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Dear Nic,
Our system indeed is a 3i-spinning disk as well and we actually narrowed it down to the same origin as you did: the heater of the incubation chamber.
We contacted Okolab yesterday and they are very helpful in helping us to find a solution for our problem.
We will try to change some things in the setup and restore the default parameters of the thermal controller. We hope this will help.
Cheers,
Oliver
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Oliver Biehlmaier, PhD
Head of Imaging Core Facility
Biozentrum (Kragenbau, Room G1054)
University of Basel
Klingelbergstrasse 50/70
4056 Basel
Switzerland
Office: +41 (61) 267 20 73
Lab: +41 (61) 267 22 50
Email: [log in to unmask]
http://www.biozentrum.unibas.ch/imcf
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Am 22.08.2013 um 19:01 schrieb Nic Cade:
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> *****
>
> Hi Niko,
>
> Which microscope system do you have this problem with? Do you also see a
> corresponding change in focus?
>
> We have a very similar problem with our 3i spinning disk system where we see a
> periodic oscillation in lateral position, ~250nm every 60s. We think we have
> narrowed it down to the heater for the incubation chamber (Okolab) which also
> switches on and off with a period of 60s. Another group here with the same
> system have found exactly the same thing; turning off the heater stopped the
> oscillations.
> I'm guessing that in your case the oscillations might be large enough to move
> your sample through the focal plane, but which wouldn't affect any featureless
> background. You could test this with some fluorescent beads if you haven't
> done so already.
>
> Cheers
> Nic
>
> On Fri, 16 Aug 2013 17:37:32 +0200, Niko Ehrenfeuchter
> <[log in to unmask]> wrote:
>
>> *****
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>>
>> Dear all,
>>
>> we're recently facing a very strange behavior on one of our spinning
>> disk systems. One of our users noticed a repeated fluctuation in
>> recorded timelapse experiments (this was a FRAP experiment, but we don't
>> think that's related to FRAP).
>>
>> The timelapse was recorded every 6 seconds, and after background
>> subtraction a repeating drop of signal is visible in the intensity plot
>> (please find the corresponding graph under [1], see below). The
>> fluctuation is also visible by eye when scrolling through the timelapse.
>>
>> We noticed a frequency of 66 seconds and therefore think we can exclude
>> any external vibrations as source of this problem (plus the system is
>> mounted on a Melles Griot optical table). On some experiments the
>> oscillation almost follows a sine-like function, on others (like the
>> mentioned one) it looks more rectangular with a very rapid drop and
>> raise. Also, the frequency does *not* change if we double the
>> acquisition frequency, it's still on 66 seconds when acquiring every 3
>> seconds.
>>
>> One very weird thing is the stability of the background. The plots from
>> above show the intensity in selected ROI's over cells. The same plot for
>> an "empty" region in the sample shows a more or less constant signal (at
>> least we could figure a pattern in it, even after normalization and
>> using a big scaling factor to visualize the deltas).
>>
>> Has anyone of you come across a similar behavior?
>>
>> Any ideas about this would be highly appreciated!
>>
>> Many Thanks,
>> Niko
>>
>> [1]
>> https://www.biozentrum.unibas.ch/fileadmin/redaktion/Forschung/Research_Gr
> oups/IMCF/3i_intensity_fluctuation.png
>>
>> --
>> Niko Ehrenfeuchter
>> Imaging Core Facility
>> Kragenbau, Room G1055
>> Biozentrum, University of Basel
>> Klingelbergstrasse 50/70
>> CH-4056 Basel (Switzerland)
>>
>> Office: +41 (61) 26 72673
>> Email: [log in to unmask]
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