Dear All,

     This is a very common problem for all confocals. It's one of the main
     reasons why most manufacturers use optical fibres when they can.

     The major vibration sources are the cooling fan for the laser and the
     computer cooling fan (surprising but very common). A common secondary
     source is the UV lamp supply. It's convenient to sit it on the table
     next to the microscope. Trouble is, it rattles at 50 (60) Hz.

     The laser cooling fan is easily isolated if you cut the exhaust duct
     and then rejoin it with a short section of suitable tubing. Just about
     anything will do, make the section about 20 cm long so it is easy to
     handle.

     The computer should not touch the microscope table. Also, the table
     should not be pressed against or attached to any walls. Ideally, you
     should use an AV table but I know how expensive that can be. I've
     found that the best way to get lousy images is to try fixing the
     microscope bench rigidly to the building it is in. AV table
     manufacturers have known this for years which is why they insist on
     the table being free standing. I've seen a lot of users who have
     beautiful AV tables, properly installed, but don't bother to pump them
     up. Would you do the same to the tyres on your car ??


     One other misconception which I hear a lot involves the use of heavy
     table tops, such as granite to reduce vibration. Sorry, vibration
     doesn't respect that theory at all. The granite will not sustain
     vibrations the way a light table top does, which is good, but it won't
     stop the transmission of vibration to the microscope. Usually, it's
     the mounts upon which the granite sits which are the real workers
     (unsung heroes). So my general advice is to use a solid table top
     which does not flex (this is the main advantage of granite) and some
     good quality AV supports.

     Best Regards
     Allan A.

     Allan Anderson
     [log in to unmask]
     Pacific Technical Manager for Confocal Imaging
     Bio-Rad Pacific.


______________________________ Reply Separator _________________________________
Subject: Re: air-cooled laser vibration
Author:  Confocal Microscopy List <[log in to unmask]> at
Internet
Date:    07/10/98 17:25


Dear Confocalists:

I wonder whether Donna's description of a cooling fan-induced vibration is
a common problem with Zeiss confocal microscopes.  I'm fighting with
similar problems on a LSM 410 which sometimes completely disables high
resolution images.

I heard that a solution may be fans with highly reduced vibration levels.
Can anyone offer additional solutions?

Jacques


>
>Air-cooled laser fans are the source of considerable vibration which can
>compromise your resolution. Our solution for an older Zeiss LSM 310 was to
>remove the laser cooling fan from the manufacturer's housing and suspend it
>close to the original position near the laser through a bracket completely
>isolated from the table upon which the LSM is situated.  Although this
>requires some cutting of holes in housings and covers, installation of
>bracket etc.  it is not a very big job and solved the problem completely.
>No amount of bricks or damping material is going to do the job.
>
>
>Donna Arndt-Jovin
>MPI for Biophysical Chemistry
>Dept. of Molecular Biology
>Am Fassberg
>D-37070 Goettingen, Germany
>tel: +49-551-201-1393
>fax: +49-551-201-1467
>e-mail: [log in to unmask]


---------------------------------------
Dr. Jacques Paysan
Universitaet Tuebingen
Institut fuer Physiologie, Abt. II
Ob dem Himmelreich 7
D-72074 Tuebingen
Germany

Telefon: (07071) 29 771 73
Telefax: (07071) 87 815