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re the informative posting on LEDs by Barbara Foster
catalogue prices for LEDs seem to be very low, so how come
Cost of LED cassette: Eu720 ?
which seems to be a couple of orders of magnitude greater.
In addition you would need to purchase several LEDs
Jeremy Adler
Cell Biology
The Wenner-Gren Inst.
Arrhenius Laboratories E5
Stockholm University
Stockholm 106 91
Sweden
-----Original Message-----
From: Confocal Microscopy List on behalf of Barbara Foster
Sent: Tue 06/11/2007 17:27
To: [log in to unmask]
Subject: Re: Non-arc source for IX-81 - semi commercial
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Dear Glen
As a strategic consultant in microscopy, I get to see the latest
technology and there is, indeed, a great deal of flurry about LED
technology. In the summer of 2006, I had a chance to evaluate the
AFTER/FluoLED from Fraen and was very impressed with the design, ease
of use, and flexibility. I have been working on assignment with
Fraen more recently and was surprised to see how much both LED
technology and this product line had evolved. So here are
observations on both LED technology in general, and the Fraen system
in particular.
Fraen's FluoLEDs are now available in UV (354nm), Royal blue (450nm),
Blue (480nm), Cyan (505 nm), Green (535nm) Yellow (590nm) and red
(630nm). While Fraen is a new name in the microscopy arena, most of
you already know them: they are the world's largest manufacturer of
the LEDs used for the pointers/indicators for the speedometers, gas
gauges, etc., on the dashboard of your cars.
Until recently Fraen's AFTER/FluoLEDs were only available in
transmitted light version for upright microscopes, currently, over 17
different models from all the major manufacturers and several of the
smaller ones. For us "old timers", transmitted light has typically
been seen as less efficient, but the superb images from FluoLED tell
a very different story: Bright features against wonderfully velvet
black background. In other words: great S/N. Fraen will be
releasing the first systems for inverted stands next month and have
begun work on an epi version as well.
As with any technology, there is up side/down side to LEDs
The good news is the consistency, lack of fuss, and economy of
LEDs. When they are on, they are on. When they are off and you need
them on, you can turn them on immediately - no cycle time.
Also, they exhibit much less drop off over time than HBOs. That time
factor is critical. Life expectancy of an HBO is on the order of
200-300 hrs; for Fraen's LED's (I don't have figures on the others)
30,000 hrs. No error in decimal points here: you can run them 8 hrs
a day, 5 days a week, for 5 years without changing a lamp. If you
plot drop-off versus time, a 100 fold increase in time is
significant, especially for those of us doing long term experiments.
When it comes time to switch out the lamp, there is no alignment, no
disposal issue.
The economy issue is also an interesting. Fraen's European office
did the following calculations (Euros) for the LED cassette for a
standard Blue excitation kit vs. an HBO arc lamp:
Cost of LED cassette: Eu720 Cost of HBO lamp: 160
Lifetime LED casette: 30,000hrs Lifetime HBO lamp: 300 hrs
Eu/hr LED cassette: EU 0.024 Eu/hr HBO lamp: Eu 0.53
Assumption: if you run both systems for 2000 hrs/year
Cost of LED cassette/yr: Eu48 Cost of HBOs/year: Eu1060.
Savings, using LEDs: Eu1012
One more bit of good news: LEDs are also a much cooler source so
there is dramatically less photobleaching.
The down side really isn't very down, just something to be aware of.
Because of the state of LED technology, green and yellow LEDs
generate less power so the resulting images will be somewhat less
bright than with HBO. This is not much of an issue when the
fluorescence is viewed at magnifications up to about 60x but if you
routinely use 100x objectives, you should run the test to see if it
is a problem with your particular samples. The good news is (a) for
green LEDs, research is powering ahead. Fraen expects to have new,
brighter LEDs in Feb 08. (b) For Yellow (Texas red, etc.), research
is slower. However, they also have a good news side: they exhibit
better S/N ratio, even at the lower power, than HBO.
The FluoLED family has a number of things to recommend it:
a. They have engineered a clever "multi-cube" device so that you can
have 1 LED, 2 LEDs, or 3 LEDs and can switch conveniently from one to another
b. For multi-user labs, the LED cassettes can be switched quickly and
easily. This feature reminded me of the old Reichert Polyvars, one
of my favorite microscopes, especially for teaching. The
fluorescence (and reflected light DIC and Darkfield) cubes came on
"lolly pop" sticks so that you could just slide in what you
needed. FluoLED has mimicked that flexibility with their cassette
approach. A lab can have a set of cassettes sitting in a drawer next
to the microscope or each group can have what they need in their own
area, so they can have whatever excitation/emission they need by just
plugging in their cassette and tightening the locking
screw. Immediate change out... no alignment!
c. Fraen has engineered intelligent electronics into their
controllers. Different wavelength LEDs require different amperages
to drive them. With Fraen's system, when a cassette is plugged into
position, the controller intelligently senses which LED is in the
cassette and provides the appropriate amperage, even with the 3
cassette system.
d. The controller also allows the user to change intensity so that
you can balance different channels for optimum imaging.
e. Finally, and as a past high school teacher, I loved this one...
Fraen has engineered less expensive "baby" systems in Blue and Royal
blue, so that we can finally get fluorescence into teaching labs.
That's the story. I hope it was helpful. I am at Neuroscience this
week and LEDs are, indeed,grabbing a lot of interest.
Best regards,
Barbara Foster, President
We've moved!
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At 07:21 AM 11/6/2007, Gerard Whoriskey wrote:
>Search the CONFOCAL archive at
>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
>Hi Glen,
>The argument for LED systems is very strong on reliability and operational
>costs and is continually improving with regard to performance, measured in
>choice of wavelengths and intensity.
>I assume that in your confocal set-up you are only using the mercury based
>bulb system to check and align samples and that you only need excitation
>regions that match the laser lines you are using. An LED system that you
>can switch on and off as you please is ideal for such applications and a
>very cost effective replacement to bulbs.
>Commercial bit:
>We have only recently included 445nm and 505nm options to our range. Now
>users can choose from 7 options of 400nm, 445nm, 465nm, 505nm, 525nm,
>595nm, and 635nm.
>I will contact you directly with more commercial information.
>
>Best Regards,
>
>Gerry
>
>Gerard Whoriskey
>Development Engineer
>CoolLED Ltd
>CIL House
>Charlton Road
>Andover
>Hampshire
>SP10 3JL
>
>Mob: 07789535762
>Tel: +44 (0) 1264 321321
>Dir: +44 (0)1264 320984
>web site: www.coolled.com
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