CleanTop Optical Table Performance Series

CleanTop Optical Table performance series
  • Overview and Performance Levels +


    TMC's optical tables and isolation systems offer industry-leading performance and rigidity thanks to an all-steel construction and the highest core density and smallest honeycomb cell area on the market.

    CleanTop Performance series have three levels or damping performance as well as a multitude of configuration options for a variety of use cases. Individual tables can even be mechanically coupled in order to create complex rigid table shapes without loss of damping performance.

    The System 1 optical table support systems (sold separately) have the same configuration flexibility and unparalleled vibration isolation performance.

    Performance Levels
    • Research Grade 784 Series
      Provides the ultimate in optical top performance. Unmatched in the industry, Research Grade performance combines the smallest cell-size and highest core density with the unique CleanTop® design, all-steel construction, and the highest level of structural damping commercially available.
      Research Grade CleanTops are recommended for the most demanding applications including interferometers, holography, and ultra-fast lasers, as well as the most severe floor vibration environments. For the best overall vibration control, consider combining this top with a LaserTable-Base™ support, a hybrid air/piezoelectric, 2-stage vibration cancellation system.
    • Scientific Grade 783 Series
      Scientific Grade has the same design features as Research Grade including core size and density, CleanTop cups, and all-steel construction with reduced damping. Peak compliance levels for Scientific Grade damping exceed peak compliance levels of Research Grade damping by a factor of 4.
    • Laboratory Grade 781 Series
      Provides an economical performance level for the least sensitive applications in less severe floor vibration environments. The Laboratory Grade is appropriate for general lab applications where the primary requirement is for a rigid, flat mounting surface.

    optical table cutaway internal structure
  • The CleanTop Advantage +


    All steel construction. No particle board sidewalls or plastic layer between top skin and honeycomb core. Assures maximum strength and structural integrity

    Smallest core cell size, highest core density. The CleanTop design does not require enlarging the steel honeycomb core cell size because CleanTop cups are cylindrical, not conical as found in plastic layer designs. CleanTop's average cell size of 0.5 in.(2) is at least 50% smaller than that achieved with plastic layer designs assuring the highest stiffness and greatest core-to-skin bonding contact area

    Steel to steel to steel. CleanTop achieves a spill-proof core with only two bonding layers: top skin to core and core to bottom skin. Imitations must add a third bonding layer which weakens the structure: top skin to plastic layer, plastic layer to core, and core to bottom skin.

    Thermal stability. The CleanTop all steel construction assures materials of identical coefficient of thermal expansion ensuring optimal thermal stability. 

    TMC's CleanTop Optical Top is the best method yet for providing a spill-proof, clean, precise, and corrosion resistant optical top with unmatched structural performance. CleanTop is now a standard feature of all TMC optical tops.

    Individual CleanTop cups are epoxy-bonded under each tapped hole after it is tapped and cleaned. Cups are made from chemically resistant nylon 6, and stainless steel (304 alloy) cups are available. Holes are now tapped and countersunk prior to adding the cups to allow the machined top sheet to be thoroughly cleaned with open, rather than blind, holes prior to bonding. The top plate is processed through a custom TMC industrial cleaning center where a high pressure, high temperature cleaning solution is forced through each threaded hole, completely clearing any machining or tapping debris. Several rinse and dry cycles ensure an essentially "sterilized" top surface prior to bonding the cups.

    CleanTop represents another innovation in TMC's long optical top tradition of industry "firsts" including:

    • First spill-proof optical top (CleanTop) 
    • First all-steel optical top 
    • First oil-free optical top 
    • First honeycomb core registered  to the tapped hole array
    • First lightweight breadboard with formed rather than drilled holes
    • First vacuum compatible optical top
    Features:
    • Liquid spills on the surface are contained and cannot reach the top's honeycomb core.
    • The core is completely clean and dry with no residual thread-cutting oils to out-gas.
    • Extremely clean tapped holes make screw insertion smooth and simple.
    • Easy retrieval of small parts dropped into the holes is assured.
    • Since no penetration of the core is possible when dangerous chemicals are used on the top's surface, health hazards will not occur by chemicals reaching the core unnoticed. 
  • 20 Reasons for Choosing TMC CleanTop Optical Tops +


    TMC CleanTop®

     

    Competitive Construction

     


    TMC: Formed Steel Sidewalls

    Other: Particle board sidewalls


    TMC: Steel-to-steel bonding throughout 

     

    Other: Weak plastic layer separates core and top skin


    TMC: High stiffness, small cell size core, individual nylon cups

    Other: Less rigid, large cell size core; molded plastic cups



    1. Sidewalls of TMC tops are 0.075 in. (2 mm) thick, damped, cold-rolled formed steel (see center photo, above), unlike the moisture-absorbing particle board favored by other manufacturers, presumably for its low cost. In addition, steel provides structural integrity unattainable with particle board sidewalls.

