Guidance wanted on illumination stability

[Gordon Scott]

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Hi Guys,

I'm looking at ways to further improve the performance and efficiency of
our light sources.

There are always tradeoffs when doing this and I'd like to better
understand what tradeoffs are acceptable for real microscopy users.

Our present illumination sources all use a switched-mode pre-regulation
and a linear final regulation for the LED power, so ripple is very low,
but at a cost for us of some power wasted in the linear stages.

I can improve that efficiency and reduce the waste by foregoing the
linear stage and regulating directly with the switching mode, but the
tradeoffs are a longer On/Off switching time than is feasible with
linear, and a high-frequency ripple.

My simulations suggest switch-on and switch-off times of around 50us and
a ripple of around 25% at 100kHz, which would be reasonable from an
electrical/energy point of view.



The question is, of course, would any of the people likely to use it
find that performance difficult or unacceptable?



I've copied to the list rather than posting direct, so hopefully the
replies will come to me rather than cluttering the list.

Thanks for considering the question, even if you need not, or choose
not, to answer.

Kind regards,
                 Gordon.
 --
 Gordon Scott  Design Engineering
            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
            CoolLED                    http://www.coolled.com
            CoolLED is a division of Custom Interconnect Ltd.
            Phone [phone]
            CIL House, Charlton Road, Andover SP10 3JL, UK


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Custom Interconnect Limited is a limited company registered in England and Wales. Registered number: 2026753. Registered office: CIL House 48 Charlton road Andover, Hampshire United Kingdom SP103JL.

[Craig Brideau]

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It really depends on your acquisition and what you are trying to see.  For
instance if you are using a camera with long exposure time then the ripples
will average out in the image and you won't have a problem.  On the other
hand if you are sampling at say ~120 Hz you will have alternating dim and
slightly brighter images.  This may be a problem your users can live with,
depending on what they are looking for.
Finally, if you are aware of the noise and its frequency AND it is
consistent then you can probably subtract it out post-processing.

Craig


On Mon, Nov 29, 2010 at 8:33 AM, Gordon Scott <[hidden email]>wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi Guys,
>
> I'm looking at ways to further improve the performance and efficiency of
> our light sources.
>
> There are always tradeoffs when doing this and I'd like to better
> understand what tradeoffs are acceptable for real microscopy users.
>
> Our present illumination sources all use a switched-mode pre-regulation
> and a linear final regulation for the LED power, so ripple is very low,
> but at a cost for us of some power wasted in the linear stages.
>
> I can improve that efficiency and reduce the waste by foregoing the
> linear stage and regulating directly with the switching mode, but the
> tradeoffs are a longer On/Off switching time than is feasible with
> linear, and a high-frequency ripple.
>
> My simulations suggest switch-on and switch-off times of around 50us and
> a ripple of around 25% at 100kHz, which would be reasonable from an
> electrical/energy point of view.
>
>
>
> The question is, of course, would any of the people likely to use it
> find that performance difficult or unacceptable?
>
>
>
> I've copied to the list rather than posting direct, so hopefully the
> replies will come to me rather than cluttering the list.
>
> Thanks for considering the question, even if you need not, or choose
> not, to answer.
>
> Kind regards,
>                 Gordon.
>  --
>  Gordon Scott  Design Engineering
>            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>            CoolLED                    http://www.coolled.com
>            CoolLED is a division of Custom Interconnect Ltd.
>            Phone [phone]
>            CIL House, Charlton Road, Andover SP10 3JL, UK
>
>
> This message has been scanned by MailController -
> www.MailController.altohiway.com
>
> This message and any attachments are strictly confidential and intended
> solely for the addressee. Any unauthorized use or disclosure, in whole or in
> part, is prohibited. E-mails are subject to possible alteration. Custom
> Interconnect Ltd and the sender decline any liability if this message and/or
> any attachments have been altered, changed or falsified. If you are not the
> intended recipient of this message, please delete it and notify the sender
> immediately.
>
> Custom Interconnect Limited is a limited company registered in England and
> Wales. Registered number: 2026753. Registered office: CIL House 48 Charlton
> road Andover, Hampshire United Kingdom SP103JL.
>

[Guy Cox-2]

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Gordon,

           Your strategy of copying to the list didn't seem to work.
Anyway, I think that lots of list members, having seen the question,
like to see the answers.

           If someone is taking conventional images with a 1 second
exposure 100kHz ripple will not be noticeable.  But if you are taking
video at 25 fps 525 line (international video) your line rate is about
13 kHz (US video about 14kHz) so I'd imagine there would be rather
unwelcome diagonal stripes on the image and you'd be getting angry phone
calls from your customers.  

                You haven't told us the other side of the trade-off.  Do
you want to eliminate the linear stage to save money - if so, how much
cheaper would it make a CooLED illuminator?  Or is it to save power?
How much would that save?  Given that an LED source already uses hugely
less power that an HBO 100 mercury lamp, would anyone care?

                                            Guy

Optical Imaging Techniques in Cell Biology
by Guy Cox    CRC Press / Taylor & Francis
     http://www.guycox.com/optical.htm
______________________________________________
Associate Professor Guy Cox, MA, DPhil(Oxon)
Australian Centre for Microscopy & Microanalysis,
Madsen Building F09, University of Sydney, NSW 2006

Phone [phone]     Fax [phone]
             Mobile [phone]
______________________________________________
      http://www.guycox.net
 

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]]
On Behalf Of Gordon Scott
Sent: Tuesday, 30 November 2010 2:34 AM
To: [hidden email]
Subject: Guidance wanted on illumination stability

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

I'm looking at ways to further improve the performance and efficiency of
our light sources.

There are always tradeoffs when doing this and I'd like to better
understand what tradeoffs are acceptable for real microscopy users.

Our present illumination sources all use a switched-mode pre-regulation
and a linear final regulation for the LED power, so ripple is very low,
but at a cost for us of some power wasted in the linear stages.

I can improve that efficiency and reduce the waste by foregoing the
linear stage and regulating directly with the switching mode, but the
tradeoffs are a longer On/Off switching time than is feasible with
linear, and a high-frequency ripple.

My simulations suggest switch-on and switch-off times of around 50us and
a ripple of around 25% at 100kHz, which would be reasonable from an
electrical/energy point of view.



The question is, of course, would any of the people likely to use it
find that performance difficult or unacceptable?



I've copied to the list rather than posting direct, so hopefully the
replies will come to me rather than cluttering the list.

Thanks for considering the question, even if you need not, or choose
not, to answer.

Kind regards,
                 Gordon.
 --
 Gordon Scott  Design Engineering
            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
            CoolLED                    http://www.coolled.com
            CoolLED is a division of Custom Interconnect Ltd.
            Phone [phone]
            CIL House, Charlton Road, Andover SP10 3JL, UK


This message has been scanned by MailController -
www.MailController.altohiway.com

This message and any attachments are strictly confidential and intended
solely for the addressee. Any unauthorized use or disclosure, in whole
or in part, is prohibited. E-mails are subject to possible alteration.
Custom Interconnect Ltd and the sender decline any liability if this
message and/or any attachments have been altered, changed or falsified.
If you are not the intended recipient of this message, please delete it
and notify the sender immediately.

Custom Interconnect Limited is a limited company registered in England
and Wales. Registered number: 2026753. Registered office: CIL House 48
Charlton road Andover, Hampshire United Kingdom SP103JL.

[Gordon Scott]

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Hi Craig,

Oh, my apologies, I'm inadvertently misleading the list here, sorry.

I'm part of CoolLED and I'm looking at how we improve and move forward
our illumination products.


My concern is that what we think might be acceptable in a new product
may not be acceptable to end users. My suspicion and also your 120Hz
sampling comment suggests that it quite possibly isn't and that I need
to keep the linear control. 100kHz/25% ripple at 120fps would appear to
be a brightness range around 0.025%, which should be invisible, I think.
On the other hand if the camera scans lines for whole frames, that jumps
to, say, 16% (640 lines), which is very likely intolerable.  I'm also
concerned about it in techniques like FLIM where time performance is
significant.

Thanks fro you comments.

