LEDs

[Richard Cole]

LEDs offer many advantages over traditional sources such as mercury arc lamp.

 

Most notably, they provide brightness and spectral control.  For fluorescent imaging, LEDs offer advantages of providing longer lifespan, higher spatial and temporal stability, eliminate the need for mechanical shutters, neutral density filters, significantly lower cost of ownership and reduce photon dose at the specimen. Additionally, LEDs allow for vibration free high speed spectral and temporal modulation. 

 

There are many commercial vendors:

 

The Colibri illumination system (Zeiss Optics Inc. Thornwood, NY 10594) offers up to ten different LEDs that can be switched on and off and be adjusted in the microsecond range solely based on optoelectronics. 

 

There are many aftermarket sources for LED based illumination systems.  An example of complete illumination system is the CoolLED system (CoolLED,  Andover, UK) with up to 18 different LED wavelengths to match excitation peaks of fluorophores available in manual or automatic control modes.  There are many modular LED based illumination systems available; the Prizmatix (Prizmatix Ltd., Southfield, MI 48075) is one example, comprised of up to three high power LED modules and corresponding dichroic beam splitters.  Modulated LED Source, such as model DC3100, applicable for live cell imaging or fluorescence lifetime imaging (FLIM) microscopy is available from Thor Labs (Newton, New Jersey 07860) and adaptable for most microscope stands.  

 

 

There are even more component level sources

 

Regards,

 

Rich

 

 

I have no commercial interest in any of the aforementioned companies

 

 

Richard Cole
Research Scientist IV
Director: Advanced Light Microscopy Core Unit
Wadsworth Center

 

Research Assistant Professor
Dept. of Biomedical Sciences
School of Public Health State University of New York

P.O. Box 509 Albany N.Y. 12201-0509
518-474-7048 Phone
518-474-4430 Fax

 

Email [hidden email]

Website www.wadsworth.org/cores/alm/index.htm

 

 

---

From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of CONFOCALMICROSCOPY automatic digest system
Sent: Monday, January 11, 2010 1:04 AM
To: [hidden email]
Subject: CONFOCALMICROSCOPY Digest - 8 Jan 2010 to 10 Jan 2010 (#2010-4)

 

 

CONFOCALMICROSCOPY Digest - 8 Jan 2010 to 10 Jan 2010 (#2010-4)

Table of contents:

• LEDs (3)

1. LEDs
• <a href="cid:[e-mail]">LEDs (01/10)
  From: Dirk Landgraf <[hidden email]>
• <a href="cid:[e-mail]">Re: LEDs (01/10)
  From: James Pawley <[hidden email]>
• <a href="cid:[e-mail]">Re: LEDs (01/10)
  From: Craig Brideau <[hidden email]>

 

Browse the CONFOCALMICROSCOPY online archives.

 

IMPORTANT NOTICE: This e-mail and any attachments may contain
confidential or sensitive information which is, or may be, legally
privileged or otherwise protected by law from further disclosure. It
is intended only for the addressee. If you received this in error or
from someone who was not authorized to send it to you, please do not
distribute, copy or use it or any attachments. Please notify the
sender immediately by reply e-mail and delete this from your
system. Thank you for your cooperation.

[Zucker.Robert]

Rich
what is the status of confocal QA paper
bob


Robert M. Zucker, PhD
U.S. Environmental Protection Agency
Office of Research and Development
National Health and Environmental Effects Research Laboratory.
Toxicology
Assessment Division
Telephone: [phone]   Fax: [phone]
e-mail: [hidden email]

Mail address: USEPA,ORD,NHEERL,TAD
Developmental Biology Branch ( MD 67)
Research Triangle Park, North Carolina, 27711

Shipping address:
2525 E.NC Highway 54
Durham, NC, 27713

[Caroline Bass]

Since we are on the topic, are there any easy and relatively easy way to adapt a stereomicroscope with LEDs? I’d like a dissecting microscope to visualize GFP.

Thanks!

