Optical Table Supports, Active Vibration Isolation
Specification Data| Vertical Resonant Frequency* | 1.25 Hz | | Horizontal Resonant Frequency* | 1.0 Hz | | Vertical Transmissibility at 10Hz* | -32.5 dB (97.5%) | | Horizontal Transmissibility at 10Hz* | -30 dB (97%) | | Maximum Load Capacity (set of four) | 5500 lb (2500 kg) |
*See the Specs tab for a Transmissibility Plot and additional specifications. Optical Tables Tutorial TopicsFeatures- Active Vertical and Horizontal Vibration Isolation
- Oil-Free Design
- High-Load Capacity with Excellent Stability
- Compatible with All Thorlabs' Optical Tables
- 3-Way Valves Keep the Optical Table at a Constant Height
- Extremely Low Resonant Frequency
- Fast Settling Time
Thorlabs active vibration isolation optical table supports contain an isolation system that effectively isolates the optical table from vertical and horizontal vibrations throughout the critical 3 to 50 Hz frequency range since most common large-amplitude sources of vibrations found in laboratories vibrate within this range of frequencies (see the Optical Tables Tutorial chapter on Sources of Vibration). The vertical vibrations are isolated from the optical table by a dual-chamber pneumatic isolation system that requires a constant source of compressed air. If the source of compressed air is removed, the optical table will lower until it securely rests on the large-diameter cylindrical optical table supports, albeit the table will no longer be isolated from floor vibrations. The horizontal vibrations are isolated from the optical table by mounting the vertical isolation system on a trifilar suspension system. This proprietary design eliminates the need to use oil-based damping systems that can leak or degrade over time. Each optical table support is also equipped with a 3-way valve. The valve regulates the pressure in the pneumatic isolation system to control the height of the optical table. If the table is displaced vertically, the 3-way valve will allow the pressure in the dual-chamber air reservoir to increase or decrease, as necessary, so that the table is returned to its original height. More information about the function and construction of the optical table supports can be found under the Design tab or in the chapters on Theory of Vibration Isolation and Optical Table Support Design. When the active optical table supports are paired with an UltraPlus or Ultra series optical table and setup in a quite environment even the most vibrationally sensitive photonics experiments like interferometry, holography, and nanopositioning can be preformed. In addition, the active optical table supports can be used to dramatically reduce the vibrations transmitted to an optical table setup in a noisy environment like on the upper floor of a steel framed building (see the Selection Guide tab). To accompany our two optical table thicknesses, 8.3" and 12.2" (210 mm and 310 mm), our optical table supports are available with heights of 23.6" or 27.5" (600 mm and 700 mm) to produce a working height of 35.8" (910 mm). All our optical tables are clearly marked on the underside to show the ideal position of each isolator, and full installation instructions are included. A set of four isolators is capable of supporting loads up to 5500 lb (2500 kg) and is sufficient for use with tables up to 10' (3 m) in length. More than four isolators will be necessary for higher loads, longer tables, or custom-designed joined systems. Please contact tech support to discuss your specific requirements.
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Specification Data| | Active Vibration Isolators |
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| Vertical Resonant Frequency | 1.25 Hz | | Horizontal Resonant Frequency | 1.0 Hz | | Vertical Transmissibility at Resonance | 10 dB | | Horizontal Transmissibility at Resonance | 12 dB | | Vertical Transmissibility at 5Hz | -20 dB (90%) | | Horizontal Transmissibility at 5Hz | -24 dB (94%) | | Vertical Transmissibility at 10Hz | -32.5 dB (97.5%) | | Horizontal Transmissibility at 10Hz | -30 dB (97%) | | Maximum Load Capacity (set of four) | 5500 lb (2500 kg) | | Height Adjustment Range | -0.51", +0.2" (-13 mm, +5 mm) | | Self Leveling Repeatability | ±0.02" (0.5 mm) | | Height | 23.6" and 27.5" (600 and 700 mm) | | Air Pressure (Maximum) | 80 psi (551 kPa) | | Finish | Black Paint |
*The specification data above was measured under a 600 kg load (24% of maximum). TransmissibilityAn optical table system is subjected to continuous vibrational impulses from the laboratory floor. These vibrations may be caused by large machinery within the building or even by wind or traffic-excited building resonances (swaying). Transmissibility is a measure of the isolators efficiency at damping out these vibrations and is defined as the ratio of the amplitude of the transmitted vibration to that of the forcing vibration. Other common ways to represent this ratio are:
Percent of isolation = (1 - transmissibility ratio) x 100 or
Isolation in dB = 20 x log(transmissibility ratio). At resonance, the system amplifies the input vibration so that the transmissibility ratio is greater than one. The transmissibility ratio is dependent on several factors; for instance the ratio will be dependent on the load placed on the isolators. Remember that the isolators only damp vibrations transmitted through the legs of the frame from the floor; air handling systems are often a significant source of vibration that is transmitted to the work surface through the air. As a result, in applications particularly sensitive to vibrations a comprehensive evaluation of the environment is recommended before choosing a vibration isolation platform. For more information on this topic please see our Vibration Isolation Tutorial. Vertical Transmissibility Plot
Common Vibration Sources| Types | Frequency (Hz) | Amplitude (inches) |