Kind regards,
                  Gordon.
 --
 Gordon Scott  Design Engineering
            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
            CoolLED                    http://www.coolled.com
            CoolLED is a division of Custom Interconnect Ltd.
            Phone [phone]
            CIL House, Charlton Road, Andover SP10 3JL, UK
 

> -----Original Message-----
> From: Confocal Microscopy List
> [mailto:[hidden email]] On Behalf Of Craig Brideau
> Sent: 29 November 2010 17:56
> To: [hidden email]
> Subject: Re: Guidance wanted on illumination stability
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> It really depends on your acquisition and what you are trying
> to see.  For instance if you are using a camera with long
> exposure time then the ripples will average out in the image
> and you won't have a problem.  On the other hand if you are
> sampling at say ~120 Hz you will have alternating dim and
> slightly brighter images.  This may be a problem your users
> can live with, depending on what they are looking for.
> Finally, if you are aware of the noise and its frequency AND
> it is consistent then you can probably subtract it out
> post-processing.
>
> Craig
>
>
> On Mon, Nov 29, 2010 at 8:33 AM, Gordon Scott
> <[hidden email]>wrote:
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > *****
> >
> > Hi Guys,
> >
> > I'm looking at ways to further improve the performance and
> efficiency
> > of our light sources.
> >
> > There are always tradeoffs when doing this and I'd like to better
> > understand what tradeoffs are acceptable for real microscopy users.
> >
> > Our present illumination sources all use a switched-mode
> > pre-regulation and a linear final regulation for the LED power, so
> > ripple is very low, but at a cost for us of some power
> wasted in the linear stages.
> >
> > I can improve that efficiency and reduce the waste by foregoing the
> > linear stage and regulating directly with the switching
> mode, but the
> > tradeoffs are a longer On/Off switching time than is feasible with
> > linear, and a high-frequency ripple.
> >
> > My simulations suggest switch-on and switch-off times of
> around 50us
> > and a ripple of around 25% at 100kHz, which would be
> reasonable from
> > an electrical/energy point of view.
> >
> >
> >
> > The question is, of course, would any of the people likely
> to use it
> > find that performance difficult or unacceptable?
> >
> >
> >
> > I've copied to the list rather than posting direct, so
> hopefully the
> > replies will come to me rather than cluttering the list.
> >
> > Thanks for considering the question, even if you need not,
> or choose
> > not, to answer.
> >
> > Kind regards,
> >                 Gordon.
> >  --
> >  Gordon Scott  Design Engineering
> >            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
> >            CoolLED                    http://www.coolled.com
> >            CoolLED is a division of Custom Interconnect Ltd.
> >            Phone [phone]
> >            CIL House, Charlton Road, Andover SP10 3JL, UK
> >
> >
> > This message has been scanned by MailController -
> > www.MailController.altohiway.com
> >
> > This message and any attachments are strictly confidential and
> > intended solely for the addressee. Any unauthorized use or
> disclosure,
> > in whole or in part, is prohibited. E-mails are subject to possible
> > alteration. Custom Interconnect Ltd and the sender decline any
> > liability if this message and/or any attachments have been altered,
> > changed or falsified. If you are not the intended recipient of this
> > message, please delete it and notify the sender immediately.
> >
> > Custom Interconnect Limited is a limited company registered
> in England
> > and Wales. Registered number: 2026753. Registered office:
> CIL House 48
> > Charlton road Andover, Hampshire United Kingdom SP103JL.
> >
>

[Gordon Scott]

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

Hi Guy,

No the copy strategy didn't work. Of course one only finds that out
after the event. Ho Hum. :-(

My original thoughts on video were as yours, however I _think_ most
cameras take a full image and then the lines are downloaded
sequentially, but I'm also very aware that that may not be the whole, or
even the correct story. If the line rate _is_ important, and I guess if
the data is downloaded from the camera `live' line-by-line, rather than
as a complete image, then 100kHz will definitely show artefacts and the
case is closed .. I need to keep the linear control.

The main aim is actually to avoid unnecessary waste heat, though saving
money is always nice. I'm not sure it would make a particularly
significant effect on price, but it may. Any waste heat I have I then
have to get rid of.  LEDs must not get as hot as bulbs and indeed we
actively cool them to get the best out of them, so getting the excess
heat out of the boxes needs heat sinks and fans or similar. At present
that waste heat puts a frustrating limit on what's feasible with the
units, and I'd like to remove that frustration.

Thanks for your comments.

Kind regards,
                  Gordon.
 --
 Gordon Scott  Design Engineering
            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
            CoolLED                    http://www.coolled.com
            CoolLED is a division of Custom Interconnect Ltd.
            Phone [phone]
            CIL House, Charlton Road, Andover SP10 3JL, UK
 

> -----Original Message-----
> From: Guy Cox [mailto:[hidden email]]
> Sent: 29 November 2010 23:15
> To: Confocal Microscopy List
> Cc: Gordon Scott
> Subject: RE: Guidance wanted on illumination stability
>
> Gordon,
>
>            Your strategy of copying to the list didn't seem to work.
> Anyway, I think that lots of list members, having seen the
> question, like to see the answers.
>
>            If someone is taking conventional images with a 1
> second exposure 100kHz ripple will not be noticeable.  But if
> you are taking video at 25 fps 525 line (international video)
> your line rate is about
> 13 kHz (US video about 14kHz) so I'd imagine there would be
> rather unwelcome diagonal stripes on the image and you'd be
> getting angry phone calls from your customers.  
>
> You haven't told us the other side of the
> trade-off.  Do you want to eliminate the linear stage to save
> money - if so, how much cheaper would it make a CooLED
> illuminator?  Or is it to save power?
> How much would that save?  Given that an LED source already
> uses hugely less power that an HBO 100 mercury lamp, would
> anyone care?
>
>                                             Guy
>
> Optical Imaging Techniques in Cell Biology
> by Guy Cox    CRC Press / Taylor & Francis
>      http://www.guycox.com/optical.htm
> ______________________________________________
> Associate Professor Guy Cox, MA, DPhil(Oxon) Australian
> Centre for Microscopy & Microanalysis, Madsen Building F09,
> University of Sydney, NSW 2006
>
> Phone [phone]     Fax [phone]
>              Mobile [phone]
> ______________________________________________
>       http://www.guycox.net
>  
>
> -----Original Message-----
> From: Confocal Microscopy List
> [mailto:[hidden email]]
> On Behalf Of Gordon Scott
> Sent: Tuesday, 30 November 2010 2:34 AM
> To: [hidden email]
> Subject: Guidance wanted on illumination stability
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi Guys,
>
> I'm looking at ways to further improve the performance and
> efficiency of our light sources.
>
> There are always tradeoffs when doing this and I'd like to
> better understand what tradeoffs are acceptable for real
> microscopy users.
>
> Our present illumination sources all use a switched-mode
> pre-regulation and a linear final regulation for the LED
> power, so ripple is very low, but at a cost for us of some
> power wasted in the linear stages.
>
> I can improve that efficiency and reduce the waste by
> foregoing the linear stage and regulating directly with the
> switching mode, but the tradeoffs are a longer On/Off
> switching time than is feasible with linear, and a
> high-frequency ripple.
>
> My simulations suggest switch-on and switch-off times of
> around 50us and a ripple of around 25% at 100kHz, which would
> be reasonable from an electrical/energy point of view.
>
>
>
> The question is, of course, would any of the people likely to
> use it find that performance difficult or unacceptable?
>
>
>
> I've copied to the list rather than posting direct, so
> hopefully the replies will come to me rather than cluttering the list.
>
> Thanks for considering the question, even if you need not, or
> choose not, to answer.
>
> Kind regards,
> Gordon.
>  --
>  Gordon Scott  Design Engineering
>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>    CoolLED                    http://www.coolled.com
>    CoolLED is a division of Custom Interconnect Ltd.
>    Phone [phone]
>    CIL House, Charlton Road, Andover SP10 3JL, UK
>
>
> This message has been scanned by MailController -
> www.MailController.altohiway.com
>
> This message and any attachments are strictly confidential
> and intended solely for the addressee. Any unauthorized use
> or disclosure, in whole or in part, is prohibited. E-mails
> are subject to possible alteration.
> Custom Interconnect Ltd and the sender decline any liability
> if this message and/or any attachments have been altered,
> changed or falsified.
> If you are not the intended recipient of this message, please
> delete it and notify the sender immediately.
>
> Custom Interconnect Limited is a limited company registered
> in England and Wales. Registered number: 2026753. Registered
> office: CIL House 48 Charlton road Andover, Hampshire United
> Kingdom SP103JL.
>

[Jeremy Adler-3]

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

It might also be useful to have pulsatile LEDs operating in the  
nanosecond range - there was a Stefan Hell paper that showed very  
significant reductions in photobleaching when the gap between pulses  
was longer than the fluorescent lifetime. Is this possible with LEDs ?


