julio Vazquez]

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A quick comparison in our lab gave the following:

488 nm (FITC) band of an LED-based light engine (Lumencor): 40 mW
300 W Xenon Sutter illuminator (probably our brightest light source) with FITC EX filter: 70 mW

both measured at the exit of the fiber or light guide.

I agree that LED based light engines are probably at least as good (power-wise) as most lamps, plus they have other benefits. Charts such as the one found here should be a good guide regarding relative power:

http://lumencor.com/wp-content/uploads/2011/09/SpectraX-LE-User-Manual1.pdf


Julio Vazquez, PhD
Fred Hutchinson Cancer Research Center
Seattle, WA 98109

http://www.fhcrc.org/en.html




On Nov 5, 2013, at 1:50 PM, Kurt Thorn wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> 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:
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> 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:[hidden email]] On Behalf Of Philip Oshel
>> Sent: Tuesday, November 05, 2013 9:57 AM
>> To: [hidden email]
>> Subject: Brightness difference Hg vs LED
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> 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

[mcammer]

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How much of the 70 mW is from UV or IR leaking through?
_________________________________________
Michael Cammer, Assistant Research Scientist
Skirball Institute of Biomolecular Medicine
Lab: [phone]  Cell: [phone]

________________________________________
From: Confocal Microscopy List [[hidden email]] on behalf of Julio Vazquez [[hidden email]]
Sent: Tuesday, November 05, 2013 5:09 PM
To: [hidden email]
Subject: Re: Brightness difference Hg vs LED


A quick comparison in our lab gave the following:

488 nm (FITC) band of an LED-based light engine (Lumencor): 40 mW
300 W Xenon Sutter illuminator (probably our brightest light source) with FITC EX filter: 70 mW

both measured at the exit of the fiber or light guide.

I agree that LED based light engines are probably at least as good (power-wise) as most lamps, plus they have other benefits. Charts such as the one found here should be a good guide regarding relative power:

http://lumencor.com/wp-content/uploads/2011/09/SpectraX-LE-User-Manual1.pdf


Julio Vazquez, PhD
Fred Hutchinson Cancer Research Center
Seattle, WA 98109

http://www.fhcrc.org/en.html


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=================================

[George McNamara]

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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:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> 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/

[Mark Cannell-2]

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Almost none, the Sutter uses common narrow band interference filters that are well blocked outside the pass band. As you raised this question, I wonder how much heat comes from a LED source -the chip gets very hot in high power applications and about half the power consumption of a LED is waste heat…

Cheers M

 
On 6/11/2013, at 1:48 am, Cammer, Michael <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> How much of the 70 mW is from UV or IR leaking through?
> _________________________________________
> Michael Cammer, Assistant Research Scientist
> Skirball Institute of Biomolecular Medicine
> Lab: [phone]  Cell: [phone]
>
> ________________________________________
> From: Confocal Microscopy List [[hidden email]] on behalf of Julio Vazquez [[hidden email]]
> Sent: Tuesday, November 05, 2013 5:09 PM
> To: [hidden email]
> Subject: Re: Brightness difference Hg vs LED
>
>
> A quick comparison in our lab gave the following:
>
> 488 nm (FITC) band of an LED-based light engine (Lumencor): 40 mW
> 300 W Xenon Sutter illuminator (probably our brightest light source) with FITC EX filter: 70 mW
>
> both measured at the exit of the fiber or light guide.
>
> I agree that LED based light engines are probably at least as good (power-wise) as most lamps, plus they have other benefits. Charts such as the one found here should be a good guide regarding relative power:
>
> http://lumencor.com/wp-content/uploads/2011/09/SpectraX-LE-User-Manual1.pdf
>
>
> Julio Vazquez, PhD
> Fred Hutchinson Cancer Research Center
> Seattle, WA 98109
>
> http://www.fhcrc.org/en.html
>
>
> ------------------------------------------------------------
> This email message, including any attachments, is for the sole use of the intended recipient(s) and may contain information that is proprietary, confidential, and exempt from disclosure under applicable law. Any unauthorized review, use, disclosure, or distribution is prohibited. If you have received this email in error please notify the sender by return email and delete the original message. Please note, the recipient should check this email and any attachments for the presence of viruses. The organization accepts no liability for any damage caused by any virus transmitted by this email.
> =================================

Mark  B. Cannell Ph.D. FRSNZ
Professor of Cardiac Cell Biology
School of Physiology &  Pharmacology
Medical Sciences Building
University of Bristol
Bristol
BS8 1TD UK

[hidden email]

[Watkins, Simon C]

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We actually did a lot of work on this a year or so back.  Specifically
with the Lumencor Spectra X.  There is a lot more power with these newer
diode sources.  These numbers are using Chroma filter sets, the effort was
spent because we wanted to maximize speed (see our PLOS one paper last
year on imaging danio blood flow).  Essentially the folks at Chroma came
up with a design which only involves two cubes, a dapi/fitc(GFP)/tritc/cy5
cube and a cyan/yellow/red fp cube. So as the exciter filters are part of
the light source we could maximize switching speed for most expts (no cube
change), using triggered acquisition and a sub arrayed CMOS detector this
can be hundreds of multicolor images/second
All powers are measured at the end of the light guide with a Coherent
power meter. The open power is total light coming down the guide with no
filter in place, filtered is self explanatory as is the filter wavelength,
powers are total mW not/unit area.
Hope this helps