    2.TMC’s design does not require enlarging core cell size because CleanTop cups are cylindrical, not conical like molded plastic membrane cavities. Our average cell size of 0.5 in.2 (3 cm2) is at least 50% smaller than molded cavity top designs, assuring the highest stiffness and greatest core-to-skin bonding contact area.

    3. CleanTop achieves a spillproof core with only two bonding layers: top skin to core and core to bottom skin. Imitations must add a third bonding layer, which severely weakens the structure: top skin to plastic layer, plastic layer to core, and core to bottom skin.



    4. Additionally, to avoid excessive epoxy being squeezed into the plastic cups, imitative designs use only the thinnest layer of epoxy between the top skin and plastic layer. The thinness of this layer can produce “voids” when the top is bonded by trapping air, significantly weakening the bond.

    5. TMC employs a proprietary process to clean our machined skins to a level that is virtually “sterilized.” This ensures the cleanest threaded holes and superb epoxy bonding. Furthermore, the cleaning station is in an entranceway to a clean, finishing building so that the cleaned top never sees a heavy, industrial machining environment. In the CleanTop® design, no machining, grinding or sanding of any kind is performed subsequent to this cleaning process.

    6. TMC top skins are stretcher-leveled, stress-relieved, and pressure-bonded against a precision-lapped granite plate, without subsequent grinding—avoiding heat and stress. The finished top is flat within ±0.005 in. (0.13 mm) within the entire tapped hole pattern, regardless of top size, guaranteed.

        
    TMC top skin (above) and competitive design top skin (below) after grinding.

     


    7. Top surfaces of TMC tops are lightly sanded with an orbital pattern to remove burrs and provide a non-glare, non-reflecting finish, without inducing internal stress.


    TMC no-glare surface (above). Ground surface of competitive design creates reflection and glare (below).




    8. Standard mounting holes in TMC tops are tapped, either 1/4–20 on 1 in. centers or M6 on 25 mm centers. Imperial 1/4-20 tapped holes on 1 in. staggered centers and metric M6 on 25mm staggered centers are available at a nominal additional fee. Custom patterns, including large through-holes for cables, etc., are easily accomplished with our multiple 2,000-watt laser machining centers.

    9. All TMC mounting holes are in register with open cells in the honeycomb core (a given with CleanTop® but not necessarily with other designs). This assures that the core is not damaged by subsequent drilling and tapping during manufacture, that the structural integrity of the assembly is maintained, and that all mounting screws can be inserted to full depth without obstruction.

    TMC registered holes (shown without CleanTop® cups.) (top), Competitive non-registered holes (bottom).




    10. Every hole in a TMC top is lead-screw-tapped, the most precise method known, and there are no inserts. Inserts can loosen, and top skins can be distorted when inserts are pressed into undersized holes.

     
    TMC countersunk holes (above) versus non-countersunk holes in competitive design (below)

    11. TMC mounting holes are slightly countersunk to remove ridges and burrs. Every TMC mounting screw can be finger-tightened at first insertion – no wrench is needed. 

    12. TMC’s broadband dry damping approach is the only logical one for an optical top. Others use "tuned" dampers which only work on a discrete frequency. Structural resonances are not discrete and therefore not eliminated but rather "split" into two resonances by tuned dampers.


    13. TMC’s honeycomb core is made of 0.010 in. (0.25 mm) thick steel, work-hardened and plated to prevent corrosion and assure years of service. Steel honeycomb is the ideal material for optical tops since the Young’s modulus of steel is three times that of aluminum.

    14. TMC’s honeycomb core is a closed-cell structure with basic cell size of 0.5 in.2 (3 cm2), giving a core density of 13-14 lbs/ft3 (300 kg/m3), significantly greater than others on the market. The effective core density is 18-20 (16 lbs./ft3) including sidewalls and dampers.

