[Histonet] Re: Histonet Digest, Vol 70, Issue 11

Eric Hoy Eric.Hoy <@t> UTSouthwestern.edu
Wed Sep 9 21:03:25 CDT 2009

Regarding the LED light sources for fluorescent microscopy, we have been
using one of these for the past six months, and it is wonderful.  The
lighting is bright, even, and it doesn't quench (photobleach) FITC as fast
as mercury lamps do.  It is easy to align, and the expected life of the LEDs
is at least 10,000 hours.

I used mercury lamps for many years, and they were fun for those of us who
like to tinker with instruments, but overall, they are a pain in the neck to
use every day.  About two years ago, we bought a new Nikon 50i microscope,
which is one of the best clinical microscopes I have ever used.
Unfortunately, the Nikon rep talked us into the EXFO metal halide light
source.  This looked good in the demo, but it has spent more time being
repaired than working in our lab.  Right now it is back at Nikon while they
try to figure out what is wrong with it.

The LED light source that we are currently using is from a company called
Fraen.  They are an Italian company, but they have an office in the US.  The
unit is small, easy to install, easy to align, and gives illumination
equivalent to a 100 watt mercury lamp.

Merced said that there are no LEDs available for red wavelengths, but this
must just be true for Zeiss.  Fraen has LED modules that cover virtually all
of the fluorochromes that I have ever heard of.  They have one for red
wavelengths that will work with TRITC, Cy3, Texas Red, Alexa Fluor 633,
Alexa Fluor 647, and even Cy5, which has maximum excitation at about 650 nm,
well into the red range.

You do need to have different LEDs for various fluorochromes, but Fraen has
7 modules available, and for practical terms, about 4 of them would cover
everything from DAPI to Cy5.  They are easy to interchange on the Fraen

I don't work for any of the companies mentioned here, nor do I receive any
compensation for saying nice things about their products.  I just like their

Eric Hoy

Eric S. Hoy, Ph.D., SI(ASCP)
Clinical Associate Professor
Department of Medical Laboratory Sciences
The University of Texas Southwestern Medical Center
Dallas, Texas
Email: Eric.Hoy <@t> UTSouthwestern.edu

> Message: 1
> Date: Wed, 09 Sep 2009 13:43:45 -0400
> From: Merced M Leiker <leiker <@t> buffalo.edu>
> Subject: Re: [Histonet] mercury vs led lights
> To: Nejat Yilmaz <nyilmaz <@t> mersin.edu.tr>,
> histonet <@t> lists.utsouthwestern.edu
> Message-ID: <6276F2A000238523BC2681F5 <@t> CDYwxp1931.ad.med.buffalo.edu>
> Content-Type: text/plain; charset=us-ascii; format=flowed
> I forgot to mention. An LED can be made to excite FITC, DAPI, and Cy5
> (far-red) fluorophores, but they cannot make them in the red (Alexa Fluor
> 555, Cy3, TRITC, etc.) This is per our Zeiss rep. So on our inverted
> microscope we have LEDs and we also have a mercury lamp to cover the red
> range. The Zeiss switches nicely and very smoothly between the light
> sources during viewing and image acquisition.
> Sorry for the highly untechnical description, but that is all I know about
> it.  :-)

More information about the Histonet mailing list