 
 
 
 
 
  Nominal wavelength Open Power   filtered Filter Wavelength
 
 
  390nm 220 185 395/25
 
 
  440nm 322 190 440/20
 
 
  475nm 191 147 470/24
 
 
  514nm 91 70 508/24
 
 
  550nm 366 220 550/15
 
 
  575nm 800 230 575/22
 
 
  632nm 265 208 640/30


Simon Watkins Ph.D

Professor and Vice Chair Cell Biology
Professor Immunology
Director Center for Biologic Imaging
University of Pittsburgh
Bsts 225 3550 terrace st
Pittsburgh PA 15261
Www.cbi.pitt.edu <http://Www.cbi.pitt.edu/>
412-352-2277






On 11/5/13, 5:09 PM, "Julio Vazquez" <[hidden email]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>A quick comparison in our lab gave the following:
>
>488 nm (FITC) band of an LED-based light engine (Lumencor): 40 mW
>300 W Xenon Sutter illuminator (probably our brightest light source) with
>FITC EX filter: 70 mW
>
>both measured at the exit of the fiber or light guide.
>
>I agree that LED based light engines are probably at least as good
>(power-wise) as most lamps, plus they have other benefits. Charts such as
>the one found here should be a good guide regarding relative power:
>
>http://lumencor.com/wp-content/uploads/2011/09/SpectraX-LE-User-Manual1.pd
>f
>
>
>Julio Vazquez, PhD
>Fred Hutchinson Cancer Research Center
>Seattle, WA 98109
>
>http://www.fhcrc.org/en.html
>
>
>
>
>On Nov 5, 2013, at 1:50 PM, Kurt Thorn wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> 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:
>>> *****
>>> To join, leave or search the confocal microscopy listserv, go to:
>>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>> *****
>>>
>>> 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:[hidden email]] On Behalf Of Philip Oshel
>>> Sent: Tuesday, November 05, 2013 9:57 AM
>>> To: [hidden email]
>>> Subject: Brightness difference Hg vs LED
>>>
>>> *****
>>> To join, leave or search the confocal microscopy listserv, go to:
>>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>> *****
>>>
>>> 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

[James Pawley]

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Hi all,

Lots of good answers already but I think that it
is important to remember that Hg has a lot of 10x
peaks in the visible part of its spectrum. So an
answer with one bandpass filter may not indicate
a general trend.

One also needs to know a bit about the optics
used. Critical illumination (source focused onto
the image plane) will usually be brighter than
Kohler, but whereas critical illumination that
focuses the brightest "plasma ball" of the arc
into the centre of the imaged area can be
relatively uniform over a small field-of-view, it
is not so clear what will happen when one images
an LED into the image plane (It will depend on
the construction of the LED).

(Note: The actual ball of a 100 w Hg source is
usually about 150µm in diam. just near the
electrode. Assuming both the collector lens and
the objective are of about the same, high NA, the
most efficient optics to convey this to the focus
plane will do so at a magnification of 1:1.  Of
course the field of view of the objective (in µm)
will vary inversely with its magnification, but
the area that can be properly sampled with a
given CCD/sCMOS will not vary: a 1000x1000 array
of 0.1µm pixels will be about 140µm across its
diagonal). However each manufacturer has made
different compromises in terms of the
magnification of their epi-illumination system
(at very least to also accommodate
low-magnification use) and some may utilize more
of the light leaving the original light source
(arc or fibre) than others.

The idea of measuring the output at the
microscope end of a fibre-optic seems sensible as
long as this is how you will illuminate your
sample on your exact setup. However, such fibers
have an NA (angle at which the light leaves them)
and so not all the light leaving them necessarily
makes it to the image plane. For instance, a
given system may under- or overfill the entrance
pupil of a given objective. As one can never make
the light brighter (in photons/second/µm*2)
simply by focusing it, if the end of the fibre is
much larger than 150 µm (in the example above)
then some of the light leaving it  must
inevitably be lost somewhere before it reaches
that part of the focus plane covered by the
1000x1000 image sensor.

My preference would be to measure the light
leaving the objective once the field diaphragm
has been set to repeatable diameter (say 100µm
diam. at the image plane). Of course, you can
only set the diaphragm properly if the scope is
set to Kohler. Once it is set (to standardize the
light path to that point) you can still tweak and
condenser focus to approximate critical
illumination. (i.e., make the image as bright as
possible). The adjustment is inevitably a bit of
a "fudge" because, as the arc is a 3D source
rather than the planar object imagined by the
Kohler Illumination diagram, it "cannot be
focused into a plane".

