Optical Table Guide

Overview

An optical table is the foundation for building an optical experiment. For over 50 years, Newport's optical tables have contributed to many scientific and industrial success stories across various subjects from fundamental physics to semiconductor manufacturing. Our optical table solutions are designed to fit any performance, budget and delivery need. From very demanding applications like confocal microscopy, spectroscopy or interferometry, to applications under a small budget, Newport has the right optical table for you. When you choose a Newport optical table, you have chosen not only the proven superior performance and quality, but also our wealth of knowledge, experience and committed product support along your way. For application-specific photos, see our optical table galleries on Flickr.


Optical Table wCallouts

This guide will explain these choices to assist you in selecting the optimal optical table for your application.

Separate or Combined System

Optical table tops and supports can be selected and ordered separately as stand-alone items, or they can be ordered as frame based combined systems.

Advantages of choosing separate table tops and supports include more customization – and thus, constructing the optimal system for your application and environment – higher payloads per isolator and maximum storage capacity. Disadvantages of separate table tops and supports include more difficult setup, less mobility and flexibility than combined systems, difficulty in adding casters and potentially higher prices.

VC-rs_series-S

On the other hand, combined optical table systems (INT or OTS) are easier to set up, more mobile, easier to add accessories to (such as casters and shelves) and may be more economical. Newport offers a wide variety of active damped, tuned mass damped and broadband damped tables integrated into a robust frame system with either pneumatic isolation or rigid supports. Disadvantages of combined systems include lower payloads per isolator and possible resonances introduced by the frame structure.

Integrity-rigid

Optical Table Top

An optical table is a stiff platform supporting vibration sensitive equipment. The most critical vibration characteristic of an optical table is its resonances. This is because the table is designed to be as stiff as possible and acts as a rigid body when its resonances are not excited. In other words, when the table is a rigid body there is no dynamic deflection, and the beam alignment on top of the table would not be disturbed. However, a typical optical table has one or sometimes two major resonances and several minor ones. Therefore, damping is needed to reduce the resonance amplitudes and minimize the system deflection when the resonances are excited by ambient vibrations. Three types of damping methodologies are available: Broadband, Tuned Mass, and Active/Hybrid.

Broadband Damping

Broadband damping absorbs and dissipates vibration energies across a broad range of frequencies. It is widely used in anti-vibration tables to reduce the structural vibrations of the tabletop. Typically the broadband damping involves energy absorption materials such as foam, rubber or elastomers. It may also involve mass blocks/plates and rubbers installed along the side of the table to absorb moderate amount of vibrations for a broad frequency range that covers the resonances of a standard size optical table. Broadband damping does not target any specific table resonance or any specific set of frequencies; instead it absorbs and dissipates vibration energies uniformly across the frequency range. It is usually affordable and good for applications that do not require high damping performances. Newport's RPR Reliance™ Series broadband damped optical tables represented the state-of-the-art optical table tops before the advent of tuned damping, and they still offer good value for many less stringent applications.

Tuned Mass Damping (TMD)

A tuned mass damper is a device consists of a mass, a spring, and a damper that is attached to a structure in order to reduce the dynamic response of the structure. It is tuned to a particular structural frequency so that when the table resonance is excited, the damper will resonate out of phase with the structural motion of the structure. Vibration energy is then dissipated by the damper inertia force acting on the structure. TMD is the most effective method among all known passive damping methods, as it concentrates damping efforts where it's needed at the frequencies of dominant resonance modes. It is widely used in various industries for its efficiency and effectiveness of damping, such as the famous Grand Canyon Skywalk, Taipei 101 Building, and NASA's Ares I rocket. Different from broadband damping which absorbs a moderate amount of vibration energy equally over the broad band, TMD targets resonances and as a result is much more effective.

Newport’s patented precision tuned dampers (US patent 8857585) are specially designed with precise tuning capabilities and immunity to load changes up to several hundred pounds. With each damper targeting one major resonance mode of the table, a standard optical table's resonance amplitudes are effectively reduced within a broad range of frequencies. Our RS4000 Series features 6 precision tuned dampers and delivers the best passive damping performance for applications requiring a critical level of damping, such as live cell imaging, high resolution imaging and interferometry. The RS2000 Series features 2 precision tuned dampers to selectively eliminate two fundamental structural table modes and their entire harmonics and is ideal for applications such as biomedical imaging, scanning microscopy, spectroscopy and electrophysiology.

