http://confocal-microscopy-list.275.s1.nabble.com/Guidance-wanted-on-illumination-stability-tp5784748p5788478.html
was longer than the fluorescent lifetime. Is this possible with LEDs ?
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>
> 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 +44-1264-321321
> 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 +61 2 9351 3176 Fax +61 2 9351 7682
>> Mobile 0413 281 861
>> ______________________________________________
>>
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 +44-1264-321321
>> CIL House, Charlton Road, Andover SP10 3JL, UK
>>
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>