[Histonet] mercury vs led lights

[Morken, Tim]

Necat, 

The advantages of LED's are:

1) The wavelength is pure in the spectrum the LED is designed for while mercury are quite variable across their spectrum. 

2) LED's last many thousands of hours - in the range of 20,000 to 50,000 hours for most uses. This alone will lead to major expense reduction since mercury lamps, at $200 each, last a few hundred hours at best. Even 400 to 1200 hours for xenon lamps will be very expensive compared to LED's). In fact, depending on the level of microscope you get you may be able to pay for a microscope over it's lifetime just in lamp replacement savings.

3)LED's do not require any warmup or cooldown time and can switched on and off at will 

4) You can use a dimmer control on LED's without affecting the spectrum.

4) Because of #2 and #3 LED's are very robust, easy to use and do not require any special care, unlike mercury and xenon lamps that require special training and handling to use correctly. LED's are perfect for student microscopes.

In the past the major disadvantage of LED's was that they were not very intense/powerful (1W or so, equivalent to a 50W mercury burner) and could not be used in epi-fluroescence without losing most of their intensity as the light passes through all the glass lenses. Now much more powerful LED's are available (up to 5W) that are suitable for epi. 

Disadvantages:

1) You do need a specific LED lamp for each wavelength range you want to use. One LED will not cover the whole spectrum. 

2) The microscope must be designed to use an LED lamp. However, there are adaptors available for some microscope models (see http://www.fraensrl.com/flmicro.html ), but only for bright field transmission mode.


References:


Light sources
http://micro.magnet.fsu.edu/primer/anatomy/lightsourceshome.html

Also
http://micro.magnet.fsu.edu/primer/techniques/fluorescence/fluorosources.html


LED's
http://zeiss-campus.magnet.fsu.edu/articles/lightsources/leds.html

LED's



Tim Morken
UCSF Medical Center
San Francisco, CA  
 

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Nejat Yilmaz
Sent: Wednesday, September 09, 2009 6:58 AM
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] mercury vs led lights

Dear Colleagues,

We're attempted to buy a new inverted fluorescence microscope for our 
research lab. Distrubitor of leica offered us a new type system working with 
led lights which is about same price. Does anybody know advantages and 
disadvantages of this system compared to conventional (with mercury lamp) 
fluorescence microscopes.
Thanks in advance.

Necat Yilmaz 


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