Quoting Gordon Scott <[hidden email]>:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi Guy,
>
> No the copy strategy didn't work. Of course one only finds that out
> after the event. Ho Hum. :-(
>
> My original thoughts on video were as yours, however I _think_ most
> cameras take a full image and then the lines are downloaded
> sequentially, but I'm also very aware that that may not be the whole, or
> even the correct story. If the line rate _is_ important, and I guess if
> the data is downloaded from the camera `live' line-by-line, rather than
> as a complete image, then 100kHz will definitely show artefacts and the
> case is closed .. I need to keep the linear control.
>
> The main aim is actually to avoid unnecessary waste heat, though saving
> money is always nice. I'm not sure it would make a particularly
> significant effect on price, but it may. Any waste heat I have I then
> have to get rid of.  LEDs must not get as hot as bulbs and indeed we
> actively cool them to get the best out of them, so getting the excess
> heat out of the boxes needs heat sinks and fans or similar. At present
> that waste heat puts a frustrating limit on what's feasible with the
> units, and I'd like to remove that frustration.
>
> Thanks for your comments.
>
> Kind regards,
>  Gordon.
>  --
>  Gordon Scott  Design Engineering
>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>    CoolLED                    http://www.coolled.com
>    CoolLED is a division of Custom Interconnect Ltd.
>    Phone [phone]
>    CIL House, Charlton Road, Andover SP10 3JL, UK
>
>
>> -----Original Message-----
>> From: Guy Cox [mailto:[hidden email]]
>> Sent: 29 November 2010 23:15
>> To: Confocal Microscopy List
>> Cc: Gordon Scott
>> Subject: RE: Guidance wanted on illumination stability
>>
>> Gordon,
>>
>>            Your strategy of copying to the list didn't seem to work.
>> Anyway, I think that lots of list members, having seen the
>> question, like to see the answers.
>>
>>            If someone is taking conventional images with a 1
>> second exposure 100kHz ripple will not be noticeable.  But if
>> you are taking video at 25 fps 525 line (international video)
>> your line rate is about
>> 13 kHz (US video about 14kHz) so I'd imagine there would be
>> rather unwelcome diagonal stripes on the image and you'd be
>> getting angry phone calls from your customers.
>>
>> You haven't told us the other side of the
>> trade-off.  Do you want to eliminate the linear stage to save
>> money - if so, how much cheaper would it make a CooLED
>> illuminator?  Or is it to save power?
>> How much would that save?  Given that an LED source already
>> uses hugely less power that an HBO 100 mercury lamp, would
>> anyone care?
>>
>>                                             Guy
>>
>> Optical Imaging Techniques in Cell Biology
>> by Guy Cox    CRC Press / Taylor & Francis
>>      http://www.guycox.com/optical.htm
>> ______________________________________________
>> Associate Professor Guy Cox, MA, DPhil(Oxon) Australian
>> Centre for Microscopy & Microanalysis, Madsen Building F09,
>> University of Sydney, NSW 2006
>>
>> Phone [phone]     Fax [phone]
>>              Mobile [phone]
>> ______________________________________________
>>       http://www.guycox.net
>>
>>
>> -----Original Message-----
>> From: Confocal Microscopy List
>> [mailto:[hidden email]]
>> On Behalf Of Gordon Scott
>> Sent: Tuesday, 30 November 2010 2:34 AM
>> To: [hidden email]
>> Subject: Guidance wanted on illumination stability
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> Hi Guys,
>>
>> I'm looking at ways to further improve the performance and
>> efficiency of our light sources.
>>
>> There are always tradeoffs when doing this and I'd like to
>> better understand what tradeoffs are acceptable for real
>> microscopy users.
>>
>> Our present illumination sources all use a switched-mode
>> pre-regulation and a linear final regulation for the LED
>> power, so ripple is very low, but at a cost for us of some
>> power wasted in the linear stages.
>>
>> I can improve that efficiency and reduce the waste by
>> foregoing the linear stage and regulating directly with the
>> switching mode, but the tradeoffs are a longer On/Off
>> switching time than is feasible with linear, and a
>> high-frequency ripple.
>>
>> My simulations suggest switch-on and switch-off times of
>> around 50us and a ripple of around 25% at 100kHz, which would
>> be reasonable from an electrical/energy point of view.
>>
>>
>>
>> The question is, of course, would any of the people likely to
>> use it find that performance difficult or unacceptable?
>>
>>
>>
>> I've copied to the list rather than posting direct, so
>> hopefully the replies will come to me rather than cluttering the list.
>>
>> Thanks for considering the question, even if you need not, or
>> choose not, to answer.
>>
>> Kind regards,
>> Gordon.
>>  --
>>  Gordon Scott  Design Engineering
>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>    CoolLED                    http://www.coolled.com
>>    CoolLED is a division of Custom Interconnect Ltd.
>>    Phone [phone]
>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>
>>
>> This message has been scanned by MailController -
>> www.MailController.altohiway.com
>>
>> This message and any attachments are strictly confidential
>> and intended solely for the addressee. Any unauthorized use
>> or disclosure, in whole or in part, is prohibited. E-mails
>> are subject to possible alteration.
>> Custom Interconnect Ltd and the sender decline any liability
>> if this message and/or any attachments have been altered,
>> changed or falsified.
>> If you are not the intended recipient of this message, please
>> delete it and notify the sender immediately.
>>
>> Custom Interconnect Limited is a limited company registered
>> in England and Wales. Registered number: 2026753. Registered
>> office: CIL House 48 Charlton road Andover, Hampshire United
>> Kingdom SP103JL.
>>
>

Jeremy Adler
Genetics & Pathology
Rudbeckslaboratoriet
Daghammersköljdsväg 20
751 85 Uppsala
Sweden

0046 (0)18 471 4607

[Knecht, David]

*****
To join, leave or search the confocal microscopy listserv, go to:
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*****

It is not only possible, but Thorlabs sells an LED controller that modulates LED intensity in this way up to 10kHz which I think should be adequate for the effect discussed in the Hell paper.  I have not had a chance to try it yet and see if it works to reduce bleaching.  Dave
http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=4003

On Nov 30, 2010, at 10:26 AM, Jeremy Adler wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> It might also be useful to have pulsatile LEDs operating in the  
> nanosecond range - there was a Stefan Hell paper that showed very  
> significant reductions in photobleaching when the gap between pulses  
> was longer than the fluorescent lifetime. Is this possible with LEDs ?
>
>
> Quoting Gordon Scott <[hidden email]>:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> Hi Guy,
>>
>> No the copy strategy didn't work. Of course one only finds that out
>> after the event. Ho Hum. :-(
>>
>> My original thoughts on video were as yours, however I _think_ most
>> cameras take a full image and then the lines are downloaded
>> sequentially, but I'm also very aware that that may not be the whole, or
>> even the correct story. If the line rate _is_ important, and I guess if
>> the data is downloaded from the camera `live' line-by-line, rather than
>> as a complete image, then 100kHz will definitely show artefacts and the
>> case is closed .. I need to keep the linear control.
>>
>> The main aim is actually to avoid unnecessary waste heat, though saving
>> money is always nice. I'm not sure it would make a particularly
>> significant effect on price, but it may. Any waste heat I have I then
>> have to get rid of.  LEDs must not get as hot as bulbs and indeed we
>> actively cool them to get the best out of them, so getting the excess
>> heat out of the boxes needs heat sinks and fans or similar. At present
>> that waste heat puts a frustrating limit on what's feasible with the
>> units, and I'd like to remove that frustration.
>>
>> Thanks for your comments.
>>
>> Kind regards,
>>  Gordon.
>> --
>> Gordon Scott  Design Engineering
>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>    CoolLED                    http://www.coolled.com
>>    CoolLED is a division of Custom Interconnect Ltd.
>>    Phone [phone]
>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>
>>
>>> -----Original Message-----
>>> From: Guy Cox [mailto:[hidden email]]
>>> Sent: 29 November 2010 23:15
>>> To: Confocal Microscopy List
>>> Cc: Gordon Scott
>>> Subject: RE: Guidance wanted on illumination stability
>>>
>>> Gordon,
>>>
>>>           Your strategy of copying to the list didn't seem to work.
>>> Anyway, I think that lots of list members, having seen the
>>> question, like to see the answers.
>>>
>>>           If someone is taking conventional images with a 1
>>> second exposure 100kHz ripple will not be noticeable.  But if
>>> you are taking video at 25 fps 525 line (international video)
>>> your line rate is about
>>> 13 kHz (US video about 14kHz) so I'd imagine there would be
>>> rather unwelcome diagonal stripes on the image and you'd be
>>> getting angry phone calls from your customers.
>>>
>>> You haven't told us the other side of the
>>> trade-off.  Do you want to eliminate the linear stage to save
>>> money - if so, how much cheaper would it make a CooLED
>>> illuminator?  Or is it to save power?
>>> How much would that save?  Given that an LED source already
>>> uses hugely less power that an HBO 100 mercury lamp, would
>>> anyone care?
>>>
>>>                                            Guy
>>>
>>> Optical Imaging Techniques in Cell Biology
>>> by Guy Cox    CRC Press / Taylor & Francis
>>>     http://www.guycox.com/optical.htm
>>> ______________________________________________
>>> Associate Professor Guy Cox, MA, DPhil(Oxon) Australian
>>> Centre for Microscopy & Microanalysis, Madsen Building F09,
>>> University of Sydney, NSW 2006
>>>
>>> Phone [phone]     Fax [phone]
>>>             Mobile [phone]
>>> ______________________________________________
>>>      http://www.guycox.net
>>>
>>>
>>> -----Original Message-----
>>> From: Confocal Microscopy List
>>> [mailto:[hidden email]]
>>> On Behalf Of Gordon Scott
>>> Sent: Tuesday, 30 November 2010 2:34 AM
>>> To: [hidden email]
>>> Subject: Guidance wanted on illumination stability
>>>
>>> *****
>>> To join, leave or search the confocal microscopy listserv, go to:
>>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>> *****
>>>
>>> Hi Guys,
>>>
>>> I'm looking at ways to further improve the performance and
>>> efficiency of our light sources.
>>>
>>> There are always tradeoffs when doing this and I'd like to
>>> better understand what tradeoffs are acceptable for real
>>> microscopy users.
>>>
>>> Our present illumination sources all use a switched-mode
>>> pre-regulation and a linear final regulation for the LED
>>> power, so ripple is very low, but at a cost for us of some
>>> power wasted in the linear stages.
>>>
>>> I can improve that efficiency and reduce the waste by
>>> foregoing the linear stage and regulating directly with the
>>> switching mode, but the tradeoffs are a longer On/Off
>>> switching time than is feasible with linear, and a
>>> high-frequency ripple.
>>>
>>> My simulations suggest switch-on and switch-off times of
>>> around 50us and a ripple of around 25% at 100kHz, which would
>>> be reasonable from an electrical/energy point of view.
>>>
>>>
>>>
>>> The question is, of course, would any of the people likely to
>>> use it find that performance difficult or unacceptable?
>>>
>>>
>>>
>>> I've copied to the list rather than posting direct, so
>>> hopefully the replies will come to me rather than cluttering the list.
>>>
>>> Thanks for considering the question, even if you need not, or
>>> choose not, to answer.
>>>
>>> Kind regards,
>>> Gordon.
>>> --
>>> Gordon Scott  Design Engineering
>>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>>    CoolLED                    http://www.coolled.com
>>>    CoolLED is a division of Custom Interconnect Ltd.
>>>    Phone [phone]
>>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>>
>>>
>>> This message has been scanned by MailController -
>>> www.MailController.altohiway.com
>>>
>>> This message and any attachments are strictly confidential
>>> and intended solely for the addressee. Any unauthorized use
>>> or disclosure, in whole or in part, is prohibited. E-mails
>>> are subject to possible alteration.
>>> Custom Interconnect Ltd and the sender decline any liability
>>> if this message and/or any attachments have been altered,
>>> changed or falsified.
>>> If you are not the intended recipient of this message, please
>>> delete it and notify the sender immediately.
>>>
>>> Custom Interconnect Limited is a limited company registered
>>> in England and Wales. Registered number: 2026753. Registered
>>> office: CIL House 48 Charlton road Andover, Hampshire United
>>> Kingdom SP103JL.
>>>
>>
>
>
>
> Jeremy Adler
> Genetics & Pathology
> Rudbeckslaboratoriet
> Daghammersköljdsväg 20
> 751 85 Uppsala
> Sweden
>
> 0046 (0)18 471 4607

