1. Damping
TMC offers three levels of structural damping, though not
all levels are available in each construction. Because the damping
mechanisms are expensive to manufacture, it is prudent to specify only
the level of damping required.
All TMC damping levels incorporate broadband dry damping.
For a complete description of broadband vs. tuned damping, .
Maximum Dry
Damping. TMC’s maximum dry damping provides
a level of performance unsurpassed in the industry. It
is recommended for the most demanding applications including
holography, interferometry, ultra-fast optics, and spectroscopy.
In addition, it is recommended in particularly noisy vibration
and acoustic environments. For pulsed lasers and other
noise generation equipment, it is especially helpful.
Standard Dry Damping.
An economical alternative for less
sensitive applications incorporates our
standard dry damping level. This broadband
damping level provides a top with performance
characteristics that exceed the majority
of other manufacturers’ highest
performance levels. Peak compliance
levels for standard damping exceed peak
compliance levels of our maximum damping
by a factor of four.
Radius Corners
TMC tops now include a user-friendly 1 in. radius
corner as a standard feature at no extra charge. These “hip-savers” are
especially appreciated in darkened rooms. This feature does not impact
overall dimensions or the hole pattern
.
Nominal Dry Damping. This
damping level is not recommended if sensitive work
is being conducted on the table. The nominal damping
level is appropriate for general lab work when the
main consideration is a rigid, flat mounting surface.
Please refer to the Dry Damping Performance Summary
for more information.
2. Skin Thickness
The vast majority of TMC optical tops are available in
a choice of two thicknesses: 3/16 in.
(5 mm) and 1/8 in. (3 mm). For structural performance
reasons, the 3/16 in. thick version is generally recommended. In
addition, since
the top skin includes an array of drilled and tapped
holes, the 3/16 in. version gives nearly four full threads for more
secure mounting.
When cost is an overriding concern, 1/8 in. skins are
an attractive alternative. The
stainless steel top skin is a major cost element in the
top and eliminating 33% of the stainless steel reduces the manufacturing
cost significantly.
A third skin thickness is available
as an option for 2 in. (50 mm) thick breadboards. Patented
techniques allow TMC to form a top skin 0.075 in. (2 mm)
thick, while maintaining a full three threads tapped directly
into the skin. Advantages include low cost and light weight.
3. Overall Top Thickness
A top length-to-thickness ratio of 10:1 is a safe rule
of thumb for most applications, although for very sensitive work in
severe environments, a ratio of 7:1 may be justified. It should also
be kept in mind that while top thickness is proportional to top static
rigidity and dynamic natural frequency, it does not directly affect
compliance, which is primarily controlled by structural damping.
Small, 2 in. (50 mm) thick tops should be supported on
uniform flat surfaces, not post mounts. Our 4 in. (100 mm) thick
tops may be supported on post mounts, but they do not incorporate
the same proprietary damping techniques used on our thicker tops.
We recommend that all sensitive work
be done on tops at least 8 in. (200 mm) thick.
4.
Environment
For most applications, our CleanTop® II optical top is the best
choice.
ClassOne™CleanTop® II:
The ClassOne™ version
takes CleanTop II
one step further. Designed for maximum
cleanroom compatibility, the ClassOne
CleanTop II has not only a stainless
steel top skin but stainless steel sides
and a stainless steel bottom skin as
well. Nylon 6 cleantop cups are standard
and 316 alloy stainless steel cups are
available as an option.
Wiped down with lint-free
cloth, the ClassOne™ is wrapped in plastic prior
to shipping and may be brought directly into a
cleanroom.
Non-Magnetic
CleanTop® II.
For
work in a highly magnetic environment, we now
offer our new non-magnetic construction. This table is
made from 304 alloy stainless steel rather than the conventional
ferromagnetic 430 alloy. Though the skins,
sides, dampers, and core are a 304 alloy, no stainless
steel top can be said to be “100%” non-ferromagnetic.
In some cases, 316L alloy is preferable and custom construction
from this material is available on special
order.
5. Tapped Holes
TMC offers both imperial 1/4 - 20 tapped holes on 1 in.
centers and metric M6 tapped holes on 25 mm centers.
Though there is no price difference between tops, imperial tops have
imperial overall dimensions while metric tops have metric overall dimensions.
In addition, we now offer
both imperial 1/4 - 20 tapped holes on 1 in. staggered centers
and metric M6 on 25 mm staggered centers, doubling the number
of tapped holes on conventional 1 in. or 25 mm girds. The
DoubleDensity™ construction is available with any version
of our CleanTop® II at a nominal additional fee.
For more information, see DoubleDensity™ tops,