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| Air Compressors | 4 – 20 | 10-2 | | Handling Equipment | 5 – 40 | 10-3 | | Pumps | 5 – 25 | 10-3 | | Building Services | 7 – 40 | 10-4 | | Foot Traffic | 0.5 – 6 | 10-5 | | Elevators | Up to 40 | 10-3 to 10-5 | | Building Motion | 46/Height in meters | 10-1 | | Building Pressure Waves | 1 – 5 | 10-5 | | Railroad* | 5 - 20 | +/-0.15g | | Highway Traffic* | 5 - 100 | +/-0.001g |
*Amplitude is reported in dB using the acceleration due to gravity as the reference acceleration. |
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| Feature | Design |
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| Vertical Vibration Isolation | Dual-Chamber Damped Pneumatic Spring: Vertical damping is achieved by the use of a dual-chamber, damped pneumatic spring. The table is supported by the air pressure in these chambers. A piston, clamped to the bottom of the table, is sealed to the upper chamber with a rolling rubber diaphragm, allowing virtually friction-free motion between piston and chamber. Floor or tabletop motion forces air to flow from one chamber to the other through a laminar flow damper. This restriction of airflow damps oscillatory motion between the floor and table, dramatically reducing settling time. The volume ratio of the chambers has been optimized to minimize the resonant frequency of the optical table support while maximizing the damping performance for our complete range of tabletops. | | Horizontal Vibration Isolation | Trifilar Suspension System: Damping of horizontal vibrations is accomplished by supporting the pneumatic vertical isolator on a trifilar suspension system. This innovative pendulum design uses gravity to provide the restoring force after horizontal disturbances. Horizontal oscillations at the system’s resonant frequency are damped by linking the base of the vertical isolator to the outer cylinder with an oil-free vibration-absorbing damper. | | Self-Leveling System | 3-Way Air Valve: To allow for changes in load distribution, the active vibration isolation optical table supports have a self-leveling system based on a precision 3-Way valves that do not compromise vertical isolation when the system is at rest. Because these valves are actuated by tabletop movement, the system returns to its original level position within ±0.5mm (0.02") after disturbances. Additionally, this system allows the table height to be adjusted over a range of 18 mm (0.7".) and can be used to compensate for an uneven floor. These isolators require a constant supply of air. When the air supply is removed, the tabletop rests securely on top of the legs with the isolation system disabled. | | Stable Support | Large-Diameter Cylindrical Design: The large-diameter, free-standing optical table supports provide maximum stability and safety, without the need for cumbersome tie bars that add additional resonances to the support system. The low vertical and horizontal transmissibility of these cylindrical isolators results in the least possible relative tabletop motion while the proprietary design uses no liquids that could leak or degrade over time. | | Height | Cylindrical Steel Supports: To accompany our two tabletop thicknesses, 8.3” and 12.2” (210 and 310 mm), our isolation systems are available at heights of both 23.6” and 27.5” (600 and 700 mm) to produce a working height of 35.8” (910 mm). |
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A vibration isolation system is composed of an optical table and a set of optical table supports where the optical table damps vibrations created on the surface of the optical table and the optical table supports isolate the optical table from floor vibrations while at the same time supporting the optical table. Table 1 below can be used to choose an optical table and optical table supports based on the working environment and application. Alternatively, Table 2 provides a comparison of the performance specifications of the four types of optical table supports sold by Thorlabs. Optical Table and Optical Table Supports Selection Guide| | Quiet Environmenta
(PSD < 10-10 g2/Hz) | Typical Laboratory Environmentb
(PSD ~10-8 to 10-9 g2/Hz) | Noisy Environmentc
(PSD <10-7 g2/Hz) |
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Less Demanding Applications • Pulsed Laser
• General Spectroscopy
• Velocimetry
• Multimode FiberCoupling | Standard,StandardPlus,Performance orPerformancePlus Series of Optical Tables with
Rigid Optical Table Supports | Performanceor PerformancePlus Series of Optical Tables with
Passive Optical Table Supports | Performance, PerformancePlus,Ultra, orUltraPlusSeries of Optical Tables with
Active Optical Table Supports | General Applications in Photonics • Bioimaging
• Raman Spectroscopy
• Micropositioning and Machining | Performanceor PerformancePlus Series of Optical Tables with
Passive Optical Table Supports |
Performance orPerformancePlus Series of Optical Tables
with
Active Optical Table Supports | Ultra orUltraPlusSeries of Optical Tables with
Active Optical Table Supports | Demanding Applications • Nanopositioning
• Submicron Precision
• Phase Related
• Holography
• Single Mode Fiber Alignment | Performance, PerformancePlus,Ultra, orUltraPlusSeries of Optical Tables with
Active Optical Table Supports | Performance, PerformancePlus,Ultra, orUltraPlusSeries of Optical Tables with
Active Optical Table Supports | Ultra orUltraPlusSeries of Optical Tables with
Active Optical Table Supports |
a The lab floor consists of a subterranean slab in a remote environment.
b The lab is in the basement or ground floor of building.
c The lab is on the upper floors of a building or near significant sources of vibrations. Table 1. A selection matrix for optical tables and optical table supports based on the working environment and application. Optical Table Supports Comparison TableTable 2. A comparison table for the optical table supports made by Thorlabs.
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Additional Optical Table Supports
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Supports with Active Self-Leveling Isolators