Of course, there is still a problem: You probably
want to use a hi-NA objective but above NA 0.5
more and more  of the high-NA light will reflect
back into the objective from its front surface.
Rays at >NA 1.0 will not escape into the air at
all. Efforts to couple the sensor of your
photometer to the objective will a drop of
immersion oil will only work if there is no
air-gap between the sensor window and the
sensitive element. The options are:

1) To couple a small, strong plano-convex lens
onto the back of the microscope slide with
immersion oil to make the light beam less
divergent or
2) To set up using an NA 0.75 air objective and
hope that the difference in NA isn't too
important or
3) Measure the fluorescent light signal at the
CCD from a thin, uniform layer of fluorescent dye
(It should be thin so that you don't end up
focusing too far inside the layer, where SA and
absorption may be variables you don't want).

So now you see why just measuring the output of the fibre seems easier.

Hope that this isn't too confusing. I am really
theoretically very pro-LED (faster, cooler, just
the light you want etc). Indeed, I think that
Chapter 3 in the Handbook was one of the first
places where LED microscope sources were
discussed in any depth. I  would just like to see
a few more variables nailed down.

Cheers,

Jim Pawley

>
>
>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:
>>*****
>>To join, leave or search the confocal microscopy listserv, go to:
>>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>*****
>>
>>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/

--
James and Christine Pawley, 5446 Burley Place (PO
Box 2348), Sechelt, BC, Canada, V0N3A0,
Phone [phone], email <[hidden email]>
NEW! NEW! AND DIFFERENT Cell (when I remember to turn it on!) 1-604-989-6146

[Claire Brown]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

We have been testing a number of the solid state light sources. We do a lot
of live cell imaging and they are all way too bright for live cells. We
either add more ND filters so the cells don't die or we turn them way down
in % output if that is an option on the light source. The companies seem to
be making them brighter and brighter. I would love to know what applications
people have that need all this light? We usually advise people to use less
light and longer exposure times even with fixed samples.

That being said we were able to get institutional support to replace our
mercury sources as part of a sustainability program at McGill in a Mercury
Free Microscopy initiative. This will save us lots of time and money in
replacing the mercury bulbs all the time in addition to a reduction in
mercury. Depending on how the sources are used they can also save a lot in
power consumption too.

We have been more interested in stability of the light sources on different
time scales and they really perform well. Variability is in the single
percentage range or less on most time scales. I would be happy to provide
more information to anyone offline if they want to contact me.

Sincerely,

Claire

[Gerard Whoriskey]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Hi Phil and others,

Answering this question can be a bit complex as there is so much variation in
power across the Hg spectrum. There is also some variation across the
LED/solid state hybrid spectrum through it is not so extreme.

In general Hg wins on the sharp peaks but for some time LEDs have won in the
Hg troughs, the main one being between 435nm and 546nm. In most cases
users should now be getting similar results to a new Hg across the spectrum
and more than adequate power for most general wide-field fluorescence work.

If we consider the spectrum split up into 4 bands, violet, blue, green-yellow
and red-NIR we can explain comparisons in a bit more detail. LEDs in the blue
from 440-500nm have been stronger than the Hg for quite some time as in the
red-NIR region. Both these regions are in Hg troughs. The metal halide bulbs
have done a good job filling up the blue trough and its maybe only over the last
couple of years that LEDs are now beating the metal halide in this region. The
violet region which I would put between 365-440nm has been adequate for
some time, most people commenting that DAPI is always too bright. There has
been a lot of progress on power over this region with 365nm now being more
than good enough in most cases. The green-yellow region has been the most
problematic area. Lumencor were the first to deliver good power in this region
and stood out for some time with the phosphor rod technology they use to
cover this region. Other LED technologies have caught up on this now, so
bright green should now be expected from other vendors. At CoolLED we have
seen our green-yellow region improve by as much as 6 times over the past
year.
 
This is all great news however there still can be disappointment from LED
systems and I believe this is down to the limited spectrum. This means that if
filters and LED peaks do not match up then results will be poor. With bulbs
users did not need to be so conscious of filter sets but with LEDs it is crucial.
For example a user may purchase a ‘broad spectrum’ LED/solid state light
source to find that no DAPI is visible as no 365nm is available. In such cases a
new filter set is needed. You may also specify an LED system with 460nm or
470nm that is great for GFP with most cubes. This can fall down however when
a multiband filter set is used which pushes the GFP excitation passband up to
around 490nm. Ideally one would like both the 470nm and 490nm included in
the LED system. Addressing this problem has been a major issue for LED system
manufacturers. Some get around this by offering swappable LED modules but
this brings other issues like swapping time and ensuring combining dichroics are
correct. Just adding more wavelengths is another option but this has a big
overhead with LED systems as each new source requires its own drive
electronics, collimating optics and combining dichroics. Adding more
wavelengths in the conventional way has an increasingly negative impact on
overall power mainly due to the dichroic losses. This has limited the number of
peaks in a system typically to around 4 but up to 6 or 7 at most.

The good news is we have now addressed this limitation with a novel approach
at CoolLED and will be showing our 16 selectable wavelength system, 365-
770nm, at Neuroscience next week.

I’m happy to explain more on this to anyone that is interested.

Kind regards,

Gerry

Technical Manager
CoolLED

[Rosemary.White]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Yes! I agree! These sources are very bright, even the lowest setting is
usually too much for our fluorochromes and can even damage plant cells. We
also had to get ND filters.

And ditto, stability and lifetime are the two key issues, stability more
than anything.