Dr. David Knecht    
Department of Molecular and Cell Biology
Co-head Flow Cytometry and Confocal Microscopy Facility
U-3125
91 N. Eagleville Rd.
University of Connecticut
Storrs, CT 06269
860-486-2200
860-486-4331 (fax)

[Craig Brideau]

*****
To join, leave or search the confocal microscopy listserv, go to:
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*****

Yeah, the bottom line is as long as your 'flicker' is not visible within the
time-frame of acquisition you should be fine.
Regarding the power supply comments, shouldn't it be possible to build a
sufficiently stable current source for the LEDs?  Of course I suppose for a
commercial product you want to keep the costs down.  Some
data acquisition gear I've seen runs off dual rechargeable batteries.  They
produce pure DC so no ripple, and while one battery runs the equipment the
other charges off wall current.  They switch off as necessary to keep the
gear running.  Again though this may be unnecessarily complex if the ripple
proves not to be a problem.

Craig


On Tue, Nov 30, 2010 at 2:49 AM, Gordon Scott <[hidden email]>wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi Craig,
>
> Oh, my apologies, I'm inadvertently misleading the list here, sorry.
>
> I'm part of CoolLED and I'm looking at how we improve and move forward
> our illumination products.
>
>
> My concern is that what we think might be acceptable in a new product
> may not be acceptable to end users. My suspicion and also your 120Hz
> sampling comment suggests that it quite possibly isn't and that I need
> to keep the linear control. 100kHz/25% ripple at 120fps would appear to
> be a brightness range around 0.025%, which should be invisible, I think.
> On the other hand if the camera scans lines for whole frames, that jumps
> to, say, 16% (640 lines), which is very likely intolerable.  I'm also
> concerned about it in techniques like FLIM where time performance is
> significant.
>
> Thanks fro you comments.
>
> Kind regards,
>                  Gordon.
>  --
>  Gordon Scott  Design Engineering
>            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>            CoolLED                    http://www.coolled.com
>            CoolLED is a division of Custom Interconnect Ltd.
>            Phone [phone]
>            CIL House, Charlton Road, Andover SP10 3JL, UK
>
>
> > -----Original Message-----
> > From: Confocal Microscopy List
> > [mailto:[hidden email]] On Behalf Of Craig Brideau
> > Sent: 29 November 2010 17:56
> > To: [hidden email]
> > Subject: Re: Guidance wanted on illumination stability
> >
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > *****
> >
> > It really depends on your acquisition and what you are trying
> > to see.  For instance if you are using a camera with long
> > exposure time then the ripples will average out in the image
> > and you won't have a problem.  On the other hand if you are
> > sampling at say ~120 Hz you will have alternating dim and
> > slightly brighter images.  This may be a problem your users
> > can live with, depending on what they are looking for.
> > Finally, if you are aware of the noise and its frequency AND
> > it is consistent then you can probably subtract it out
> > post-processing.
> >
> > Craig
> >
> >
> > On Mon, Nov 29, 2010 at 8:33 AM, Gordon Scott
> > <[hidden email]>wrote:
> >
> > > *****
> > > To join, leave or search the confocal microscopy listserv, go to:
> > > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > > *****
> > >
> > > Hi Guys,
> > >
> > > I'm looking at ways to further improve the performance and
> > efficiency
> > > of our light sources.
> > >
> > > There are always tradeoffs when doing this and I'd like to better
> > > understand what tradeoffs are acceptable for real microscopy users.
> > >
> > > Our present illumination sources all use a switched-mode
> > > pre-regulation and a linear final regulation for the LED power, so
> > > ripple is very low, but at a cost for us of some power
> > wasted in the linear stages.
> > >
> > > I can improve that efficiency and reduce the waste by foregoing the
> > > linear stage and regulating directly with the switching
> > mode, but the
> > > tradeoffs are a longer On/Off switching time than is feasible with
> > > linear, and a high-frequency ripple.
> > >
> > > My simulations suggest switch-on and switch-off times of
> > around 50us
> > > and a ripple of around 25% at 100kHz, which would be
> > reasonable from
> > > an electrical/energy point of view.
> > >
> > >
> > >
> > > The question is, of course, would any of the people likely
> > to use it
> > > find that performance difficult or unacceptable?
> > >
> > >
> > >
> > > I've copied to the list rather than posting direct, so
> > hopefully the
> > > replies will come to me rather than cluttering the list.
> > >
> > > Thanks for considering the question, even if you need not,
> > or choose
> > > not, to answer.
> > >
> > > Kind regards,
> > >                 Gordon.
> > >  --
> > >  Gordon Scott  Design Engineering
> > >            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
> > >            CoolLED                    http://www.coolled.com
> > >            CoolLED is a division of Custom Interconnect Ltd.
> > >            Phone [phone]
> > >            CIL House, Charlton Road, Andover SP10 3JL, UK
> > >
> > >
> > > This message has been scanned by MailController -
> > > www.MailController.altohiway.com
> > >
> > > This message and any attachments are strictly confidential and
> > > intended solely for the addressee. Any unauthorized use or
> > disclosure,
> > > in whole or in part, is prohibited. E-mails are subject to possible
> > > alteration. Custom Interconnect Ltd and the sender decline any
> > > liability if this message and/or any attachments have been altered,
> > > changed or falsified. If you are not the intended recipient of this
> > > message, please delete it and notify the sender immediately.
> > >
> > > Custom Interconnect Limited is a limited company registered
> > in England
> > > and Wales. Registered number: 2026753. Registered office:
> > CIL House 48
> > > Charlton road Andover, Hampshire United Kingdom SP103JL.
> > >
> >
>

[Ignatius, Mike-2]

*****
To join, leave or search the confocal microscopy listserv, go to:
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*****

Prior to Dr. Hell's excellent 2007 paper cited below using laser light pulses in the ns range, Dr. Nishigaki et al, in 2006 used the LED approach successfully, though with more modest gains.  They custom built a pulsed diode with broader duty cycle (0.5 to 2ms) that reduced bleaching of organic dyes and associated cell toxicity.   Apparently driving diodes much faster than this raises heating concerns.  

Or is this no longer true?

Stroboscopic illumination using light-emitting diodes reduces phototoxicity in fluorescence cell imaging.  Nishigaki T, Wood CD, Shiba K, Baba SA, Darszon A. Biotechniques. 2006 Aug;41(2):191-7.

Mike Ignatius
Molecular Probes, Life Technologies


-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Jeremy Adler
Sent: Tuesday, November 30, 2010 7:27 AM
To: [hidden email]
Subject: Re: Guidance wanted on illumination stability

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

It might also be useful to have pulsatile LEDs operating in the  
nanosecond range - there was a Stefan Hell paper that showed very  
significant reductions in photobleaching when the gap between pulses  
was longer than the fluorescent lifetime. Is this possible with LEDs ?