3_DAMPER_TUNABLE

Moreover, because our tuned mass dampers can be tuned to very low frequencies, even Newport's doubled table tops that have low resonance frequencies can be damped –broadband damping, by contrast, could not achieve as good of a result in such a scenario.

For more information about TMD, see our technical note Narrowband Damping with Tuned Vibration Absorbers.
OEM-DoublerTable

Active and Hybrid Damping

ST-Feedback_Schematic-S

Newport introduced the first commercially available actively damped optical tables in 2005. Different from broadband or tuned mass damping that absorbs vibrations passively, Newport’s SmartTable® line of products feature active damping with patented IQ technology (US patent 7320455, 8196891, 8807515, 9086112, 8276873, 8231098, 8651447 and 8857585) that senses vibration in real time and immediately sends out signals to actuators to counteract and cancel the vibrations. It effectively addresses the resonances of optical tables by incorporating two pairs of sensor and actuator in the optical table design and uses an external controller to coordinate the signal processing, enabling the fast and accurate damping response for optical tables. It has a much shorter settling time than passive system and reduces all table resonances within the entire active bandwidth. For more information about active damping, see our technical note Active Vibration Damping.

Hybrid damping combines the advantages of both active damping and tuned mass damping. The active system is able to further reduce vibrations on top of a good foundation created by precision tuned dampers, delivering optical tables and systems with the minimum resonance peaks. Hybrid damping system is the most advanced damping technique for optical tables and provides the best performance optical tables ever in the market. They are ideal for the most demanding applications such as nanostructure studies and fabrication; long exposure holography, spectroscopy and microscopy; ultrafast studies; live cell imaging; and any application that involves constant load changes.

Optical Table Thickness – Does it matter?

The short answer is, yes it does matter. Thickness is considered as structural mass of a structure, and thus contributes to the overall stiffness of the optical table. Thicker optical table provides better stiffness and smaller static deflection under the load. Dynamic deflection would also be reduced, as thicker optical tables require taller honeycomb structures inside without increasing the overall mass significantly. Therefore the stiffness to mass ratio is improved so the rigid body frequency zone of the table is expanded. The most popular thickness choices are 8" (203 mm) and 12" (305 mm). For increased stiffness and minimized deflection, choose 18" (457 mm) and above. For cost effective and less demanding applications choose 6" (152 mm).

Role of table thickness chart

Optical Table Support

If the optical table will be in an environment subject to seismic floor vibrations – for example, from foot and vehicle traffic and building vibrations – then the type of optical table supports should be selected depending on how much vibration isolation is needed by your application. Newport offers pneumatic vibration isolators, passive air mounts and rigid legs to support optical tables.

For the most demanding applications or challenging environments, our S-2000A Stabilizer™ Series pneumatic vibration isolators with automatic re-leveling are the industry's highest performing table supports. For experiments needing lower levels of vibration isolation, SL Series LabLegs™ also provide pneumatic vibration isolation at a very affordable price when automatic re-leveling is not required. And if vibration isolation is not required, RL Series LabLegs™ offer rigid high load support of optical table tops.

S-2000_black-S
These free standing legs provide maximum storage capacity and much higher load capacity. They are not as mobile and flexible compared to a frame system, but they don’t have those possible resonances introduced by frame structures. For more information about vibration isolation, please see our Vibration Isolator Selection Guide.

Combined Table System

Table systems were born due to the increasing demand of easier set up, mobility and accessories capabilities. They usually feature a robust frame system with either rigid support or integrated isolators and could be combined with various accessories such as casters, overhead shelves, hip guards, side shelves, laser safety curtains, etc.

Integrity VCS

Integrity VCS featuring passively damped table top is the best value table system to support basic optical research and development applications, at universities, corporate labs and manufacturing floors. Theses systems deliver comparable damping and isolation performance to other optical platforms at a more affordable price – while also offering accessories to improve platform requirements.

SmartTable OTS

SmartTable OTS featuring actively damped table top was designed specifically for advanced applications in live cell imaging, semiconductor metrology, and precision optical alignment and testing. The integrated accessories and ergonomic designs available with the SmartTable OTS deliver exceptional performance, flexibility and upgradability. The SmartTable OTS is the only optical table system that is field upgradable with three levels of table damping performance and two levels of isolation performance, which could satisfy current requirements but also allow the flexibility needed for future performance improvement.