Caroline

[Craig Brideau]

What style of microscope specifically?  Do you have a particular
make/brand in mind?  Basically you just need to find an optical or
physical path to get the light from the LEDs to the sample.

Craig


On Tue, Jan 12, 2010 at 12:31 AM, Caroline Bass <[hidden email]> wrote:
> Since we are on the topic, are there any easy and relatively easy way to
> adapt a stereomicroscope with LEDs? I’d like a dissecting microscope to
> visualize GFP.
>
> Thanks!
>
> Caroline

[Caroline Bass]

I don't have a specific brand in mind, just inexpensive. I need something
that will allow me to visualize but with enough working distance to dissect
the sample. Hopefully powerful enough to visualize GFP in rat brain sections
- I usually get a very good signal. I would welcome any suggestions on how
to make this GFP "cheapostereoscope" from off-the-shelf parts.

Caroline


On 1/12/10 2:47 AM, "Craig Brideau" <[hidden email]> wrote:

> What style of microscope specifically?  Do you have a particular
> make/brand in mind?  Basically you just need to find an optical or
> physical path to get the light from the LEDs to the sample.
>
> Craig
>
>
> On Tue, Jan 12, 2010 at 12:31 AM, Caroline Bass <[hidden email]> wrote:
>> Since we are on the topic, are there any easy and relatively easy way to
>> adapt a stereomicroscope with LEDs? I¹d like a dissecting microscope to
>> visualize GFP.
>>
>> Thanks!
>>
>> Caroline

[Emmanuel Gustin]

Hi,

 

I agree with Rich’s list of advantages, but of course there are also some limitations to take into account, at least in my limited experience.

 

Directly coupled LEDs don’t have the same illumination homogeneity as the latest generation of liquid light guide-coupled lamps. If you don’t adjust the condensor lens correctly, you can see the structure of the LED in your image. Of course you also have that problem with a directly attached lamp, and I guess it would be eliminated by using a light guide with a LEDs.

 

LEDS are not strictly monochromatic but have emission bands composed of a set of transitions. When I was a student, one exercise we were asked to do was to dip LEDs in liquid nitrogen, to get narrower bands, and analyze their spectra and to figure out what semiconductors and doping had been used in their construction... Unlike when you use a semiconductor laser, you may still need to use excitation filters with a LED.

 

best regards,

 

Emmanuel

 

[Peter Gabriel Pitrone]

Hey Caroline,

you could always try this with a high quality green camera filter and  
a blue led underneath:
http://www.funsci.com/fun3_en/uzoom/uzoom.htm  ;0)

Pete




On Jan 12, 2010, at 9:19 AM, Caroline Bass wrote:

I don't have a specific brand in mind, just inexpensive. I need  
something
that will allow me to visualize but with enough working distance to  
dissect
the sample. Hopefully powerful enough to visualize GFP in rat brain  
sections
- I usually get a very good signal. I would welcome any suggestions  
on how
to make this GFP "cheapostereoscope" from off-the-shelf parts.

Caroline


On 1/12/10 2:47 AM, "Craig Brideau" <[hidden email]> wrote:

> What style of microscope specifically?  Do you have a particular
> make/brand in mind?  Basically you just need to find an optical or
> physical path to get the light from the LEDs to the sample.
>
> Craig
>
>
> On Tue, Jan 12, 2010 at 12:31 AM, Caroline Bass <[hidden email]>  
> wrote:
>> Since we are on the topic, are there any easy and relatively easy  
>> way to
>> adapt a stereomicroscope with LEDs? I’d like a dissecting  
>> microscope to
>> visualize GFP.
>>
>> Thanks!
>>
>> Caroline

[Dale Callaham]

Hi Caroline,

I just have some ideas. The 2 sources I will give you for UV-LEDs are
surplus sources so their stock changes, but the parts they show today
are cheap enough that you can experiment with it. These links may wrap
so copy and paste the full URL into your browser...

http://www.allelectronics.com/make-a-store/category/340075/LEDs/5mm-Ultraviolet/1.html

http://www.goldmine-elec-products.com/products.asp?dept=1239

I would stick to 20mA current (control it, see below) unless you know
other specs. These devices will have a nominal operation current and an
"absolute max" dc current at which point you risk toasting the small
wires inside the device. Buy some visible high output LEDs to experiment
with.... and remember that the UV from these can damage your eye same as
from any other UV source.

