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Micromanipulators and Isolation tables!

Francis Burton fburton at nyx10.nyx.net
Wed Nov 5 07:28:00 EST 2003

In article <4qigqvcm7duvvu8a37ficg7n03kivcceta at 4ax.com>,
r norman  <rsn_ at _comcast.net> wrote:
>Vibration isolators only dampen vibration above a certain cutoff
>frequency.  Then do not "eliminate" it. Low frequency vibrations, in
>particular, are hard to eliminate.

What may help to some extent is a more rigid coupling between
the different mechanical parts. That means mounting the manipulator
on the microscope stage should give less relative movement between
electrode and cell than when the manipulator is mounted on the
table top, say.

>Look at the suface of the water in a wide flat dish, like a petri
>dish.  Do you see vibrations or ripples?  Put the dish on the floor.
>Are they much worse?  (You might be talking about vibrations too small
>to see in the water.  Then again, you might be talking about
>vibrations magnified in the electrode mounting arm).

Do you think resonance might be important here? If the vibration
source has a dominant frequency and parts of the manipulation
system are resonating to that frequency, the problem will be
worse. It might be worth changing some lengths (e.g. of the
mounting arm) to see if that makes a difference.

>In any event, if the floor really is rumbling that bad you are in some
>trouble.  Where are the elevator motors for your building?  the
>building ventilation fan motors?  the hood fan motors?  Do trucks
>rumbling down the street change things?  Depending on the building
>design, all these can be major factors.  Or they can be absolutely

Good point. Are other people working on similar rigs in the same
building? If so, do they also have problems with vibration?

>It's a toss-up which is worse, finding and eliminating vibration or
>finding and eliminating ground loops and line voltage electrical

Been there, done that!


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