Understanding the Compliance and Transmissibility Curves

Optical table systems can be characterized by compliance curves for the optical table top and transmissibility curves for the isolation provided by the table supports. Taken together, these two plots show the primary performance capabilities of the optical table system. Knowing how to interpret the two graphs is vital when choosing the most appropriate table system for your application.

The transmissibility curve shows the mechanical filtering properties for the isolator leg—in other words, it gives an indication of how much floor vibration will be transmitted through the leg to the table top. It is a relative measure given as a ratio of vibration at two points: one on the top of the isolator and one on the floor.

TransmisCurve-S

The compliance curve shows the dynamic response of the table top in a free space condition—in other words, it gives an indication of how the surface will change shape in response to vibration. Compliance curves are transfer function curves that show the position response of a point on the table surface to a time variant force applied at the same point. In practice the force is generally applied with a calibrated hammer, which outputs a signal proportional to the force with which it hits the table.

Compliance_Curve-S

For more information, see our technical note Compliance and Transmissibility Curves.

Broadband Damped Optical Tables and Systems

Optical Table Series Technical Description
RPR Series RPR Series Industrial and Educational Optical Tables

Fully sealed holes, 8 - 24 in. thick, up to 5 ft wide by 20 ft long

Applications
  • Manufacturing fiber optics assembly
  • Teaching labs
  • Non-interferometric applications, etc.
Integrity 2 VCS Integrity 2 VCS 4.8 mm Skin Table Systems

Optical table system with frame - same damping performance with RPR Series Industrial and Educational Optical Tables

Applications
  • Basic spectroscopy
  • Multi-mode fiber
  • Micro-positioning, etc.
Integrity 1 VCS Integrity 1 VCS 3.4 mm Skin Table Systems

Optical table system with frame – most affordable optical table system with broadband damping

Applications
  • Manufacturing fiber optics assembly
  • Teaching labs
  • Non-interferometric applications

Precision Tuned Damped Optical Tables & Systems

Optical Table Series Technical Description
RS4000 RS4000 Precision Tuned Damped Top Performance Optical Tables

Highest level of tuned damping with 6 precision tuned dampers.

Applications
High resolution experiments that require highest level of damping
RS2000 RS2000 Precision Tuned Damped Research Optical Tables

Meets competitor’s top performance models, featuring 2 precision tuned dampers.

Applications
Microscopy, spectroscopy and other demanding applications
Upgradable SmartTable Precision Tuned Damped Upgradable SmartTable® Optical Tables

Meets competitor’s top performance models, featuring 2 precision tuned dampers, field upgradeable to hybrid SmartTable performance

Applications
Microscopy, spectroscopy and other demanding applications
Integrity 4 VCS Integrity 4 VCS Table Systems with 2 Precision Tuned Dampers

Optical table system with frame - Meets competitor’s top performance models, featuring 2 precision tuned dampers.

Applications
Microscopy, spectroscopy and other demanding applications
Upgradable SmartTable Upgradable SmartTable® Table Systems with Passive Precision Tuned Dampers

Optical table system with frame - Meets competitor’s top performance models, featuring 2 precision tuned dampers. Casters included and tabletop could be bolted to frame using provided safety clips. Field upgradable to SmartTable active damping using IQ upgrade kits.

Applications
Microscopy, spectroscopy and other demanding applications
Integrity 3 VCS Integrity 3 VCS Table Systems with 1 Precision Tuned Damper

Optical table system with frame - featuring 1 precision tuned damper.

Applications
Microscopy, spectroscopy and other demanding applications

Active and Hybrid Damped Optical Tables and Systems

Optical Table Series Technical Description
Top Performance Hybrid Damped SmartTables Top Performance Hybrid Damped SmartTables®

IQ Active damping plus precision tuned damping, top performance table

Applications
  • Super resolution microscopy
  • Ultra precision nanostructure studies and fabrication
  • Applications that involves constant load changes
  • Super long exposure holography, spectroscopy and microscopy
  • Any application that requires the best vibration control platform
Actively Damped SmartTables Actively Damped SmartTables®

IQ Active damping

Applications
  • Live cell imaging
  • Precision nanostructure studies and fabrication
  • High resolution spectroscopy
  • Applications that involves constant load changes
  • Long exposure holography, spectroscopy and microscopy
  • Ultrafast studies
  • Any application that requires long term stability and sub micron precision
Top Performance SmartTable Systems Top Performance SmartTable® Table Systems with Hybrid Damping

Optical table system with IQ Active damping plus precision tuned damping, top performance table system

