Breadboards and Optical Table Tops

All LINOS Photonics optical table tops are of unique design. Our consistent use of all theoretical principles resulting in superior stiffness and optimized internal damping has led to their being ranked among the best optical table tops commercially available.

Major features include:

• small cell, steel-honeycomb cores
• steel top/bottom plates and sidewalls
• threaded holes tapped directly into their top plates
• patented "Clean-Top II" sealing of all tapped holes
• hybrid, integral, damping mechanisms
• high-strength, non-aging, epoxied joints
• broad range of standard models
• custom-built models available custom dimensions alternative structural materials custom tapped-hole grids/threads access ports and/or cutaway sections OEM-versions

Design Features

All of our optical tables are laminated structures con-sisting of steel top and bottom plates bonded under high pressure, by two lapped granite plates, to steel-honey-comb cores using a special epoxy resin. Their sidewalls are fabricated from steel plates, and seam-welded to other structural elements to form rigid structural units. All table tops are equipped with specially tuned, inter-nally mounted, damping mechanisms, such as damping mats laminated onto the inner surfaces of their sidewalls and damping masses installed at strategically chosen internal points. Their broadband characteristics make them equally effective at all frequencies.

Our "Clean-Top" option seals the bottoms of tapped holes in table tops with special tubular caps that prevent liquids that might attack bonding adhesives from entering the interiors of table tops.

Steel-honeycomb Cores

Our steel-honeycomb cores are fabricated from 0.25 mm gauge corrosion-resistant coated sheet steel. The small diameters of the tubular caps used on table tops equipped with our Clean-Top option have allowed us to reduce honeycomb-cell cross-sectional area to 3 cm2. The resulting high cell density yields extremely stiff table-top structures. This high cell density also provides large contact areas for bonding top and bottom plates to honeycomb cores, making table tops even stiffer. Our honeycomb cores incorporate even smaller cell cross-sections at strategic points, which increases their average mass density to 0.27 g/cm3. This type of honeycomb-core design has a shear modulus of 1.9x109 N/m2.

Top Plates

Top plates are fabricated from cold-rolled ferromagnetic stainless steel, and directly bonded to honeycomb cores by a bonding process that leaves them unstressed. Top plates are available in thicknesses of 3 mm or 5 mm, and are flat to within +/- 0.13 mm over the entire surface. The upper surfaces are ground to reduce disturbing reflections.

Bottom Plates

Bottom plates are bonded to honeycomb cores using the same process used for bonding top plates, and are also left unstressed. Bottom plates are fabricated from cold-rolled steel and coated with black epoxy paint. The unique, direct core-to-top bonding improves the thermal conductivity of the core to the outside environment, reducing the "thermal relaxation time" for the top. Bot-tom plates have the same thickness as top plates.

Sidewalls

Sidewalls are fabricated from 1.9 mm gauge cold-rolled steel in order to provide even greater stiffness, even better structural integrities, and the structural uniformity needed to preclude thermal distortions, even under large temperature excursions. Sidewalls are seam-wel-ded along all edges, and have damping mats applied to their inner surfaces. Their outer surfaces are coated with fiber-reinforced, grained, vinyl. Stainless-steel guards protect all corners. The plastic coatings on their outer surfaces make sidewalls highly resistant to dampness and moisture. Sidewall plates may be drilled and tapped for attaching various types of hardware.

Tapped-hole Grids

All threads are cut into through-holes in table top plates using high-precision taps. These accurately cut, smoothly finished, threads provide the easy, manual, insertion of threaded fasteners needed for rapid assembly of optical experiments. Unlike threaded inserts or bushings, tapped holes withstand both tensile and compressive loads. The heavy-gauge, high-strength, stock we use for our table top plates will support even heavy objects without buckling. All tapped holes have chamfered rims in order to preclude personal injuries.

All table tops are available with tapped holes spaced on 25 mm centers.

Radius Corners

LINOS Photonics tops now include a user-friendly 25 mm radius corner as a standard feature. These radius corners are especially appreciated in darkened rooms to avoid painful pushes.

Clean Top II Equipment

The new Clean Top II optical top equipment is the best method to protect the honeycomb core from outer flowing in, e.g. agressive fluids. Its design involved capacitance discharge welding a 25 mm long stainless steel or plated steel cup under each drilled hole prior to thread tapping. Cups are epoxy-bonded and made from nylon-6, and stainless steel (optional). Clean Top II cups are small and cylindrical, this allows a high core density and therefore assures highest stability of the honeycomb core.

Chemical resistance of nylon 6 and stainless steel:

                                                  Nylon 6           Stainless    
                                                                         Steel
Aromatic solvents                      excellent         excellent
Aliphatic solvents                       excellent         excellent
Hydrocarbons                            excellent         excellent
Gasoline and oils                       excellent         excellent
Refrigerants                              excellent         excellent            

Chlorinated solvents                   good              excellent
Weak acids                                good              excellent
Strong acids                               attacked         excellent
Weak alcalines                          excellent         excellent
Strong alcalines                         good              excellent
Oxidizing agents                       attacked         excellent

Strong Internal Damping

Table tops exhibit strong internal damping that both minimizes their response to external shocks and vibra-tions and dissipates the energies of any activated vibrational modes of their top plates. The internal dam-ping characteristics of table tops are particularly critical in cases where they are supported on vibration-isolation systems.

Many manufacturers use viscoelastic adhesives to attach top and bottom plates to honeycomb cores, a practice that substantially reduces the stiffnesses of final table-top structures. All epoxy resins used by LINOS Photonics are hard-setting and supplemented by damping masses. This approach eliminates both aging effect and outgassing. The damping characteristics of our table tops are individually tuned to their structural resonances.

LINOS Photonics's firm adherence to these design prin-ciples in manufacturing its optical table tops results in superior-quality table tops exhibiting stiffness that has yet to be equalled. Their low compliances, the recipro-cals of their dynamic rigidities, are readily evident from their corner-compliance curves.

Dry Damping

The damping of the optical table tops is based on a system of broadband dry damping, which damps all existing resonances. Dry damping is preferable to oil-based dampers. Oil's characteristics can change over time and hidden oil reservoirs are always in danger of being pierced by an end-user customizing his system.

An optical top's resonant frequency will vary based on load, distribution of load, temperature, and even the presence of the dampers themselves. Therefore, in practice, it is difficult to tune the dampers to the top's resonance. The broadband damping technique is therefore the most effective way to damp an optical top.

LINOS Photonics offers three levels of damping:

Maximum damping:

For holography, interferometry, spectroskopy, also recommended in particularly noisy vibration and for puldes lasers.

Standard damping:

For less sensitive applications. This broadband damping level provides a top with performance characteristics that exceed the majority of other manufacturers' highest performance levels.

Nominal damping:

For general lab work when the main consideration is a rigid, flat mounting surface.

We present on the left side the corner-compliance curves for the three damping levels. In this example a table with the dimensions 1200x2400x300 mm is used. To convert from in/lb to mm/N multiply by a factor of 5.7.

Example: 10-6 in/lb x 5.7 = 5.7 x 10-6 mm/N.