Offering protection of an optical table’s inner core from spills, such as water-cooled or liquid-dye lasers, soft drinks, or coffee, is preventative for major contaminations deep in the honeycomb core that can affect the table's stability.
The SPILLPRUF configuration seals whole rows of mounting holes and diverts liquids away from the internal honeycomb core of the table. Tables with individually sealed holes require thorough cleaning of individual holes, while SPILLPRUF offers the ultimate protection by sealing the whole row. This makes cleanup quicker and more efficient, with no need to remove apparatus from the table.
SPILLPRUF Improves the Rigidity of the Table
All-metal construction offers a truss-like reinforced top skin to stiffen the table. KSI uses the same principle to improve the stiffness of aircraft wings. Other designs have used a low-modulus plastic dimpled membrane between the skin and core, resulting in reduced table stiffness. Metal cup designs increase the weight and, by proxy, deflection but do not stiffen the table.
SPILLPRUF Maintains Table Thermal Conductivity
The all-metal construction guarantees rapid heat flow throughout, which eliminates distortion of the tabletop caused by uneven expansion and contraction. Alternate designs that use a plastic membrane under the top skin experience reduced heat transfer and flatness degradation.
Figure 21.1. SPILLPRUF Spill Management System. Image Credit: Kinetic Systems, Inc.
SPILLPRUF™ – A Better Technology for Handling Spills
SPILLPRUF™ is a patented technique that protects the inner core of KSIs honeycomb optical tables from spills. It also resolves a common problem with individually sealed holes.
Spilled liquids are never limited to one hole; they inevitably drain into several holes over a randomized area. When holes are individually sealed, each must be thoroughly vacuumed, cleaned by pouring fluids into each hole, and then re-vacuumed to remove the cleaning fluids.
It is common that this process is repeated several times to ensure proper cleaning. Any apparatus on the table must be removed to gain access to holes.
SPILLPRUF allows fluids to drain into an aluminum channel, isolating the spilled fluids from the honeycomb material. This system also provides additional damping and structural integrity to the tabletop.
To clean the tabletop, tilt the isolated tabletop (pneumatic leveling valves enable this process), insert a vacuum nozzle in each of the lowest rows of holes, and remove the spilled fluids and cleaning solution. Fluids drain to the lowest hole in each row, removing the need to relocate any apparatus to facilitate cleaning.
KSI Optical Table Damping Options
Quad-Tuned Damping
The Ultimate Performance 5300 Series tables utilize “quad-tuned” damping and broadband damping of the structure and epoxy. This uses individually tuned absorbers embedded in the four table corners and tuned to each optical table's lowest two natural frequencies (bending and torsion).
Known as narrow band selective damping, this is provided by four frequency-tuned, mass-spring resonators dry-damped and tuned to resonant response, 180° out of phase, with the lowest natural mode frequency of the table.
The out-of-phase inertial forces induced in each resonator mass cancels or “absorbs” the motion of the table at its natural frequency.1
“These tuned absorbers provide uniform damping performance over a broad temperature range. Competitive damping using “lossy” materials is temperature sensitive and can vary widely, particularly at lower than normal temperatures.”
Tuned Damping
KSI’s Superior Performance 5200 and 5100T Series tables offer the same construction as the 5300 Series tables, except they utilize tuned absorbers embedded in the table. Additional damping is found in the energy-dissipating properties of KSI’s structural design and the proprietary epoxy used in the table's construction.
Broadband Damping
The 5100H and the 5100 Series are considered economy models, and are damped simply through the energy dissipating properties of the proprietary epoxy formulation as well as the structural design. A thick coating of epoxy that covers 100% of the inside surfaces of the top and bottom skins is responsible for the energy dissipation. This is known as the “free layer” or “broadband” damping and is especially effective at all high-frequency resonances.
Image Credit: Kinetic Systems, Inc.
Better Built Through Better Design to Provide You With Performance Matched to Your Application
KSI’s tables are manufactured with identical precision tooling and high-quality materials. The only difference between models is the amount of internal damping. The modern aerospace epoxy laminated steel-and-honeycomb structural sandwich beam design has been adapted to create highly rigid optical tables and breadboards.
The honeycomb design has high stiffness and structurally efficient lightness, making it ideal for optical tables. The significantly high natural frequency offers less vibration than possible with solid granite or ribbed cast iron designs of the same size.
All of KSI’s standard honeycomb optical tables are equipped with ferromagnetic stainless steel top skins, a high shear modulus, carbon steel bottom skins and sides, corrosion-resisting, hexagon cell honeycomb core, plated steel, and a proprietary damped epoxy formulation. KSI manufactures its own precision honeycomb core. For additional damping and stiffness, steel C-channels treated with a damped laminate are added to form each table's side and end panels.
Epoxy-lamination is completed under pressure with the top surface against a precision master tool plate. When the epoxy cures, the master tool plate's precision flatness is essentially “frozen” and transposed to the honeycomb optical table or breadboard's top skin, or the working surface. Mounting holes on a grid pattern of 1" or 25 mm spacing can be added to the tabletop.
Before assembly, upper surfaces are drilled and tapped utilizing custom-designed CNC drilling machines. Once the chips are removed, the upper surface and SPILLPRUF core are thoroughly cleaned with a high-pressure, high-temperature, neutral detergent spray to assure a chip-free tabletop. Lastly, the steel side and end panels are attached to the top and bottom surfaces through a proprietary method for improved strength.
The upper surface is given a light sand to gain a smooth, non-reflective finish, followed by laminating the sides with a scratch-resistant, high-pressure, granite-like laminate trim. The bottom surface is treated with a scratch-resistant, non-reflective black polyurethane finish. Prior to shipment, each table is checked for dynamic compliance, natural frequency, flatness, and damping.
The tables’ modal frequencies, dynamic compliance, and damping properties are procured using state-of-the-art techniques like impulse force hammers, accelerometers, and a Fast Fourier Transform (FFT) program in a portable computer for storage and graphical presentation.2
A measurement of flatness is taken with an electronic level with a resolution of ± 1 arcsec or 4.8 microinches per inch. These readings are computer-recorded along eight lines representing the perimeter of outside holes, principle diagonals, and centerlines of the table, and subsequently graphed in “Union Jack” format. Standard flatness for all tables is ±0.005 in. (±0.13 mm) in the measured perimeter. Breadboard flatness is ±0.004 in. (±0.1 mm) per 24 in. (610 mm.)
Figure 23.1. Typical 3-dimensional “Union Jack” flatness graph for KSI tables. Image Credit: Kinetic Systems, Inc.
References and Further Reading
- DEN HARTOG, J.P. “Mechanical Vibrations,” Chapter 3, McGraw-Hill Book Co., 1956
- HALVERSEN, W.G. and D.L. Brown, “Impulse Technique for Structural Frequency Response Testing”, Sound and Vibration, November, 1977.
This information has been sourced, reviewed and adapted from materials provided by Kinetic Systems, Inc.
For more information on this source, please visit Kinetic Systems, Inc.