Applications
  • Super resolution microscopy
  • Ultra precision nanostructure studies and fabrication
  • Applications that involves constant load changes
  • Super long exposure holography, spectroscopy and microscopy
  • Any application that requires the best vibration control platform
Actively Damped SmartTable Actively Damped SmartTable® Table Systems

Optical table system with IQ Active damping

Applications
  • Live cell imaging
  • Precision nanostructure studies and fabrication
  • High resolution spectroscopy
  • Applications that involves constant load changes
  • Long exposure holography, spectroscopy and microscopy
  • Ultrafast studies
  • Any application that requires long term stability and sub micron precision

Custom Solutions

If our standard optical tables and isolation systems do not quite meet the requirements for your application or environment, please contact us to discuss a custom solution. For over 50 years our extensive design and manufacturing capabilities have delivered customized, damped platforms to numerous academic and industrial customers. Our capabilities include custom shaped granite, honeycomb or Invar structures, non-magnetic honeycomb tables, cleanroom and vacuum compatible structures with either broadband or tuned dampers for optimal stability and vibration reduction. For more information, please see Custom Vibration Isolation Solutions.

Optical Table Selection Frequently Asked Questions

Q: What is the typical thermal bending of optical tables and what type of table should I choose if thermal stability is needed for my application?

A: Under localized heat sources (laser, lamp, etc.), all standard optical tables in the market are very likely to bend a little bit (µrads) because the thermal gradient exists between top and bottom skin, which are thermally isolated by air – no matter whether it is an “all-steel symmetrical isotropic” design. If minimum thermal expansion is absolutely needed, the best way is to isolate your thermal source from tables, or choose Super Invar™ as your table material.

Q: What is the difference between vibration damping and isolation? Why do I need isolators when I already have an optical table top?

A: Vibrations transmitted from the floor to the tabletop is handled by isolators. Those floating legs provide isolation to your experiment and eliminate surrounding floor vibrations like building sway, street traffic or even people walking nearby. Damping, on the other hand, targets tabletop and minimizes its resonances caused by the rest of your experiments or environment. This part is handled mainly by tabletop. Combined together, they kill vibrations and make your optical table the cornerstone of your experiment.

Q: Is optical table the heavier the better? Why not use granite as optical table top?

A: Surprisingly, we don’t want our tables to be too heavy. What matters is the stiffness to mass ratio, and we want this ratio to be as large as possible so that the table has a higher stiffness and expanded rigid body zone. Granite is very flat but it is also very heavy. The mass in granite does not contribute to its structural stiffness; therefore granite is not the ideal candidate for optical table top. Instead, honeycomb structure provides less mass and better stiffness and delivers the best vibration control performance.

Q: Why use composite wood for side panels? Isn’t wood more vulnerable compared to steel in terms of environmental instability?

A: Side panels and edge finish for optical tables do more than just covers. They should contribute to the overall damping performance of the table. The advantage of steel is that it is stiff and provides good environmental stability. The drawbacks are: Like many other hard metals with high elasticity and high density, steel tends to allow vibration or ringing and would resonate with very little natural damping. The wood, on the other hand, is very good at natural damping and eliminate vibrations. This is why ringing bells are always made out of steel/metal and high end hi-fi speakers that require acoustic damping are almost all enclosed by composite wood. But wood is not without any drawbacks – it tends to be more vulnerable than steel under difficult environmental factors. Considering the pros and cons from each side and the fact that optical tables are generally used in house and under controlled environment, Newport decides to use composite wood with moisture protective paint layers which provides superior damping and prevent the side panels from introducing vibrations to the tabletop.

Q: What is the proper way to compare the performances of different optical tables?

A: Optical tables are not complex structures. Modes of rectangular plate-like structures like optical tables had been discussed and depicted in numerous handbooks and textbooks. The most direct way is to compare the compliance curves. Compliance test is the vibration control industry standard to test the vibration damping characteristics of a structure; it is well documented and has been used for decades. The test is done on all corners of the table as those tend to have the highest level of vibration.

Other tests such as non-contact laser scanning vibrometry (LSV) is also sometimes performed. However, LSV test could lead to erroneous conclusions if the test is not staged properly. It requires the laser head to be calibrated and mounted on a tall structure in order to capture the entire table surface. Moreover, it requires a calibrated reference signal for excitation in order to get meaningful data. It is used widely for testing complicated miniature structures, instead of a well-defined large structure such as optical table.