Posted by
Keith Morris on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Cotton-wool-for-lens-cleaning-tp6175236p6180861.html
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Hi Michael,
The cement holding the top lens is easily damaged - small fissures develop
and the oil creeps behind the lens where it can't removed. You used to able
to send the objectives away to Zeiss for 'repair', but now that seems to
cost more than the objective. Our Zeiss 510 confocal 40x plan neofluar
apparently has some oil ingress but the image focuses adequately through it
[can't tell any difference really at that lower mag] - many probably carry
on not knowing it's happened [we mainly use the 63x Plan Apochromat for high
detail work anyway]. We lost one 20x air objective to cross contamination
oil ingress, and image quality was affected very badly in that case - I
expect the objective was previously damaged by impact. One microscopy core
manager did comment to me that he considers oil objectives a disposable item
as they can be damaged in a very busy multi-user facility. This problem is
probably more acute in cores like us where live cell is used and all
microscopes are in inverted configuration - with an upright the oil drops
off rather than in - although surface tension will draw the oil past the
cement if the cement does develop fissures. Inverted microscopes also suffer
far more from users crashing the objective into the stage etc.. [as you
can't see them too easily].
Regards
Keith
---------------------------------------------------------------------------
Dr Keith J. Morris,
Molecular Cytogenetics and Microscopy Core,
Laboratory 00/069 and 00/070,
The Wellcome Trust Centre for Human Genetics,
Roosevelt Drive,
Oxford OX3 7BN,
United Kingdom.
Telephone: +44 (0)1865 287568
Email:
[hidden email]
Web-pages:
http://www.well.ox.ac.uk/molecular-cytogenetics-and-microscopy-----Original Message-----
From: Confocal Microscopy List [mailto:
[hidden email]] On
Behalf Of Cammer, Michael
Sent: 17 March 2011 12:41
To:
[hidden email]
Subject: Re: Cotton wool for lens cleaning
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I don't think there really is one general solvent. When I began doing
biological microscopy about 20 years ago the immersion oils all seemed to be
made of the same stuff and easily cleaned with just about any organic
solvent stronger than ethanol. This is no longer the case. For instance,
the new Nikon oil for TIRF gets thick and is completely impervious to any of
the aqueous cleaners. It is resistant to what we practically considered to
be the universal solvent of organics, acetone, and also to ethanol. But
dehydrated methanol works great. On the other hand, the Zeiss oils, when
fresh, clean up fine with their aqueous cleaning solutions and when old and
dripped all over the turret and such, with acetone. The old standby in the
lab, Cargill Labs type DF, cleans up with any inorganic solvent. Of course,
in one lab the gospel was xylene because, well, we scientists tend to be
superstitious or traditional. As for ether, one benefit of using it, we
were told years ago by someone at Zeiss, is that it evaporates so fast that
it reduces the chances of dissolving the glue holding in the front glass of
the objective. Is this really a problem? I've never had one of these front
lenses come loose. Now I tend to use 1:1 acetone/methanol and cotton swabs
and/or lens tissue following in the footsteps of Spectraphysics service who
uses this to clean their mirrors and gives us average power of a Watt with
100 fs pulses at 910-920 nm, so I follow by example.
-Michael Cammer
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