Rosemary White
CSIRO Plant Industry
GPO Box 1600
Canberra, ACT 2601
Australia

T 61 2 6246 5475
F 61 2 6246 5334
M 61 2 420 972 028
E [hidden email]


On 7/11/13 2:40 AM, "Claire Brown" <[hidden email]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>We have been testing a number of the solid state light sources. We do a
>lot
>of live cell imaging and they are all way too bright for live cells. We
>either add more ND filters so the cells don't die or we turn them way down
>in % output if that is an option on the light source. The companies seem
>to
>be making them brighter and brighter. I would love to know what
>applications
>people have that need all this light? We usually advise people to use less
>light and longer exposure times even with fixed samples.
>
>That being said we were able to get institutional support to replace our
>mercury sources as part of a sustainability program at McGill in a Mercury
>Free Microscopy initiative. This will save us lots of time and money in
>replacing the mercury bulbs all the time in addition to a reduction in
>mercury. Depending on how the sources are used they can also save a lot in
>power consumption too.
>
>We have been more interested in stability of the light sources on
>different
>time scales and they really perform well. Variability is in the single
>percentage range or less on most time scales. I would be happy to provide
>more information to anyone offline if they want to contact me.
>
>Sincerely,
>
>Claire

[D Doherty]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Hello to all,

I work for Prior Scientific but this is not meant as  a commercial
response. It is an offer to loan equipment if someone wanted to collect
data with it and share it with this list community.

If someone (should be a non-commercial entity) wanted to spend some time
employing a method of testing as the full illumination system supplied
from the manufacturer along with the recommended filter sets etc. and
not just the particular light source standing on its own, I would be
willing to help by offering to loan our spectral power meter and
software to them. We purpose developed this tool to characterize the
light exiting the objective lens for these very reasons. (The data sheet
for our LumaSpec 800 is online at our website if you want to look at
it.)

This thread has several great comments, information, and suggestions. I
certainly agree that measuring off the scope has meaning, but ultimately
the characterization of brightness (and other factors such as stability)
to eventually choose one illuminator over the other for the person's
application ought to be determined on the microscope tested as a system.
You could have the most powerful, most versatile illuminator on the
planet on the bench right behind your microscope but it might not
perform as you expect. In other words a car with 600 horsepower and
square wheels doesn't get you very far.

Something as simple as the optical coupler / adapter to the microscope
can attribute to light loss and have a huge effect on the final output
exiting your chosen objective lens. There are a host of other things
that can also play a role that have been mentioned by others such as
simple alignment issues, incorrect/misaligned/ unmatched filter sets
etc. so what begins outside the scope eventually changes quite a bit on
its way to your sample for a variety of reasons.  

So if you want to give this a whirl please let me know and drop me an
email. I will also be at Neuroscience next week (and Cell Bio next month
as well) in our booth if you would like to speak to me directly about
this.

Thanks and Regards,

Dennis
 

Dennis Doherty
National Sales Manager
Prior Scientific, Inc.
80 Reservoir Park Drive
Rockland, MA 02370
[hidden email]



-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]]
On Behalf Of [hidden email]
Sent: Wednesday, November 06, 2013 3:00 PM
To: [hidden email]
Subject: Re: Brightness difference Hg vs LED

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Yes! I agree! These sources are very bright, even the lowest setting is
usually too much for our fluorochromes and can even damage plant cells.
We also had to get ND filters.

And ditto, stability and lifetime are the two key issues, stability more
than anything.

Rosemary White
CSIRO Plant Industry
GPO Box 1600
Canberra, ACT 2601
Australia

T 61 2 6246 5475
F 61 2 6246 5334
M 61 2 420 972 028
E [hidden email]


On 7/11/13 2:40 AM, "Claire Brown" <[hidden email]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>We have been testing a number of the solid state light sources. We do a

>lot of live cell imaging and they are all way too bright for live
>cells. We either add more ND filters so the cells don't die or we turn
>them way down in % output if that is an option on the light source. The

>companies seem to be making them brighter and brighter. I would love to

>know what applications people have that need all this light? We usually

>advise people to use less light and longer exposure times even with
>fixed samples.
>
>That being said we were able to get institutional support to replace
>our mercury sources as part of a sustainability program at McGill in a
>Mercury Free Microscopy initiative. This will save us lots of time and
>money in replacing the mercury bulbs all the time in addition to a
>reduction in mercury. Depending on how the sources are used they can
>also save a lot in power consumption too.
>
>We have been more interested in stability of the light sources on
>different time scales and they really perform well. Variability is in
>the single percentage range or less on most time scales. I would be
>happy to provide more information to anyone offline if they want to
>contact me.
>
>Sincerely,
>
>Claire

This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the sender immediately and delete this e-mail. Please note that any views or opinions presented in this email are solely those of the author and do not necessarily represent those of the company.

WARNING: Although the company has taken reasonable precautions to ensure no viruses are present in this email, the company cannot accept responsibility for any loss or damage arising from the use of this email or attachments.

[Benjamin Freiberg]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

All,

Having been involved in the lighting industry from a commercial standpoint I
wanted to respond to this thread in an unbiased and independent experienced
voice.  

