Optimized Damping

Broadband Damping
The most important feature of an optical table or breadboard is its resonant frequency. Since resonant frequency and vibration amplitude are inversely related, the resonant frequency should be as high as possible to minimize vibration intensity. Nexus tables and breadboards are broadband damped over a specific range of frequencies. For improved performance, the damping is optimized for each size of table and breadboard offered.

We have performed extensive testing to optimize the thickness/size ratio of our tables. Larger sized tables (at least 10' or 3 m long) are offered with a standard 12.2" (310 mm) or 18.1" (460 mm) thickness for stability. Smaller sizes are available in both 8.3" (210 mm) and 12.2" (310 mm) thicknesses; they can be custom ordered in larger sizes.

Compliance

The most widely used transfer function for the vibrational response of an optical table is compliance. In the case of a constant (static) force, compliance is defined as the ratio of the linear or angular displacement to the magnitude of the applied force. In the case of a dynamically varying force (vibration), compliance is defined as the ratio of the excited vibrational amplitude (angular or linear displacement) to the amplitude of the force causing the vibration. Any deflection of the tabletop is evident by the change in relative position of the components mounted on the table surface. Therefore, by definition, the lower the compliance value is, the closer the optical table is to meeting the primary goal of optical table design: minimized deflection. Compliance is frequency dependent and is measured in units of displacement per unit force (meters per Newton).

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Figure 118A  Compliance Test Schematic

See the Vibration Isolation Tutorial for more information on compliance.

Compliance Measurement Procedure
An impulse hammer is used to apply a measured force to the top surface of the table or breadboard, and transducers attached to the surface detect the resultant vibrations (see Figure 118A). The signals from the transducers are interpreted by the analyzer and used to produce a frequency response spectrum (i.e., a compliance curve). During the development phase of an optical table, compliance curves are recorded at many points on the tabletop; however, the compliance is always greatest at the corners. The compliance curves and data published by Thorlabs are taken with the sensor located approximately 6" (150 mm) from the corner of the tabletop (closer to the edge for small breadboards), with the point of impact just inboard of the sensor. This test location represents the worst case data.

Unique Test Data Certificate
Each individual Nexus product is tested and shipped with a unique test data certificate and compliance curve. This provides more accurate data compared to the industry standard of using a single size-specific compliance curve to represent the entire product line. The compliance curves and data published by Thorlabs are from sensors located on the corner of the table and therefore represent the worst case data.

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Figure 118B  Nexus Table Compliance Testing

Test Results

210 mm Thick Tables
Item #	Table Size (W x L)	Compliance Curve (Click to View)a
T36H / T36HH / T36V	3' x 6'
T38H / T38V	3' x 8'
T46H / T46HH / T46V	4' x 6'
T48H / T48HH / T48HN / T48V	4' x 8'
T58H / T58V	4.8' x 8'
T1020C / T1020CH / T1020P	1 m x 2 m
T1025C / T1025P	1 m x 2.5 m
T1220C / T1220CH / T1220P	1.2 m x 2 m
T1225C / T1225CH / T1225CN / T1225P	1.2 m x 2.5 m
T1525C / T1525P	1.5 m x 2.5 m

310 mm Thick Tables
Item #	Table Size (W x L)	Compliance Curve (Click to View)a
T36J / T36W	3' x 6'
T38J / T38W	3' x 8'
T46J / T46W	4' x 6'
T48J / T48W	4' x 8'
T410J / T410W	4' x 10'
T58J / T58W	4.8' x 8'
T510J / T510W	4.8' x 10'
T514J / T514W	4.8' x 14'
T1020D / T1020Q	1 m x 2 m
T1025D / T1025Q	1 m x 2.5 m
T1220D / T1220Q	1.2 m x 2 m
T1225D / T1225Q	1.2 m x 2.5 m
T1230D / T1230Q	1.2 m x 3 m
T1525D / T1525Q	1.5 m x 2.5 m
T1530D / T1530Q	1.5 m x 3 m
T1540D / T1540Q	1.5 m x 4 m

460 mm Thick Tables
Item #	Table Size (W x L)	Compliance Curve (Click to View)a
T46K / T46X	4' x 6'
T48K / T48X	4' x 8'
T58K / T58X	4.8' x 8'
T510K / T510X	4.8' x 10'
T514K / T514X	4.8' x 14'
T1220E / T1220R	1.2 m x 2 m
T1225E / T1225R	1.2 m x 2.5 m
T1525E / T1525R	1.5 m x 2.5 m
T1530E / T1530R	1.5 m x 3 m
T1540E / T1540R	1.5 m x 4 m

• The compliance curves here are typical, and slight variations may occur between individual tables. Each table is individually tested before shipment and includes a certificate with the individual test data and compliance curve (see Unique Test Data Certificate section, above).

Note: Compliance data will be available soon for models with a greyed out plot icon. Compliance data is measured for each table, and thus will be included with these models upon purchase.

