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LEDs

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Ippei Kotera

Re: LEDs

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Hi Julio,

You need to use surface power density (W/m^2) if you want to know which
illumination system bleaches chromophores faster. Total power at the
focal plane cannot be used for photobleaching comparison unless the
illumination area is held constant.

> Incidentally, I originally performed the comparison between microscopes because some of our users think lasers are used on microscopes because they have more power than mercury lamp (or similar) illumination, and also that a laser based microscope will bleach the sample more than one with a lamp. I was trying to show that this is not true. In fact, we could easily get 10-20 mW at the focal plane with lamps and filters for most excitation bands on most of our microscopes, which is more than the nominal power of any laser line on our confocal (some of which are no stronger than a laser pointer), and definitely much more than the actual power we would use for imaging.

Ippei

--
Ippei Kotera, PhD

Centre for Research in Neurodegenerative Diseases
Tanz Neuroscience Building, Room 221
University of Toronto
6 Queen's Park Crescent West
Toronto, Ontario M5S 3H2

Phone: (416)978-2503
Fax: (416)978-1878

Craig Brideau

Re: LEDs

In reply to this post by Guy Cox-2

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Yeah, the part where it sort-of has a bulb threw me for a loop. So it
seems like it is a bulb without filaments; just a gas pocket inside a
dielectric. It will be interesting to learn what the 'field' lifetime of
the bulbs actually end up being.

Craig

On Sun, Feb 26, 2012 at 6:30 PM, Guy Cox <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> If you follow the links from that Thorlab website you gave, you find:
>
> "the heart of LIFI(r) is the bulb sub-assembly where a sealed bulb is
> embedded in a dielectric material. This design is more reliable than
> conventional light sources that insert degradable electrodes into the bulb.
> The dielectric material serves two purposes: first as a waveguide for the
> RF energy transmitted by the RF Power Amplifier Circuit (PA) and second as
> an electric field concentrator that focuses energy in the bulb. The energy
> from the electric field rapidly heats the material in the bulb to a plasma
> state that emits light of high intensity and full spectrum."
>
> In other words, it's not solid-state at all. But it's a very neat idea.
> Note that they don't tell you what's in the bulb!
>
>
> Guy
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[hidden email]]
> On Behalf Of Craig Brideau
> Sent: Monday, 27 February 2012 12:11 PM
> To: [hidden email]
> Subject: Re: LEDs
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Some of these 'solid state' light sources claim to be plasma based? What
> are these things, and does anyone care to share their experiences with
> them? Here's a link to the kind of source I'm talking about:
>
> http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=5551
>
> I don't have any experience with these and was curious.
>
> Craig
>
>
> On Sun, Feb 26, 2012 at 10:38 AM, Christian Mohn <
> [hidden email]
> > wrote:
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > *****
> >
> > Hi,
> >
> > we are just about to go thru the same procedure. Some things became
> > obvious while unravelling the marketing pdfs.
> > 1. nobody tells you where and how they measure output or what the
> > illuminated field of view is... 45mW on a 11mm f.o.v is different from
> > 45 mW on a 25mm field of view (I assume the direct coupled will all
> > fill the 25 while a 0.3NA fibre only fills F.oV of 16mm reasonably) 2.
> > solid-state is just another word for "yes, for some we use a phosphor
> > in front the led chip" and this will definatly not increase overall
> > power since phosphorescence will never reach 100% efficiency....
> >
> > My advice... get a device to your lab and test it.
> >
> > Best wishes from the cold north,
> >
> > Chris
> >
>

Julio Vazquez

Re: LEDs

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And with regard to Lumencor and similar light engines, a description of the system can be found here:

http://www.lumencor.com/docs/Lumencor%20White%20Paper.pdf

and more detailed information of what's inside can be found in Lumencor's various patents, such as this one:

http://www.patentgenius.com/patent/8098375.html

Julio.

==

----- Original Message -----
From: "Craig Brideau" <[hidden email]>
To: [hidden email]
Sent: Monday, February 27, 2012 4:14:08 PM
Subject: Re: LEDs

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

Yeah, the part where it sort-of has a bulb threw me for a loop. So it
seems like it is a bulb without filaments; just a gas pocket inside a
dielectric. It will be interesting to learn what the 'field' lifetime of
the bulbs actually end up being.

