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Hi Olaf: Many materials have coefficient of thermal expansion on the 
order of 10^(-5) 1/K. So if your microscope was a solid block and the 
distance between the objective and the stage was 1 cm, then you could 
expect variation on the order of 0.1 micron per degree. I imagine that 
variations in the refractive index of immersion oil with temperature 
may have a greater effect on focusing. 

Michael Model
Confocal Imaging Core,
Department of Biological Sciences,
Kent State University,
Kent, OH 44242
tel. 330-672-2874

----- Original Message -----
From: "Dr. Olaf Selchow" <[log in to unmask]>
Date: Tuesday, November 14, 2006 3:29 pm
Subject: Thermal Focus Drift - Olympus BX 51 WI -
To: [log in to unmask]

> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
> 
> Hello List,
> 
> anybody out there who has an idea about how much focus shift 
> (approximately) I can expect from a 5 (10) deg celsius temperature 
> change in the lab on an Olympus BX 51 WI?
> With aproximately I mean: is it 1, 5 or 10 µm?? Or even more?
> 
> I know I should keep the temperature constant (the goal in our 
> case is 
> plus minus 1 deg C) but we need to know how much the focus shifts 
> to 
> have good arguments to ask for better air conditioning the lab...  
> A 
> measurement would take time - therefore it would help a lot if 
> someone 
> has done the test already and can help out with his experience.
> 
> Thanks very much!
> 
> Olaf
>