LEDs can have different emission patterns and to avoid optics in
addition to the LED you want to find one with a 15 to 30 degree pattern
from the molded LED lens. The one from All Electronics specifies, the
other doesn't.  Buying prime LEDs from a regular distributor will always
give you more specs, possibly reliability and consistency, but will cost
more.

A couple of points. LEDs are listed with a Forward Voltage at a
particular forward current : something like Vf = 3.6V @ 20mA (just an
example!). The Forward voltage is NOT something you control - it is a
function of the chip construction/composition; you want either provide a
regulated current (from a "current source" or current regulated power
supply, or ASSUME that Vf value in your circuit and calculate
appropriate resistance in the circuit so that the applied voltage will
deliver that current and no more.

LEDs can be wired in series, adding up all the Vf voltages and choosing
a power supply that will allow for current control or addition of a
current stabilizing "ballast resistor" in series with the LEDs.

If you get into higher power devices there are some interesting devices
that seems like it might be useful to homebrew construction:
The BuckPuck is a simple controller that allows for dimming (output
current control...):
http://ledsupply.com/led-drivers.php
http://www.leddynamics.com/LuxDrive/datasheets/3021-BuckPuck.pdf

I have no connection with these companies.

Dale Callaham

Caroline Bass wrote:
>   Since we are on the topic, are there any easy and relatively easy way
> to adapt a stereomicroscope with LEDs? I’d like a dissecting microscope
> to visualize GFP.
>
> Thanks!
>
> Caroline

[Dale Callaham]

Caroline,

In my previous post I mentioned UV leds and you will be looking for Blue
leds. Sorry. LED Supply, Inc also has a range of emission wavelengths so
you can choose - they do have some at 470nm and 15/30/45 degree patterns.
http://ledsupply.com/5mm-leds.php

  I have found that the illumination from leds can be structured, and
find that passing it through one layer of a translucent (the hazy white
ones..) shopping bag plastic does a nice job of scrambling the structure
of the emission pattern without much attenuation.

Dale


Caroline Bass wrote:
>   Since we are on the topic, are there any easy and relatively easy way
> to adapt a stereomicroscope with LEDs? I’d like a dissecting microscope
> to visualize GFP.
>
> Thanks!
>
> Caroline

[Konz, Richard]

Hi Bob:

Please remind me about the details.

Many thanks,

-Rich


-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]]
On Behalf Of [hidden email]
Sent: Monday, January 11, 2010 4:15 PM
To: [hidden email]
Subject: Re: Confocal QA

Rich
what is the status of confocal QA paper
bob


Robert M. Zucker, PhD
U.S. Environmental Protection Agency
Office of Research and Development
National Health and Environmental Effects Research Laboratory.
Toxicology
Assessment Division
Telephone: [phone]   Fax: [phone]
e-mail: [hidden email]

Mail address: USEPA,ORD,NHEERL,TAD
Developmental Biology Branch ( MD 67)
Research Triangle Park, North Carolina, 27711

Shipping address:
2525 E.NC Highway 54
Durham, NC, 27713

[Craig Brideau]

>  I have found that the illumination from leds can be structured, and find
> that passing it through one layer of a translucent (the hazy white ones..)
> shopping bag plastic does a nice job of scrambling the structure of the
> emission pattern without much attenuation.
>
> Dale

I used a cheap ground glass diffuser, but as you say, any white hazy
material will work.  You will take a hit in power doing this, but it
is worth it to even-out the illumination.  Just buy sufficiently
powerful LEDs to compensate for the loss.

Craig