    TMC's honeycomb core. 

     

    18. Structural damping of TMC tops is accomplished using broadband mass dampers which are separate from the core, do not permit hysteresis or creep of the top, and do not detract from the top’s stiffness. 


    19.Our 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.

    20. Our skins, core, sidewalls and dampers are all made of steel and therefore have the same coefficient of thermal expansion. Thus, even in situations with repeated temperature cycling, a TMC top expands and contracts as a whole, assuring structural integrity and preventing long-term internal stress buildup.

  • Specifications +


    • Core: Steel honeycomb, closed cell, 0.01 in. (0.2 mm) thick foil
    • Core shear modulus: 275,000 PSI (19300 kg/cm2)
    • Core cell size: < 0.5 in.2 (3 cm2)
    • Core density: 13.3 lb/ft3 (230 kg/m3)
    • Flatness: +/-0.005 in. (0.13 mm) within entire tapped hole pattern, regardless of table size | +/- 0.004 in. (0.1 mm) over a 2 x 2 ft (60 x 60 cm) area
    • Top skin: 400 series 3/16 in. (5 mm) thick ferromagnetic stainless steel
    • Sidewalls: Damped formed steel channel covered with vinyl
    • Tapped holes: Backed by 1 in. (25 mm) long CleanTop nylon cups. Steel cups optional.

     
  • Performance +


    Damping Performance Comparison Between Grades
    research grade optical table damping performance

    Research Grade: corner compliance data measures the displacement of the table in response to impact by a calibrated hammer. The lack of response below 300 Hz is indicative of extremely high damping and excellent overall structural performance. Compliance was measured on a 48 x 96 x 12 in. table.


    scientific grade optical table damping performance

    Scientific Grade: corner compliance data shows higher peak compliance value than the Research Grade. Compliance was measured on a 48 x 96 x 12 in. table.


    laboratory grade optical table damping performance

    Laboratory Grade: Corner compliance data shows higher amplification at the table's resonant frequency. Compliance was measured on a 48 x 96 x 12 in. table.


    Structural Damping

    TMC has long adhered to the philosophy that dry damping of an optical top 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.

    Our approach to damping of structural resonances has consistently been based on a "broadband damping" approach. "Tuned damping," or using a tuned mass-damper to resonate out-of-phase with a top's bending mode, is a risky approach. First, it assumes the damper can be set to exactly coincide with the resonant frequency of the top. 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. Furthermore, it assumes that only the lowest resonant frequency requires damping when many secondary bending and twisting modes require attention.

    More importantly, the notion of incorporating a tuned mass-damper to suppress a structural resonance is a flawed one. Tuned damping is only effective in damping discrete resonances and is misapplied when used to damp a broadband structural resonance. In simple terms, a tuned damper "splits" a structural resonance into two resonances by creating a coupled mass system.




    TMC's proprietary broadband damping techniques are the most effective way to damp an optical top. This approach works over the entire frequency range of interest, dissipating energy at the top's primary, secondary, and higher resonant frequencies. In addition, performance will not be compromised by adding weight to the top.

    TMC's CleanTops are engineered using the most advanced methods for structural analysis and design. The Operational Deflection Shape shown above was measured using a technique called Laser Scanning Vibrometry (LSV). LSV is among the most sensitive and most accurate non-contact vibration measurement techniques commercially available. It uses the laser doppler effect to measure the behavior of the entire table rather than the behavior one discrete point.

     



    Structural Damping Performance Summary

    TMC optical tops have guaranteed performance levels which are unsurpassed. In addition, with three levels of broadband damping and three environmental choices, TMC offers the most flexibility in choosing a performance level. Guaranteed maximum compliance levels for the maximum damping level are tabulated in the plots below. The standard damping level offers compliance levels a factor of four times higher than those tabulated. The minimum damping level is only recommended for non-sensitive applications. The curves summarize the guaranteed performance levels of TMC optical tops. In addition, table top corner compliance data are presented for the three damping levels available. Data were acquired by impact testing, using a one-pound calibrated hammer, accelerometer, and dual-channel spectrum analyzer. As these examples demonstrate, actual measured performance is often considerably better than our guaranteed performance. 