Quoting Gordon Scott <[hidden email]>:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> Hi Guy,
>
> No the copy strategy didn't work. Of course one only finds that out
> after the event. Ho Hum. :-(
>
> My original thoughts on video were as yours, however I _think_ most
> cameras take a full image and then the lines are downloaded
> sequentially, but I'm also very aware that that may not be the whole, or
> even the correct story. If the line rate _is_ important, and I guess if
> the data is downloaded from the camera `live' line-by-line, rather than
> as a complete image, then 100kHz will definitely show artefacts and the
> case is closed .. I need to keep the linear control.
>
> The main aim is actually to avoid unnecessary waste heat, though saving
> money is always nice. I'm not sure it would make a particularly
> significant effect on price, but it may. Any waste heat I have I then
> have to get rid of.  LEDs must not get as hot as bulbs and indeed we
> actively cool them to get the best out of them, so getting the excess
> heat out of the boxes needs heat sinks and fans or similar. At present
> that waste heat puts a frustrating limit on what's feasible with the
> units, and I'd like to remove that frustration.
>
> Thanks for your comments.
>
> Kind regards,
>  Gordon.
>  --
>  Gordon Scott  Design Engineering
>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>    CoolLED                    http://www.coolled.com
>    CoolLED is a division of Custom Interconnect Ltd.
>    Phone [phone]
>    CIL House, Charlton Road, Andover SP10 3JL, UK
>
>
>> -----Original Message-----
>> From: Guy Cox [mailto:[hidden email]]
>> Sent: 29 November 2010 23:15
>> To: Confocal Microscopy List
>> Cc: Gordon Scott
>> Subject: RE: Guidance wanted on illumination stability
>>
>> Gordon,
>>
>>            Your strategy of copying to the list didn't seem to work.
>> Anyway, I think that lots of list members, having seen the
>> question, like to see the answers.
>>
>>            If someone is taking conventional images with a 1
>> second exposure 100kHz ripple will not be noticeable.  But if
>> you are taking video at 25 fps 525 line (international video)
>> your line rate is about
>> 13 kHz (US video about 14kHz) so I'd imagine there would be
>> rather unwelcome diagonal stripes on the image and you'd be
>> getting angry phone calls from your customers.
>>
>> You haven't told us the other side of the
>> trade-off.  Do you want to eliminate the linear stage to save
>> money - if so, how much cheaper would it make a CooLED
>> illuminator?  Or is it to save power?
>> How much would that save?  Given that an LED source already
>> uses hugely less power that an HBO 100 mercury lamp, would
>> anyone care?
>>
>>                                             Guy
>>
>> Optical Imaging Techniques in Cell Biology
>> by Guy Cox    CRC Press / Taylor & Francis
>>      http://www.guycox.com/optical.htm
>> ______________________________________________
>> Associate Professor Guy Cox, MA, DPhil(Oxon) Australian
>> Centre for Microscopy & Microanalysis, Madsen Building F09,
>> University of Sydney, NSW 2006
>>
>> Phone [phone]     Fax [phone]
>>              Mobile [phone]
>> ______________________________________________
>>       http://www.guycox.net
>>
>>
>> -----Original Message-----
>> From: Confocal Microscopy List
>> [mailto:[hidden email]]
>> On Behalf Of Gordon Scott
>> Sent: Tuesday, 30 November 2010 2:34 AM
>> To: [hidden email]
>> Subject: Guidance wanted on illumination stability
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> Hi Guys,
>>
>> I'm looking at ways to further improve the performance and
>> efficiency of our light sources.
>>
>> There are always tradeoffs when doing this and I'd like to
>> better understand what tradeoffs are acceptable for real
>> microscopy users.
>>
>> Our present illumination sources all use a switched-mode
>> pre-regulation and a linear final regulation for the LED
>> power, so ripple is very low, but at a cost for us of some
>> power wasted in the linear stages.
>>
>> I can improve that efficiency and reduce the waste by
>> foregoing the linear stage and regulating directly with the
>> switching mode, but the tradeoffs are a longer On/Off
>> switching time than is feasible with linear, and a
>> high-frequency ripple.
>>
>> My simulations suggest switch-on and switch-off times of
>> around 50us and a ripple of around 25% at 100kHz, which would
>> be reasonable from an electrical/energy point of view.
>>
>>
>>
>> The question is, of course, would any of the people likely to
>> use it find that performance difficult or unacceptable?
>>
>>
>>
>> I've copied to the list rather than posting direct, so
>> hopefully the replies will come to me rather than cluttering the list.
>>
>> Thanks for considering the question, even if you need not, or
>> choose not, to answer.
>>
>> Kind regards,
>> Gordon.
>>  --
>>  Gordon Scott  Design Engineering
>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>    CoolLED                    http://www.coolled.com
>>    CoolLED is a division of Custom Interconnect Ltd.
>>    Phone [phone]
>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>
>>
>> This message has been scanned by MailController -
>> www.MailController.altohiway.com
>>
>> This message and any attachments are strictly confidential
>> and intended solely for the addressee. Any unauthorized use
>> or disclosure, in whole or in part, is prohibited. E-mails
>> are subject to possible alteration.
>> Custom Interconnect Ltd and the sender decline any liability
>> if this message and/or any attachments have been altered,
>> changed or falsified.
>> If you are not the intended recipient of this message, please
>> delete it and notify the sender immediately.
>>
>> Custom Interconnect Limited is a limited company registered
>> in England and Wales. Registered number: 2026753. Registered
>> office: CIL House 48 Charlton road Andover, Hampshire United
>> Kingdom SP103JL.
>>
>

Jeremy Adler
Genetics & Pathology
Rudbeckslaboratoriet
Daghammersköljdsväg 20
751 85 Uppsala
Sweden

0046 (0)18 471 4607

[Jeremy Adler-3]

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

re bleaching and pulse duration, the rationale for nanosecond pulses  
with similar interval between pulses was to avoid second photon hits  
during the time the fluorophore was in the excited state - which means  
that 10kHz is way off the mark.