As has been previously mentioned, there are many areas of the spectrum in
which solid-state solutions have surpassed HBO in intensity at the sample
plane.  I completely agree with the assessments that there are many
components that go into building an illuminator and therefore many sources
of light loss in the systems on the market.  Key to any measurement of power
is how much light is delivered to the sample, so if anyone does take up the
offer to compare light sources, measurement of mW//cm^2 at the sample plane
will provide the best indication of the total performance of a light source
on a microscope.  That being said, one must make sure that the excitation
filters used with solid-state sources are matched to the peak of the source
and not simply use off the shelf filters and expect them to perform optimally.

There has been mention in this thread of the gaps produced when using
multiple sources and combining them into a shared collimated beam.  As has
been stated, in general, increasing the number of input sources decreases
the overall throughput of light in the system as source combining optics can
be lossy and will cut the overall intensity of any single source that could
be coupled to the microscope.  One solution that has not been mentioned in
this thread is the 120-LED from Lumen Dynamics.  The 120 LED overcomes the
limits of combining multiple sources by using a high intensity white LED
source.  This product, according to the LDGI website, covers wavelengths
from 370nm all the way out to 700+ nm with reasonable intensity.  While HBO
may be brighter at some wavelengths versus the 120-LED, rarely are these
sources, HBO or solid-state, used at max power especially in live cell
applications.

I would suggest that the 120-LED be included in whatever tests come from
this thread as it is a unique product from the standpoint of how the white
light is generated for fluorescence applications versus the other solutions
on the market that combine many sources.

As for the overall performance of all solid state products mentioned thus
far in this thread, one should consider the following: every mid to high end
solid state source produces multiple times more power than 175W xenon at the
sample plane at all wavelengths greater than 360nm and all the way out to
the NIR.  If anyone has experience using xenon as their primary source, I
hope this puts the current state of solid-state illuminator intensity into
perspective.   Bottom line is for most applications, the benefits in cost of
ownership, stability and overall function have the solid-state solutions
greatly out-perform their HBO counterparts with an additional benefit being
that solid-state sources are a green solution and they eliminate the threat
of mercury contamination due to improper disposal or explosion of mercury
burners.

Ben















On Tue, 5 Nov 2013 12:56:42 -0500, Philip Oshel <[hidden email]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>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
>--
>Philip Oshel
>Microscopy Facility Supervisor
>Biology Department
>024C Brooks Hall
>Central Michigan University
>Mt. Pleasant, MI 48859
>[phone]

[Guy Cox-2]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

For once I pretty much totally agree with Jim!  It is just impossible to compare something as peaky as the Hg spectrum with a continuum source.  If one of the Hg peaks matches the excitation you need - Bingo!  Hg is fantastic in the near UV at 360, and even better in the violet at ~405 and ~470.  It is pathetic in the blue (480-500) but brilliant at 550.  Obviously it isn't as specific as a laser source, but you still have to think hard about where your peaks are.  LED sources are much broader, and therefore more versatile.

As for critical illumination - can you actually do it with a commercial epi illuminator?  

                                                                  Guy


Guy Cox, Honorary Associate Professor
School of Medical Sciences

Australian Centre for Microscopy and Microanalysis,
Madsen, F09, University of Sydney, NSW 2006

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of James Pawley
Sent: Thursday, 7 November 2013 1:06 AM
To: [hidden email]
Subject: Re: Brightness difference Hg vs LED

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Hi all,

Lots of good answers already but I think that it is important to remember that Hg has a lot of 10x peaks in the visible part of its spectrum. So an answer with one bandpass filter may not indicate a general trend.

One also needs to know a bit about the optics used. Critical illumination (source focused onto the image plane) will usually be brighter than Kohler, but whereas critical illumination that focuses the brightest "plasma ball" of the arc into the centre of the imaged area can be relatively uniform over a small field-of-view, it is not so clear what will happen when one images an LED into the image plane (It will depend on the construction of the LED).

(Note: The actual ball of a 100 w Hg source is usually about 150µm in diam. just near the electrode. Assuming both the collector lens and the objective are of about the same, high NA, the most efficient optics to convey this to the focus plane will do so at a magnification of 1:1.  Of course the field of view of the objective (in µm) will vary inversely with its magnification, but the area that can be properly sampled with a given CCD/sCMOS will not vary: a 1000x1000 array of 0.1µm pixels will be about 140µm across its diagonal). However each manufacturer has made different compromises in terms of the magnification of their epi-illumination system (at very least to also accommodate low-magnification use) and some may utilize more of the light leaving the original light source (arc or fibre) than others.

The idea of measuring the output at the microscope end of a fibre-optic seems sensible as long as this is how you will illuminate your sample on your exact setup. However, such fibers have an NA (angle at which the light leaves them) and so not all the light leaving them necessarily makes it to the image plane. For instance, a given system may under- or overfill the entrance pupil of a given objective. As one can never make the light brighter (in photons/second/µm*2) simply by focusing it, if the end of the fibre is much larger than 150 µm (in the example above) then some of the light leaving it  must inevitably be lost somewhere before it reaches that part of the focus plane covered by the
1000x1000 image sensor.

