Craig Brideau <[log in to unmask]> writes:

> could see no noise from the earthquake in his readings!  This is a
> severe case of course, and usually the problem is some strange motor
> vibration or the like that sneaks in to the system because it happens
> to match a resonant frequency of the system.  This is why a low
> frequency response is good; it is less likely to find a match in the
> surrounding environment.

Optical microscope systems also tend to be very stiff at low frequencies
and so you don't have to worry about them too much. The higher
frequencies cause the problems but they are very effectively damped by a
decent vibration isolation table.

Ian