Nexus^® Optical Tables and Breadboard Manufacturing

• Experienced In-House Design Engineers Create Models and Production Drawings
• Dedicated Tables Manufacturing Facilities for Repeatable and Consistent Production
• In-House Vibration Transmissibility and Compliance Testing 
• In-House Welding and Fabrication
• Custom Design Capabilities for Unique Optical Table and Breadboard Solutions
• Lean Manufacturing:
• Cross-Training Allows Staff to Meet Production Demands
• Use of Current Technology Leads to Increased Quality
• Efficient Organization Leads to Time Savings for Customers

Our team has over 25 years of experience designing optical tables, breadboards, and related accessories. We leverage this experience to ensure that our Nexus^® honeycomb optical tables and breadboards always meet two basic design goals: the natural resonances of the table should be as high as possible (well above the frequency of ambient environmental vibrations) and the table should be well damped (to quickly damp vibrations caused by equipment on the surface). To meet these goals, our engineers use a variety of tools to refine their designs, such as finite element analysis (FEA) and SolidWorks. FEA allows our engineers to evaluate various materials and to identify possible unwanted material stresses. SolidWorks is employed to build 3D models of every design.

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Figure 27C  Nexus Table / Breadboard Cross Section, showing the (1) Top Skin, (2) Bottom Skin, (3) Side Panels, (4) Side Rails, and (5) Honeycomb Core

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Figure 27B  Honeycomb Core of a Nexus Table During Manufacturing

Every Nexus optical table and breadboard is designed to be isotropic and symetrical in X, Y, and Z. For optimal thermal stability, only steel components are used in construction; no wood or plastic is used. Each table includes precision machined top and bottom mounting skins, an uninterrupted honeycomb core, and four side panels with finishing trim. See Video 27A for a simplified illustration of how our tables are assembled. For more details on each step in the process, read this tab.

Precision Steel Construction for Thermal Stability

Thorlabs' Nexus tables and breadboards feature all-steel construction, including 5 mm thick top and bottom skins and a 0.26 mm thick precision formed and welded steel honeycomb core. The core is geometrically formed using accurate pressing tools, and geometric pitch is retained by using welded flat shims. The honeycomb core in our Nexus tables and breadboards extends from the top skin to the bottom skin without intermediate layers, leading to a stiffer, more thermally stable product.

The key aspect of the thermally stable Nexus design is symmetrical isotropic steel construction in all axes. Steel components expand and contract similarly, maintaining flatness during changes in temperature. The steel core extends from top to bottom skin without intermediate plastic or aluminum spill management structures that reduce the overall stiffness of the product and introduce a higher coefficient of thermal expansion. Steel side panels are used rather than wood, which can introduce environmental instability due to susceptibility to moisture.

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Figure 27D  Heat-Shrink Packaging Being Applied Over a Nexus Optical Table Prior to Shipment

Machined Finish with Minimized Contamination Packaging

Automated Finishing Process
Our Nexus tables and breadboards feature an automated orbital machined matte finish that is significantly smoother and flatter than our previous product line. The improved surface finish achieves ±0.1 mm (±0.004") flatness over any 600 mm x 600 mm area. Large radius corners are incorporated into the design, resulting in less pointed edges for lab safety.

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Figure 27E  Diagram showing the location of the honeycomb core and side panels, which do not intersect with any screw holes.

Sealed Edges with Anti-Static Packaging
All optical tables ship with a heat-shrink film that protects the table from most contaminants, such as dust, from entering the product during shipment. For additional protection, we offer an optional finishing and packaging service that is suitable for customers that want to minimize the presence of airborne contaminants on the interior and exterior surfaces of the table or breadboard. This includes anti-static packaging, which has a metallic foil inner layer protected by a heat shrink film outer cover, and gap-free edge panel construction to reduce static charge and prevent dust from entering the product.

Mounting Hole Options and Pattern

Individually Tapped, Countersunk Mounting Holes
Prior to bonding the components of the table, each mounting hole in the top surface is tapped and slightly countersunk to ensure that components mounted to the table sit flat. The mounting holes are then cleaned and sealed on the bottom with vinyl film discs (non-sealed models) or sealing cups (sealed hole models, see the Sealed Mounting Holes section). The vinyl film is easily punctured when using a hole for the first time. Cap screws can be finger tightened into the mounting holes of all Nexus tables and breadboards.

Reduced Hole Pattern Border
Our top surface hole patterns extend to the edge of the table or breadboard with only a 12.5 mm (0.5”) border, equal to half of a hole-to-hole spacing. This increases the usable area of the table and improves mounting option flexibility.

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Figure 27F  Nylon Sealing Cups Installation During Manufacturing

Increased Screw Depth and Optional Sealed Holes
Our custom-designed core maker produces precision formed and welded honeycomb core strips. The core is shaped and installed so that it does not intersect with any screw holes (see Figure 27E), allowing screws to be inserted far into the table, all the way to the bottom skin (for non-sealed-hole models). See the Specs tab for specific screw depth specifications, including outer border holes.

Sealed Mounting Holes
Tables and breadboards can be manufactured with nylon sealing cups glued to the underside of the top skin (see Figure 27F) for liquid spill management. Sealed hole tables are available in all sizes and thicknesses, and the maximum screw depth is 1" (25.4 mm).

Mounting Holes on the Bottom Skin
Our breadboards feature at least four mounting holes in the base skin, permitting the secure attachment of standard or vibration isolating feet and allowing more flexibility for integrating breadboards onto tables or into setups in addition to using breadboard stands.

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Figure 27G  Optical tables and breadboards are tapped using a high-speed drilling machine.

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Figure 27H  The surfaces of our tables and breadboards are sanded in our finishing machine.

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Figure 27J  Tables and breadboards are bonded under pressure in our hot press.