My preference would be to measure the light leaving the objective once the field diaphragm has been set to repeatable diameter (say 100µm diam. at the image plane). Of course, you can only set the diaphragm properly if the scope is set to Kohler. Once it is set (to standardize the light path to that point) you can still tweak and condenser focus to approximate critical illumination. (i.e., make the image as bright as possible). The adjustment is inevitably a bit of a "fudge" because, as the arc is a 3D source rather than the planar object imagined by the Kohler Illumination diagram, it "cannot be focused into a plane".

Of course, there is still a problem: You probably want to use a hi-NA objective but above NA 0.5 more and more  of the high-NA light will reflect back into the objective from its front surface.
Rays at >NA 1.0 will not escape into the air at all. Efforts to couple the sensor of your photometer to the objective will a drop of immersion oil will only work if there is no air-gap between the sensor window and the sensitive element. The options are:

1) To couple a small, strong plano-convex lens onto the back of the microscope slide with immersion oil to make the light beam less divergent or
2) To set up using an NA 0.75 air objective and hope that the difference in NA isn't too important or
3) Measure the fluorescent light signal at the CCD from a thin, uniform layer of fluorescent dye (It should be thin so that you don't end up focusing too far inside the layer, where SA and absorption may be variables you don't want).

So now you see why just measuring the output of the fibre seems easier.

Hope that this isn't too confusing. I am really theoretically very pro-LED (faster, cooler, just the light you want etc). Indeed, I think that Chapter 3 in the Handbook was one of the first places where LED microscope sources were discussed in any depth. I  would just like to see a few more variables nailed down.

Cheers,

Jim Pawley

>
>
>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:
>>*****
>>To join, leave or search the confocal microscopy listserv, go to:
>>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>*****
>>
>>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/

--
James and Christine Pawley, 5446 Burley Place (PO Box 2348), Sechelt, BC, Canada, V0N3A0, Phone [phone], email <[hidden email]> NEW! NEW! AND DIFFERENT Cell (when I remember to turn it on!) 1-604-989-6146

[Judy Trogadis-2]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Hi All

This posting of a couple of weeks ago has suddenly become relevant for us.  

Does anyone know of a powerful continuous white light source in the 600-800nm range? Emphasis on the word 'powerful' because in most light sources there seems to be a steep drop in power above 650nm.

Thank you,
Judy

Judy Trogadis
Bio-Imaging Coordinator
Keenan Research Centre, St. Michael's
209 Victoria Street
Toronto M5B 1T8, Canada
office: 416-864-6060 ext. 77612
imaging facility:           ext. 77434
cell:        416-254-9330
[hidden email]



-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Ben Freiberg
Sent: Thursday, November 07, 2013 10:59 PM
To: [hidden email]
Subject: Re: Brightness difference Hg vs LED

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

All,

Having been involved in the lighting industry from a commercial standpoint I
wanted to respond to this thread in an unbiased and independent experienced
voice.  

As has been previously mentioned, there are many areas of the spectrum in
which solid-state solutions have surpassed HBO in intensity at the sample
plane.  I completely agree with the assessments that there are many
components that go into building an illuminator and therefore many sources
of light loss in the systems on the market.  Key to any measurement of power
is how much light is delivered to the sample, so if anyone does take up the
offer to compare light sources, measurement of mW//cm^2 at the sample plane
will provide the best indication of the total performance of a light source
on a microscope.  That being said, one must make sure that the excitation
filters used with solid-state sources are matched to the peak of the source
and not simply use off the shelf filters and expect them to perform optimally.

There has been mention in this thread of the gaps produced when using
multiple sources and combining them into a shared collimated beam.  As has
been stated, in general, increasing the number of input sources decreases
the overall throughput of light in the system as source combining optics can
be lossy and will cut the overall intensity of any single source that could
be coupled to the microscope.  One solution that has not been mentioned in
this thread is the 120-LED from Lumen Dynamics.  The 120 LED overcomes the
limits of combining multiple sources by using a high intensity white LED
source.  This product, according to the LDGI website, covers wavelengths
from 370nm all the way out to 700+ nm with reasonable intensity.  While HBO
may be brighter at some wavelengths versus the 120-LED, rarely are these
sources, HBO or solid-state, used at max power especially in live cell
applications.

I would suggest that the 120-LED be included in whatever tests come from
this thread as it is a unique product from the standpoint of how the white
light is generated for fluorescence applications versus the other solutions
on the market that combine many sources.

As for the overall performance of all solid state products mentioned thus
far in this thread, one should consider the following: every mid to high end
solid state source produces multiple times more power than 175W xenon at the
sample plane at all wavelengths greater than 360nm and all the way out to
the NIR.  If anyone has experience using xenon as their primary source, I
hope this puts the current state of solid-state illuminator intensity into
perspective.   Bottom line is for most applications, the benefits in cost of
ownership, stability and overall function have the solid-state solutions
greatly out-perform their HBO counterparts with an additional benefit being
that solid-state sources are a green solution and they eliminate the threat
of mercury contamination due to improper disposal or explosion of mercury
burners.