Craig

On Sun, Feb 26, 2012 at 6:30 PM, Guy Cox <[hidden email]> wrote:

Gerard Whoriskey

Re: LEDs

Commercial Response

We have followed this discussion thread with interest. We can confirm that CoolLED provides spectral data on its website and we endeavour to respond quickly when more detailed information is requested.

Excitation filters are required as LEDs do emit a significant tail off the peak that would show up as background when it crosses the emission filter passband. The level of blocking required when using LEDs is much less than when using an Hg bulb so there is no need for an OD=6 outside of the excitation passband. This should reduce the demands on filtering as LEDs become more common in fluorescence.

We fully understand the complexities involved when measuring intensity at the sample. I have personally been shocked at how much results can vary depending on the measuring kit, microscope set-up and techniques used. This may explain why some product manufacturers claim extreme intensity results that don’t hold up when side-by-side comparisons are made. CoolLED can provide product on evaluation so that the user can be satisfied that performance will be achieved in their application.

CoolLED would also be happy to provide its LED product to any impartial individual or institution interested in doing a comparison of sources. We are happy to share our knowledge on measuring intensity based on many years of experience in LED illumination in microscopy.

Best Regards,

Gerry

Gerard Whoriskey

Development Engineer

Email: [hidden email]
Tel: +44 (0)1264 323040
Fax: +44 (0)1264 723897
Mobile: +44 (0)7789535762

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Vazquez Lopez, Julio
Sent: 28 February 2012 01:01
To: [hidden email]
Subject: Re: LEDs

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

And with regard to Lumencor and similar light engines, a description of the system can be found here:

http://www.lumencor.com/docs/Lumencor%20White%20Paper.pdf

and more detailed information of what's inside can be found in Lumencor's various patents, such as this one:

http://www.patentgenius.com/patent/8098375.html

Julio.

==

----- Original Message -----
From: "Craig Brideau" <[hidden email]>
To: [hidden email]
Sent: Monday, February 27, 2012 4:14:08 PM
Subject: Re: LEDs

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

Yeah, the part where it sort-of has a bulb threw me for a loop. So it seems like it is a bulb without filaments; just a gas pocket inside a dielectric. It will be interesting to learn what the 'field' lifetime of the bulbs actually end up being.

Craig

On Sun, Feb 26, 2012 at 6:30 PM, Guy Cox <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> If you follow the links from that Thorlab website you gave, you find:
>
> "the heart of LIFI(r) is the bulb sub-assembly where a sealed bulb is
> embedded in a dielectric material. This design is more reliable than
> conventional light sources that insert degradable electrodes into the bulb.
> The dielectric material serves two purposes: first as a waveguide for
> the RF energy transmitted by the RF Power Amplifier Circuit (PA) and
> second as an electric field concentrator that focuses energy in the
> bulb. The energy from the electric field rapidly heats the material in
> the bulb to a plasma state that emits light of high intensity and full spectrum."
>
> In other words, it's not solid-state at all. But it's a very neat idea.
> Note that they don't tell you what's in the bulb!
>
>
> Guy
>
> -----Original Message-----
> From: Confocal Microscopy List
> [mailto:[hidden email]]
> On Behalf Of Craig Brideau
> Sent: Monday, 27 February 2012 12:11 PM
> To: [hidden email]
> Subject: Re: LEDs
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Some of these 'solid state' light sources claim to be plasma based?
> What are these things, and does anyone care to share their experiences
> with them? Here's a link to the kind of source I'm talking about:
>
> http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=5551
>
> I don't have any experience with these and was curious.
>
> Craig
>
>
> On Sun, Feb 26, 2012 at 10:38 AM, Christian Mohn <
> [hidden email]
> > wrote:
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > *****
> >
> > Hi,
> >
> > we are just about to go thru the same procedure. Some things became
> > obvious while unravelling the marketing pdfs.
> > 1. nobody tells you where and how they measure output or what the
> > illuminated field of view is... 45mW on a 11mm f.o.v is different
> > from
> > 45 mW on a 25mm field of view (I assume the direct coupled will all
> > fill the 25 while a 0.3NA fibre only fills F.oV of 16mm reasonably) 2.
> > solid-state is just another word for "yes, for some we use a
> > phosphor in front the led chip" and this will definatly not increase
> > overall power since phosphorescence will never reach 100% efficiency....
> >
> > My advice... get a device to your lab and test it.
> >
> > Best wishes from the cold north,
> >
> > Chris
> >
>

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