  • Optical Top Support System Details +


    Choose from Gimbal Piston Isolators or Rigid Supports –
    Micro-g® gives you superior convenience and economy in acquiring precisely the equipment you need for supporting optical tables or other large work surfaces. The unique Micro-g design lets you customize basic features and still have off-the-shelf prices and speedy delivery. There are six categories of options, and the convenient selection charts help you construct a part number for ordering. Systems can also be easily upgraded – whether to convert from a leveling stand to an isolator or add casters – whenever required.

     

    Options
    Isolators/Leveling Posts
    If you need vibration isolation now, the choice is our Gimbal Piston™ isolators, which are unsurpassed in the industry for passive vertical and horizontal vibration attenuation – especially as demonstrated at realistic, low levels of input.

    If a rigid stand will suffice for the present, Micro-g offers an economical leveling mount option with rugged, adjustable jack screws that provide +2 1/2 and - 0 in. (+62 and - 0 mm) of travel. Later, you can upgrade the system to full vibration isolation performance, with a total cost only slightly more than if you had opted for this feature originally.

    Load Capacities Depending on the weight of your table and onboard equipment, you can select support systems with capacities of 1,400, 4,000, 6,000, 10,000, or 15,000 lb (600, 2,000, 3,000, 4,500, or 7,000 kg, respectively). Customized systems can be configured from standard components to support virtually any structure.

    Height Seven post heights are available as standard: 12, 16, 18, 22, 24, 28, and 32 in. (300, 400, 450, 550, 600, 700, and 800 mm, respectively) – though not all sizes are available in all capacities. Taking into account the table thickness and height of equipment components, select the post size that provides the working height you need. Ergonomic convention would dictate 36 in. (900 mm) from floor to table top surface.

    Tiebars For safety reasons, tiebars are recommended. They are mandatory when you choose casters or anticipate upgrading to them. If you require constant access to the area under the table, free-standing support bases will provide more than adequate stability.

    Casters Micro-g's optional casters are of a rugged, heavy-duty design making an installed table easily movable when they are engaged. Once the table is positioned, the casters retract to establish solid floor contact during equipment operation. Like other Micro-g features, they can be integrated at the outset or purchased later if you choose to upgrade. Casters retract externally on the smallest capacity posts, internally on the intermediate, and are not available for the highest capacity. They are not available on posts less than 18 in. tall.

    Configurations A simple four-post frame configuration is the most common; however, depending on the size and shape of the supported structure and on the weight and position of onboard equipment, another multiple support system may be preferred. For unusual size tops or if you have any doubt as to your approach, please call us.



     
  • Accessories and Options +

  • Application Photos +

  • Setup Guides (Video) +

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  • Setup Guides (PDF) +

  • Ordering Information +


    You can now request a quote for CleanTop optical tables via our Online Product Configurator.

    TMC offers a wide variety of standard CleanTop sizes and thicknesses. Custom configurations are available upon request.

       Standard Width
    Standard
    Length
    30 in.
    (750 mm)
    36 in.
    (900 mm)
    40 in.
    (1000 mm)
    48 in.
    (1200 mm)
     
    59 in.
    (1500 mm)
     
    48 in. (1200 mm) - - - -
    60 in. (1500 mm)
    72 in. (1800 mm) -
    80 in. (2000 mm) - - -
    96 in. (2400 mm) -
    120 in. (3000 mm)
    144 in. (3600 mm) - - -
    168 in. (4200 mm) - - -
    192 in. (4800 mm) - - -
    Standard
    Thickness
    8 in. (203 mm) 12 in. (305 mm) 18 in. (457 mm) 24 in. (610 mm)
    Weight Factor 0.225 lb/in.2
    (16 g/cm2)
    0.265 lb/in.2
    (19 g/cm2)
    0.420 lb/in.2
    (30 g/cm2)
    0.475 lb/in.2
    (33 g/cm2)
    Standard Hole Pattern Options 
    Smooth
    (no holes)
    Imperial
    1/4-20 holes
    1" centers 
    Metric
    M6 holes
    25 mm centers
    Imperial Double Density™
    Staggered 1/4-20 holes
    1" centers
     
     Metric Double Density™
    Staggered M6 holes
    25 mm centers
    Support systems are ordered separately. See the Support Systems page.