Ben















On Tue, 5 Nov 2013 12:56:42 -0500, Philip Oshel <[hidden email]> wrote:

>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>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
>--
>Philip Oshel
>Microscopy Facility Supervisor
>Biology Department
>024C Brooks Hall
>Central Michigan University
>Mt. Pleasant, MI 48859
>[phone]

[Craig Brideau]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

What sort of power are you talking about?  Is a mW per nm 'lots' by the
standards of what you want?

Craig


On Fri, Nov 22, 2013 at 8:33 AM, Judy Trogadis <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi All
>
> This posting of a couple of weeks ago has suddenly become relevant for us.
>
> Does anyone know of a powerful continuous white light source in the
> 600-800nm range? Emphasis on the word 'powerful' because in most light
> sources there seems to be a steep drop in power above 650nm.
>
> Thank you,
> Judy
>
> Judy Trogadis
> Bio-Imaging Coordinator
> Keenan Research Centre, St. Michael's
> 209 Victoria Street
> Toronto M5B 1T8, Canada
> office: 416-864-6060 ext. 77612
> imaging facility:           ext. 77434
> cell:        416-254-9330
> [hidden email]
>
>
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[hidden email]]
> On Behalf Of Ben Freiberg
> Sent: Thursday, November 07, 2013 10:59 PM
> To: [hidden email]
> Subject: Re: Brightness difference Hg vs LED
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> All,
>
> Having been involved in the lighting industry from a commercial standpoint
> I
> wanted to respond to this thread in an unbiased and independent experienced
> voice.
>
> As has been previously mentioned, there are many areas of the spectrum in
> which solid-state solutions have surpassed HBO in intensity at the sample
> plane.  I completely agree with the assessments that there are many
> components that go into building an illuminator and therefore many sources
> of light loss in the systems on the market.  Key to any measurement of
> power
> is how much light is delivered to the sample, so if anyone does take up the
> offer to compare light sources, measurement of mW//cm^2 at the sample plane
> will provide the best indication of the total performance of a light source
> on a microscope.  That being said, one must make sure that the excitation
> filters used with solid-state sources are matched to the peak of the source
> and not simply use off the shelf filters and expect them to perform
> optimally.
>
> There has been mention in this thread of the gaps produced when using
> multiple sources and combining them into a shared collimated beam.  As has
> been stated, in general, increasing the number of input sources decreases
> the overall throughput of light in the system as source combining optics
> can
> be lossy and will cut the overall intensity of any single source that could
> be coupled to the microscope.  One solution that has not been mentioned in
> this thread is the 120-LED from Lumen Dynamics.  The 120 LED overcomes the
> limits of combining multiple sources by using a high intensity white LED
> source.  This product, according to the LDGI website, covers wavelengths
> from 370nm all the way out to 700+ nm with reasonable intensity.  While HBO
> may be brighter at some wavelengths versus the 120-LED, rarely are these
> sources, HBO or solid-state, used at max power especially in live cell
> applications.
>
> I would suggest that the 120-LED be included in whatever tests come from
> this thread as it is a unique product from the standpoint of how the white
> light is generated for fluorescence applications versus the other solutions
> on the market that combine many sources.
>
> As for the overall performance of all solid state products mentioned thus
> far in this thread, one should consider the following: every mid to high
> end
> solid state source produces multiple times more power than 175W xenon at
> the
> sample plane at all wavelengths greater than 360nm and all the way out to
> the NIR.  If anyone has experience using xenon as their primary source, I
> hope this puts the current state of solid-state illuminator intensity into
> perspective.   Bottom line is for most applications, the benefits in cost
> of
> ownership, stability and overall function have the solid-state solutions
> greatly out-perform their HBO counterparts with an additional benefit being
> that solid-state sources are a green solution and they eliminate the threat
> of mercury contamination due to improper disposal or explosion of mercury
> burners.
>
> Ben
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> On Tue, 5 Nov 2013 12:56:42 -0500, Philip Oshel <[hidden email]>
> wrote:
>
> >*****
> >To join, leave or search the confocal microscopy listserv, go to:
> >http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> >*****
> >
> >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
> >--
> >Philip Oshel
> >Microscopy Facility Supervisor
> >Biology Department
> >024C Brooks Hall
> >Central Michigan University
> >Mt. Pleasant, MI 48859
> >[phone]
>

[Kurt Thorn]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

We set up such a system recently using a xenon arc lamp modified for
long-wavelength output from Sutter. At 740 nm we get about 50 mW out of
a 10x objective in a 13 nm bandwidth.  I don't know if that qualifies as
powerful or not, but for epi-fluorescence imaging, it's pretty bright.  
More details on my blog: http://nic.ucsf.edu/blog/?p=813

On a related note, does anyone have some numbers for the power densities
required to saturate common fluorophores? I've been curious about using
LED strobe illumination for very high speed imaging and I'm wondering
how high you can push the power density before you saturate the dyes.

