FP-1 Floor Platforms for SEMs, TEMs and *STEMs
Floor platforms designed
to isolate low-frequency vibrations from SEMs and TEMs
The FP-1 consists of a large platform, two or three Minus
K® SM-1 negative-stiffness vibration isolators, outriggers
which connect the platform to the isolators, isolator floor
and jack screw plates which help to spread the load on the
floor and ballast weights.
The FP-1 platform is a heavy steel plate which typically
weighs nearly as much as the microscope itself. One reason
for this design is to lower the overall system center of gravity
to the level of the isolator tilt mechanism, so as to avoid
horizontal-tilt coupling, which occurs when horizontal vibrations
cause both a horizontal and tilting response of the column.
With the system CG at the level of the isolator tilt mechanism,
the vibrations are decoupled and better isolation control
is achieved. Another reason for the massive platform is that
the large total mass of the system helps to diminish any effects
from stiff cables and hoses connected to the microscope.
LEO 1550 SEM on a two-isolator floor platform
|
Hitachi S-4800 SEM on a three-isolator
floor platform
For SEMs and some TEMs only the column console is isolated.
In some cases the column, display and other components are
isolated on the platform.
The system can achieve natural frequencies of
0.5 Hz or less, vertical and horizontal, with all external
line, hoses and cables disconnected from the isolated payload
and the internal isolators locked out. (with most microscopes
the external lines, hoses and cables have a relatively small
effect on the isolation system performance).
Customers that prefer to make the platform themselves can
purchase the design, the SM-1 Minus K negative-stiffness vibration
isolators and build the platform locally to save fabrication
and shipping costs.
|