Quoting David Knecht <[hidden email]>:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
>
> It is not only possible, but Thorlabs sells an LED controller that  
> modulates LED intensity in this way up to 10kHz which I think should  
>  be adequate for the effect discussed in the Hell paper.  I have not  
>  had a chance to try it yet and see if it works to reduce bleaching.  
>   Dave
> http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=4003
>
> On Nov 30, 2010, at 10:26 AM, Jeremy Adler wrote:
>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> It might also be useful to have pulsatile LEDs operating in the
>> nanosecond range - there was a Stefan Hell paper that showed very
>> significant reductions in photobleaching when the gap between pulses
>> was longer than the fluorescent lifetime. Is this possible with LEDs ?
>>
>>
>> Quoting Gordon Scott <[hidden email]>:
>>
>>> *****
>>> To join, leave or search the confocal microscopy listserv, go to:
>>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>> *****
>>>
>>> Hi Guy,
>>>
>>> No the copy strategy didn't work. Of course one only finds that out
>>> after the event. Ho Hum. :-(
>>>
>>> My original thoughts on video were as yours, however I _think_ most
>>> cameras take a full image and then the lines are downloaded
>>> sequentially, but I'm also very aware that that may not be the whole, or
>>> even the correct story. If the line rate _is_ important, and I guess if
>>> the data is downloaded from the camera `live' line-by-line, rather than
>>> as a complete image, then 100kHz will definitely show artefacts and the
>>> case is closed .. I need to keep the linear control.
>>>
>>> The main aim is actually to avoid unnecessary waste heat, though saving
>>> money is always nice. I'm not sure it would make a particularly
>>> significant effect on price, but it may. Any waste heat I have I then
>>> have to get rid of.  LEDs must not get as hot as bulbs and indeed we
>>> actively cool them to get the best out of them, so getting the excess
>>> heat out of the boxes needs heat sinks and fans or similar. At present
>>> that waste heat puts a frustrating limit on what's feasible with the
>>> units, and I'd like to remove that frustration.
>>>
>>> Thanks for your comments.
>>>
>>> Kind regards,
>>>  Gordon.
>>> --
>>> Gordon Scott  Design Engineering
>>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>>    CoolLED                    http://www.coolled.com
>>>    CoolLED is a division of Custom Interconnect Ltd.
>>>    Phone [phone]
>>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>>
>>>
>>>> -----Original Message-----
>>>> From: Guy Cox [mailto:[hidden email]]
>>>> Sent: 29 November 2010 23:15
>>>> To: Confocal Microscopy List
>>>> Cc: Gordon Scott
>>>> Subject: RE: Guidance wanted on illumination stability
>>>>
>>>> Gordon,
>>>>
>>>>           Your strategy of copying to the list didn't seem to work.
>>>> Anyway, I think that lots of list members, having seen the
>>>> question, like to see the answers.
>>>>
>>>>           If someone is taking conventional images with a 1
>>>> second exposure 100kHz ripple will not be noticeable.  But if
>>>> you are taking video at 25 fps 525 line (international video)
>>>> your line rate is about
>>>> 13 kHz (US video about 14kHz) so I'd imagine there would be
>>>> rather unwelcome diagonal stripes on the image and you'd be
>>>> getting angry phone calls from your customers.
>>>>
>>>> You haven't told us the other side of the
>>>> trade-off.  Do you want to eliminate the linear stage to save
>>>> money - if so, how much cheaper would it make a CooLED
>>>> illuminator?  Or is it to save power?
>>>> How much would that save?  Given that an LED source already
>>>> uses hugely less power that an HBO 100 mercury lamp, would
>>>> anyone care?
>>>>
>>>>                                            Guy
>>>>
>>>> Optical Imaging Techniques in Cell Biology
>>>> by Guy Cox    CRC Press / Taylor & Francis
>>>>     http://www.guycox.com/optical.htm
>>>> ______________________________________________
>>>> Associate Professor Guy Cox, MA, DPhil(Oxon) Australian
>>>> Centre for Microscopy & Microanalysis, Madsen Building F09,
>>>> University of Sydney, NSW 2006
>>>>
>>>> Phone [phone]     Fax [phone]
>>>>             Mobile [phone]
>>>> ______________________________________________
>>>>      http://www.guycox.net
>>>>
>>>>
>>>> -----Original Message-----
>>>> From: Confocal Microscopy List
>>>> [mailto:[hidden email]]
>>>> On Behalf Of Gordon Scott
>>>> Sent: Tuesday, 30 November 2010 2:34 AM
>>>> To: [hidden email]
>>>> Subject: Guidance wanted on illumination stability
>>>>
>>>> *****
>>>> To join, leave or search the confocal microscopy listserv, go to:
>>>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>>> *****
>>>>
>>>> Hi Guys,
>>>>
>>>> I'm looking at ways to further improve the performance and
>>>> efficiency of our light sources.
>>>>
>>>> There are always tradeoffs when doing this and I'd like to
>>>> better understand what tradeoffs are acceptable for real
>>>> microscopy users.
>>>>
>>>> Our present illumination sources all use a switched-mode
>>>> pre-regulation and a linear final regulation for the LED
>>>> power, so ripple is very low, but at a cost for us of some
>>>> power wasted in the linear stages.
>>>>
>>>> I can improve that efficiency and reduce the waste by
>>>> foregoing the linear stage and regulating directly with the
>>>> switching mode, but the tradeoffs are a longer On/Off
>>>> switching time than is feasible with linear, and a
>>>> high-frequency ripple.
>>>>
>>>> My simulations suggest switch-on and switch-off times of
>>>> around 50us and a ripple of around 25% at 100kHz, which would
>>>> be reasonable from an electrical/energy point of view.
>>>>
>>>>
>>>>
>>>> The question is, of course, would any of the people likely to
>>>> use it find that performance difficult or unacceptable?
>>>>
>>>>
>>>>
>>>> I've copied to the list rather than posting direct, so
>>>> hopefully the replies will come to me rather than cluttering the list.
>>>>
>>>> Thanks for considering the question, even if you need not, or
>>>> choose not, to answer.
>>>>
>>>> Kind regards,
>>>> Gordon.
>>>> --
>>>> Gordon Scott  Design Engineering
>>>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>>>    CoolLED                    http://www.coolled.com
>>>>    CoolLED is a division of Custom Interconnect Ltd.
>>>>    Phone [phone]
>>>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>>>
>>>>
>>>> This message has been scanned by MailController -
>>>> www.MailController.altohiway.com
>>>>
>>>> This message and any attachments are strictly confidential
>>>> and intended solely for the addressee. Any unauthorized use
>>>> or disclosure, in whole or in part, is prohibited. E-mails
>>>> are subject to possible alteration.
>>>> Custom Interconnect Ltd and the sender decline any liability
>>>> if this message and/or any attachments have been altered,
>>>> changed or falsified.
>>>> If you are not the intended recipient of this message, please
>>>> delete it and notify the sender immediately.
>>>>
>>>> Custom Interconnect Limited is a limited company registered
>>>> in England and Wales. Registered number: 2026753. Registered
>>>> office: CIL House 48 Charlton road Andover, Hampshire United
>>>> Kingdom SP103JL.
>>>>
>>>
>>
>>
>>
>> Jeremy Adler
>> Genetics & Pathology
>> Rudbeckslaboratoriet
>> Daghammersköljdsväg 20
>> 751 85 Uppsala
>> Sweden
>>
>> 0046 (0)18 471 4607
>
> Dr. David Knecht
> Department of Molecular and Cell Biology
> Co-head Flow Cytometry and Confocal Microscopy Facility
> U-3125
> 91 N. Eagleville Rd.
> University of Connecticut
> Storrs, CT 06269
> 860-486-2200
> 860-486-4331 (fax)
>

Jeremy Adler
Genetics & Pathology
Rudbeckslaboratoriet
Daghammersköljdsväg 20
751 85 Uppsala
Sweden

0046 (0)18 471 4607

[Gordon Scott]

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Hi Jeremy,

> [mailto:[hidden email]] On Behalf Of Jeremy Adler
 
> It might also be useful to have pulsatile LEDs operating in
> the nanosecond range - there was a Stefan Hell paper that
> showed very significant reductions in photobleaching when the
> gap between pulses was longer than the fluorescent lifetime.
> Is this possible with LEDs ?

Pulses of multiple nanoseconds duration should be feasible enough,
though not with the architecture of our present products, which are
speed constrained due to the smoothing/linearisation we use. Our present
units run to around 10kHz and we know we can make them run to around
300kHz with some modest changes that will likely roll out in the
standard product in the moderately near future.

To do nanosecond pulses really needs a product designed specifically for
that kind of speed and the smoothing/linearisation becomes irrelevant.
At those speeds, one changes from linear control to packets of energy.
I'd like to better understand what the constraints, limits and future
potentials are in the technique. There are some physics constraints at
present on the intensity levels that are feasible with LEDs, which might
leave the technique in the realm of lasers for a while.

Thanks for the feedback.

Kind regards,
                  Gordon.

 --
 Gordon Scott  Design Engineering
            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
            CoolLED                    http://www.coolled.com
            CoolLED is a division of Custom Interconnect Ltd.
            Phone [phone]
            CIL House, Charlton Road, Andover SP10 3JL, UK
 
 


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[Gordon Scott]

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Hi Craig,

> -----Original Message-----

> Yeah, the bottom line is as long as your 'flicker' is not
> visible within the time-frame of acquisition you should be fine.

Having contacted one of the camera manufacturers to discuss this
further, they're now talking of cameras possibly to 10k fps, by which
time the ripple would be significant. It's still only a few percent
though, so it may be feasible to compensate. I'm not yet really sure how
realistic that speed is, though. The cameras are only so sensitive and
that speed normally needs a lot of light.

> Regarding the power supply comments, shouldn't it be possible
> to build a sufficiently stable current source for the LEDs?

Our present units are clean and stable. I was looking to see if there
was a slightly less-clean trade-off that I could use to reduce waste
heat. At present I preregulate digitally and then final regulate
linearly, but that costs heat and it's heat I then have to get rid of.
It's much less heat than from a bulb, but then I can't possibly run at
hundreds of degrees temperature like they do.

> Of course I suppose for a commercial product you want to keep
> the costs down.

Always good, provided it doesn't compromise the product :-)

>  Some data acquisition gear I've seen runs
> off dual rechargeable batteries.  They produce pure DC so no
> ripple, and while one battery runs the equipment the other
> charges off wall current.  They switch off as necessary to
> keep the gear running.  Again though this may be
> unnecessarily complex if the ripple proves not to be a problem.

In the LED context a very small ripple at a high frequency is clearly
tolerable. It's really whether I can increase that ripple without it
becoming intolerable.

Kind regards,
                  Gordon.
 --
 Gordon Scott  Design Engineering
            Custom Interconnect Ltd.   http://www.cil-uk.co.uk
            CoolLED                    http://www.coolled.com
            CoolLED is a division of Custom Interconnect Ltd.
            Phone [phone]
            CIL House, Charlton Road, Andover SP10 3JL, UK
 


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[James Pawley]

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>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>Prior to Dr. Hell's excellent 2007 paper cited
>below using laser light pulses in the ns range,
>Dr. Nishigaki et al, in 2006 used the LED
>approach successfully, though with more modest
>gains.  They custom built a pulsed diode with
>broader duty cycle (0.5 to 2ms) that reduced
>bleaching of organic dyes and associated cell
>toxicity.   Apparently driving diodes much
>faster than this raises heating concerns.
>
>Or is this no longer true?
>
>Stroboscopic illumination using light-emitting
>diodes reduces phototoxicity in fluorescence
>cell imaging.  Nishigaki T, Wood CD, Shiba K,
>Baba SA, Darszon A. Biotechniques. 2006
>Aug;41(2):191-7.
>
>Mike Ignatius
>Molecular Probes, Life Technologies

Hi Mike,

Actually, I have some reservations about your
interpretation of this paper. I am not sure that
was a fair fight. First of all, according to the
authors, the Hg arc used for continuous
illumination was originally designed for UV
uncaging. This means that, except for the
excitation filter and the dichroic BS, the optics
were capable of conveying UV to the specimen". I
would have liked to see a UV absorbing filter in
there somewhere just to be sure. Hg produces a
lot of UV and it can reflect around (or even
through) filter systems that aren't properly
designed.