Kurt

On 11/22/2013 7:33 AM, Judy Trogadis wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi All
>
> This posting of a couple of weeks ago has suddenly become relevant for us.
>
> Does anyone know of a powerful continuous white light source in the 600-800nm range? Emphasis on the word 'powerful' because in most light sources there seems to be a steep drop in power above 650nm.
>
> Thank you,
> Judy
>
> Judy Trogadis
> Bio-Imaging Coordinator
> Keenan Research Centre, St. Michael's
> 209 Victoria Street
> Toronto M5B 1T8, Canada
> office: 416-864-6060 ext. 77612
> imaging facility:           ext. 77434
> cell:        416-254-9330
> [hidden email]
>
>
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Ben Freiberg
> Sent: Thursday, November 07, 2013 10:59 PM
> To: [hidden email]
> Subject: Re: Brightness difference Hg vs LED
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> All,
>
> Having been involved in the lighting industry from a commercial standpoint I
> wanted to respond to this thread in an unbiased and independent experienced
> voice.
>
> As has been previously mentioned, there are many areas of the spectrum in
> which solid-state solutions have surpassed HBO in intensity at the sample
> plane.  I completely agree with the assessments that there are many
> components that go into building an illuminator and therefore many sources
> of light loss in the systems on the market.  Key to any measurement of power
> is how much light is delivered to the sample, so if anyone does take up the
> offer to compare light sources, measurement of mW//cm^2 at the sample plane
> will provide the best indication of the total performance of a light source
> on a microscope.  That being said, one must make sure that the excitation
> filters used with solid-state sources are matched to the peak of the source
> and not simply use off the shelf filters and expect them to perform optimally.
>
> There has been mention in this thread of the gaps produced when using
> multiple sources and combining them into a shared collimated beam.  As has
> been stated, in general, increasing the number of input sources decreases
> the overall throughput of light in the system as source combining optics can
> be lossy and will cut the overall intensity of any single source that could
> be coupled to the microscope.  One solution that has not been mentioned in
> this thread is the 120-LED from Lumen Dynamics.  The 120 LED overcomes the
> limits of combining multiple sources by using a high intensity white LED
> source.  This product, according to the LDGI website, covers wavelengths
> from 370nm all the way out to 700+ nm with reasonable intensity.  While HBO
> may be brighter at some wavelengths versus the 120-LED, rarely are these
> sources, HBO or solid-state, used at max power especially in live cell
> applications.
>
> I would suggest that the 120-LED be included in whatever tests come from
> this thread as it is a unique product from the standpoint of how the white
> light is generated for fluorescence applications versus the other solutions
> on the market that combine many sources.
>
> As for the overall performance of all solid state products mentioned thus
> far in this thread, one should consider the following: every mid to high end
> solid state source produces multiple times more power than 175W xenon at the
> sample plane at all wavelengths greater than 360nm and all the way out to
> the NIR.  If anyone has experience using xenon as their primary source, I
> hope this puts the current state of solid-state illuminator intensity into
> perspective.   Bottom line is for most applications, the benefits in cost of
> ownership, stability and overall function have the solid-state solutions
> greatly out-perform their HBO counterparts with an additional benefit being
> that solid-state sources are a green solution and they eliminate the threat
> of mercury contamination due to improper disposal or explosion of mercury
> burners.
>
> Ben
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> On Tue, 5 Nov 2013 12:56:42 -0500, Philip Oshel <[hidden email]> wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> 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
>> --
>> Philip Oshel
>> Microscopy Facility Supervisor
>> Biology Department
>> 024C Brooks Hall
>> Central Michigan University
>> Mt. Pleasant, MI 48859
>> [phone]
>

[Steffen Dietzel]

*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Not quite sure about powerful, but here are my two cents:

For live cell imaging we often use a regular 12V 100W halogen lamp to
avoid the large UV-peaks of the Hg-lamp, which are pretty much
impossible to filter out completely. In the green range, this usually
results in exposure times about 3x as long as with the Hg lamp. Doesn't
bother us since the process we are looking at is slow.

Anyway, the halogen lamp should be more powerful the more you get
towards the infrared, up to well over 800 nm, see e.g.
http://zeiss-campus.magnet.fsu.edu/articles/lightsources/tungstenhalogen.html
So you might want to give it a try. The other day I used a red DNA stain
(Cy5-Channel), 40x air objective, with the lamp only on 6V and the
signal was still pretty bright. So maybe that would do for your purpose?
Since you probably have all the parts already, you might want to give it
a try.

Steffen




On 22.11.2013 16:33, Judy Trogadis wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi All
>
> This posting of a couple of weeks ago has suddenly become relevant for us.
>
> Does anyone know of a powerful continuous white light source in the 600-800nm range? Emphasis on the word 'powerful' because in most light sources there seems to be a steep drop in power above 650nm.
>
> Thank you,
> Judy
>
> Judy Trogadis
> Bio-Imaging Coordinator
> Keenan Research Centre, St. Michael's
> 209 Victoria Street
> Toronto M5B 1T8, Canada
> office: 416-864-6060 ext. 77612
> imaging facility:           ext. 77434
> cell:        416-254-9330
> [hidden email]
>
>

--
------------------------------------------------------------
Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Walter-Brendel-Zentrum für experimentelle Medizin (WBex)
Head of light microscopy

Mail room:
Marchioninistr. 15, D-81377 München

Building location:
Marchioninistr. 27,  München-Großhadern