>THE PROBLEM:
>We study living cells and have some problems with temperature
>controlling. It seems that a variation of less than 0.1 degree C
>influences the
>focal depth too much. The focal depth changes sometimes 0.5 um.
>
>THE SET-UP:
>  1) 60x/1.4 Nikon (on a Biorad MRC 1000/1024)
>  2) an objective heater and its controller.
>  3) cells on a Glass Bottom Petri dish (MatTek)
>  4) a 'warm table' for the petri-dish and its controller
>
>The heater controllers keep the temperature on 37 C with an accuracy
>of less that 0.1 C so, that seems to be good enough.
>
>THE QUESTION:
>  1) Has anyone similar problems?

Yes, I did.
>  2) Did anyone solve the problem?

The problem is most likely thermal expansion/contraction in the
microscope stand itself. Remember there is quite a bit of
non-temeperature-controlled metal between the points where your lens and
your table are fixed respectively. I solved my problem by building a
temperature controlled, front-accessible airflow box that keeps the WHOLE
microscope at a constant temperature.

blu





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Dr. Beat Ludin, FMI, PO Box 2543, 4002 Basel, Switzerland
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