More to the point, as I understand it, the LED
was only on during 1ms of the 2ms that the CCD
camera was recording the image at a rate of 10
images/second (i.e., for only 1% of each second
of recording time). The Hg source seems to have
been on for the full 7 minutes even though the
camera was still on for only the same 10, 2ms
exposures per second. Quote:

The difference between the two samples is
therefore most likely due to the 100- fold
increase in overall exposure time to illumination
light from the mercury lamp (images/s = 10;
duration of individual LED pulse = 1 ms;
therefore total exposure to LED illumination/s =
10 ms, compared with full 1000 ms exposure to
mercury lamp).

In the Discussion, the authors mention that one
might expect improvements if one used the
mechanical shutter on the Hg source to turn off
the excitation except during the 20ms/second when
the the camera was recording but that they hadn't
done so to reduce vibration of the system and
wear-and-tear on the shutter.

I agree. If you use 100x more light, you will do
more damage. I don't think that pulse-length was
important. What was important was duty cycle. In
the LED case, they "used" all (ok, not all, but
all they could collect) of the light that they
excited. In the Hg case they didn't.

In other quibbles, they didn't attempt to measure
the number of mW.s or excitation light at the
specimen from the two sources but assumed that
they must be similar if they produced a similar
level of exposure in their camera, given a fixed
2ms exposure. While this may be convenient and
probably true, we can all think of a number of
factors that may have made this assumption unsafe.

But not unsafe on the same order as a 100x change in total light dose.

So I think that this paper just restates what we
have known for some time (certainly as far back
as the time that time-lapse was recorded on 16mm
film), namely that it is better to turn off the
light when we aren't recording the image. And in
addition, that if your object is moving so fast
that you must record 10 frames/s, the easiest way
to do this is with an LED source rather than a Hg
arc plus an Ultrablitz mechanical shutter (On the
other hand, a suitably synchronized rotary
shutter might do fine.).

Cheers,

Jim P.


*********************************************************************************
Prof. James B. Pawley,                          Ph.  608-263-3147
Room 223, Zoology Research
Building,                          FAX
608-265-5315
1117 Johnson Ave., Madison, WI, 53706  
[hidden email]
3D Microscopy of Living Cells Course, June 11-23, 2011, UBC, Vancouver Canada
Info: http://www.3dcourse.ubc.ca/ 
Applications still being accepted
               "If it ain't diffraction, it must be statistics." Anon.

>
>-----Original Message-----
>From: Confocal Microscopy List
>[mailto:[hidden email]] On
>Behalf Of Jeremy Adler
>Sent: Tuesday, November 30, 2010 7:27 AM
>To: [hidden email]
>Subject: Re: Guidance wanted on illumination stability
>
>*****
>To join, leave or search the confocal microscopy listserv, go to:
>http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>*****
>
>It might also be useful to have pulsatile LEDs operating in the
>nanosecond range - there was a Stefan Hell paper that showed very
>significant reductions in photobleaching when the gap between pulses
>was longer than the fluorescent lifetime. Is this possible with LEDs ?
>
>
>Quoting Gordon Scott <[hidden email]>:
>
>>  *****
>>  To join, leave or search the confocal microscopy listserv, go to:
>>  http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>  *****
>>
>>  Hi Guy,
>>
>>  No the copy strategy didn't work. Of course one only finds that out
>>  after the event. Ho Hum. :-(
>>
>>  My original thoughts on video were as yours, however I _think_ most
>>  cameras take a full image and then the lines are downloaded
>>  sequentially, but I'm also very aware that that may not be the whole, or
>>  even the correct story. If the line rate _is_ important, and I guess if
>>  the data is downloaded from the camera `live' line-by-line, rather than
>>  as a complete image, then 100kHz will definitely show artefacts and the
>>  case is closed .. I need to keep the linear control.
>>
>>  The main aim is actually to avoid unnecessary waste heat, though saving
>>  money is always nice. I'm not sure it would make a particularly
>>  significant effect on price, but it may. Any waste heat I have I then
>>  have to get rid of.  LEDs must not get as hot as bulbs and indeed we
>>  actively cool them to get the best out of them, so getting the excess
>>  heat out of the boxes needs heat sinks and fans or similar. At present
>>  that waste heat puts a frustrating limit on what's feasible with the
>>  units, and I'd like to remove that frustration.
>>
>>  Thanks for your comments.
>>
>>  Kind regards,
>>  Gordon.
>  >  --
>>   Gordon Scott  Design Engineering
>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>    CoolLED                    http://www.coolled.com
>>    CoolLED is a division of Custom Interconnect Ltd.
>>    Phone [phone]
>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>
>>
>>>  -----Original Message-----
>>>  From: Guy Cox [mailto:[hidden email]]
>>>  Sent: 29 November 2010 23:15
>>>  To: Confocal Microscopy List
>>>  Cc: Gordon Scott
>>>  Subject: RE: Guidance wanted on illumination stability
>>>
>>>  Gordon,
>>>
>>>             Your strategy of copying to the list didn't seem to work.
>>>  Anyway, I think that lots of list members, having seen the
>>>  question, like to see the answers.
>>>
>>>             If someone is taking conventional images with a 1
>>>  second exposure 100kHz ripple will not be noticeable.  But if
>>>  you are taking video at 25 fps 525 line (international video)
>>>  your line rate is about
>>>  13 kHz (US video about 14kHz) so I'd imagine there would be
>>>  rather unwelcome diagonal stripes on the image and you'd be
>>>  getting angry phone calls from your customers.
>>>
>>> You haven't told us the other side of the
>>>  trade-off.  Do you want to eliminate the linear stage to save
>>>  money - if so, how much cheaper would it make a CooLED
>>>  illuminator?  Or is it to save power?
>>>  How much would that save?  Given that an LED source already
>>>  uses hugely less power that an HBO 100 mercury lamp, would
>>>  anyone care?
>>>
>>>                                              Guy
>>>
>>>  Optical Imaging Techniques in Cell Biology
>>>  by Guy Cox    CRC Press / Taylor & Francis
>>>       http://www.guycox.com/optical.htm
>>>  ______________________________________________
>>>  Associate Professor Guy Cox, MA, DPhil(Oxon) Australian
>>>  Centre for Microscopy & Microanalysis, Madsen Building F09,
>  >> University of Sydney, NSW 2006
>>>
>>>  Phone [phone]     Fax [phone]
>>>               Mobile [phone]
>>>  ______________________________________________
>>>        http://www.guycox.net
>>>
>>>
>>>  -----Original Message-----
>>>  From: Confocal Microscopy List
>>>  [mailto:[hidden email]]
>>>  On Behalf Of Gordon Scott
>>>  Sent: Tuesday, 30 November 2010 2:34 AM
>>>  To: [hidden email]
>>>  Subject: Guidance wanted on illumination stability
>>>
>>>  *****
>>>  To join, leave or search the confocal microscopy listserv, go to:
>>>  http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>>>  *****
>>>
>>>  Hi Guys,
>>>
>>>  I'm looking at ways to further improve the performance and
>>>  efficiency of our light sources.
>>>
>>>  There are always tradeoffs when doing this and I'd like to
>>>  better understand what tradeoffs are acceptable for real
>>>  microscopy users.
>>>
>>>  Our present illumination sources all use a switched-mode
>>>  pre-regulation and a linear final regulation for the LED
>>>  power, so ripple is very low, but at a cost for us of some
>>>  power wasted in the linear stages.
>>>
>>>  I can improve that efficiency and reduce the waste by
>>>  foregoing the linear stage and regulating directly with the
>>>  switching mode, but the tradeoffs are a longer On/Off
>>>  switching time than is feasible with linear, and a
>>>  high-frequency ripple.
>>>
>>>  My simulations suggest switch-on and switch-off times of
>>>  around 50us and a ripple of around 25% at 100kHz, which would
>>>  be reasonable from an electrical/energy point of view.
>>>
>>>
>>>
>>>  The question is, of course, would any of the people likely to
>>>  use it find that performance difficult or unacceptable?
>>>
>>>
>>>
>>>  I've copied to the list rather than posting direct, so
>>>  hopefully the replies will come to me rather than cluttering the list.
>>>
>>>  Thanks for considering the question, even if you need not, or
>>>  choose not, to answer.
>>>
>>>  Kind regards,
>>> Gordon.
>>>   --
>>>   Gordon Scott  Design Engineering
>>>    Custom Interconnect Ltd.   http://www.cil-uk.co.uk
>>>    CoolLED                    http://www.coolled.com
>>>    CoolLED is a division of Custom Interconnect Ltd.
>>>    Phone [phone]
>>>    CIL House, Charlton Road, Andover SP10 3JL, UK
>>>
>  >>
>>>  This message has been scanned by MailController -
>>>  www.MailController.altohiway.com
>>>
>>>  This message and any attachments are strictly confidential
>>>  and intended solely for the addressee. Any unauthorized use
>>>  or disclosure, in whole or in part, is prohibited. E-mails
>>>  are subject to possible alteration.
>>>  Custom Interconnect Ltd and the sender decline any liability
>>>  if this message and/or any attachments have been altered,
>>>  changed or falsified.
>>>  If you are not the intended recipient of this message, please
>>>  delete it and notify the sender immediately.
>>>
>>>  Custom Interconnect Limited is a limited company registered
>>>  in England and Wales. Registered number: 2026753. Registered
>>>  office: CIL House 48 Charlton road Andover, Hampshire United
>>>  Kingdom SP103JL.
>>>
>>
>
>
>
>Jeremy Adler
>Genetics & Pathology
>Rudbeckslaboratoriet
>Daghammersköljdsväg 20
>751 85 Uppsala
>Sweden
>
>0046 (0)18 471 4607

--
*********************************************************************************
Prof. James B. Pawley,                          Ph.  608-263-3147
Room 223, Zoology Research
Building,                          FAX
608-265-5315
1117 Johnson Ave., Madison, WI, 53706  
[hidden email]
3D Microscopy of Living Cells Course, June 11-23, 2011, UBC, Vancouver Canada
Info: http://www.3dcourse.ubc.ca/ 
Applications still being accepted
               "If it ain't diffraction, it must be statistics." Anon.

[Clements, Ian]

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Hi Mike

We, and our customers, are finding it increasingly difficult to find 100 nm beads in a variety of colors.  In particular we are getting stuck for AF647/Cy5 range beads.  No one has anything that is a good match in this range.

I don't want to waste my time talking to Life Tech about a custom job as it's a joke but is there anything in the pipeline.  With the advent of super resolution systems the PS-Speck beads are now too large for this purpose and the 40 nm beads not bright enough.

Ian Clements
Product Manager - DeltaVision OMX Systems

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[Clements, Ian]

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Apologies to group for mis-directed message but happy to hear from anyone who has a source of these.

Ian


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[Andreas Bruckbauer]

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 What about 0.1 micrometer TetraSpeck beads from Molecular Probes? They are about 110 +/- 6 nm in size (might depend on the batch) and light up in all channels inclusive the far red. However they seem to loose their fluorescence over time and are useless after a month or so.

best wishes

Andreas

 


 

 

-----Original Message-----
From: Clements, Ian <[hidden email]>
To: [hidden email]
Sent: Thu, 2 Dec 2010 21:56
Subject: Re: 100 nm PSF kit


*****

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Apologies to group for mis-directed message but happy to hear from anyone who

has a source of these.



Ian





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Inc. If you are not the intended recipient, your review, use, disclosure,

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information contained therein, is strictly prohibited. If you are not the

intended recipient or if you think this email was sent to you in error, please

notify the sender by reply email and delete this message and its attachments, as

well as all copies, from your system.





This email message, together with any attachments, is for the sole use of the

intended recipient(s) and is the confidential information of Applied Precision

Inc. If you are not the intended recipient, your review, use, disclosure,

copying or dissemination of this email message or its attachments, or the

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notify the sender by reply email and delete this message and its attachments, as

well as all copies, from your system.


 

[Grace Chojnowski]

G'Day Ian, have your tried Polysciences? I know they have a good range of beads..

Kind Regards,
Grace

 Grace Chojnowski
 Flow Cytometry and Confocal Microscopy Laboratory Manager
 Queensland Institute of Medical Research
 Brisbane, QLD, AUSTRALIA
  [hidden email]
  [phone].     6+61 414 956 752
 [phone]
 http://www.qimr.edu.au/flow


-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Clements, Ian
Sent: Friday, 3 December 2010 7:52 AM
To: [hidden email]
Subject: 100 nm PSF kit

*****
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Hi Mike

We, and our customers, are finding it increasingly difficult to find 100 nm beads in a variety of colors.  In particular we are getting stuck for AF647/Cy5 range beads.  No one has anything that is a good match in this range.

I don't want to waste my time talking to Life Tech about a custom job as it's a joke but is there anything in the pipeline.  With the advent of super resolution systems the PS-Speck beads are now too large for this purpose and the 40 nm beads not bright enough.

Ian Clements
Product Manager - DeltaVision OMX Systems

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[Clements, Ian]

As I recall they also own Bangs now but will check them out.

Ian Clements
Product Manager - DeltaVision OMX Systems


-----Original Message-----
From: Grace Chojnowski [mailto:[hidden email]]
Sent: Thursday, December 02, 2010 2:18 PM
To: [hidden email]
Subject: Re: 100 nm PSF kit

G'Day Ian, have your tried Polysciences? I know they have a good range of beads..

Kind Regards,
Grace

 Grace Chojnowski
 Flow Cytometry and Confocal Microscopy Laboratory Manager
 Queensland Institute of Medical Research
 Brisbane, QLD, AUSTRALIA
  [hidden email]
  [phone].     6+61 414 956 752
 [phone]
 http://www.qimr.edu.au/flow


-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Clements, Ian
Sent: Friday, 3 December 2010 7:52 AM
To: [hidden email]
Subject: 100 nm PSF kit

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Hi Mike

We, and our customers, are finding it increasingly difficult to find 100 nm beads in a variety of colors.  In particular we are getting stuck for AF647/Cy5 range beads.  No one has anything that is a good match in this range.

I don't want to waste my time talking to Life Tech about a custom job as it's a joke but is there anything in the pipeline.  With the advent of super resolution systems the PS-Speck beads are now too large for this purpose and the 40 nm beads not bright enough.

Ian Clements
Product Manager - DeltaVision OMX Systems

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[Clements, Ian]

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We do use these but for certain applications we need single color beads.  Also the TetraSpecks are not quite as bright but it may be all we can do right now.

Ian Clements
Product Manager - DeltaVision OMX Systems


-----Original Message-----
From: Andreas Bruckbauer [mailto:[hidden email]]
Sent: Thursday, December 02, 2010 2:10 PM
To: [hidden email]
Subject: Re: 100 nm PSF kit

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 What about 0.1 micrometer TetraSpeck beads from Molecular Probes? They are about 110 +/- 6 nm in size (might depend on the batch) and light up in all channels inclusive the far red. However they seem to loose their fluorescence over time and are useless after a month or so.

best wishes

Andreas








-----Original Message-----
From: Clements, Ian <[hidden email]>
To: [hidden email]
Sent: Thu, 2 Dec 2010 21:56
Subject: Re: 100 nm PSF kit


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Apologies to group for mis-directed message but happy to hear from anyone who

has a source of these.



Ian





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[Guy Cox-2]

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The funny thing is that Bangs list, in their spectra, "Far out red"
which seems to be exactly the colour you want - but they don't seem to
offer many (any?) actual beads with this dye.

                                    Guy

Optical Imaging Techniques in Cell Biology
by Guy Cox    CRC Press / Taylor & Francis
     http://www.guycox.com/optical.htm
______________________________________________
Associate Professor Guy Cox, MA, DPhil(Oxon)
Australian Centre for Microscopy & Microanalysis,
Madsen Building F09, University of Sydney, NSW 2006

Phone [phone]     Fax [phone]
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-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]]
On Behalf Of Clements, Ian
Sent: Friday, 3 December 2010 10:27 AM
To: [hidden email]
Subject: Re: 100 nm PSF kit

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We do use these but for certain applications we need single color beads.
Also the TetraSpecks are not quite as bright but it may be all we can do
right now.

Ian Clements
Product Manager - DeltaVision OMX Systems


-----Original Message-----
From: Andreas Bruckbauer [mailto:[hidden email]]
Sent: Thursday, December 02, 2010 2:10 PM
To: [hidden email]
Subject: Re: 100 nm PSF kit

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


 What about 0.1 micrometer TetraSpeck beads from Molecular Probes? They
are about 110 +/- 6 nm in size (might depend on the batch) and light up
in all channels inclusive the far red. However they seem to loose their
fluorescence over time and are useless after a month or so.

best wishes

Andreas








-----Original Message-----
From: Clements, Ian <[hidden email]>
To: [hidden email]
Sent: Thu, 2 Dec 2010 21:56
Subject: Re: 100 nm PSF kit


*****

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http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy

*****



Apologies to group for mis-directed message but happy to hear from
anyone who

has a source of these.



Ian





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of the

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Precision

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please

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attachments, as

well as all copies, from your system.





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Precision

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the

information contained therein, is strictly prohibited. If you are not
the

intended recipient or if you think this email was sent to you in error,
please

notify the sender by reply email and delete this message and its
attachments, as

well as all copies, from your system.





This email message, together with any attachments, is for the sole use
of the intended recipient(s) and is the confidential information of
Applied Precision Inc. If you are not the intended recipient, your
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or its attachments, or the information contained therein, is strictly
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