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An optical table is a vibration control platform that is used to support systems used for laser- and optics-related experiments in Optical science, engineering and manufacturing. The surfaces of these tables are designed to be very rigid with minimum deflection so that the alignment of optical elements remains stable over time. Many optical systems require that vibration of optical elements be kept small. As a result, optical tables are typically very heavy and incorporate vibration isolation and damping features in their structure. Many use pneumatic isolators that act as mechanical , reducing the ability of vibrations in the floor to cause vibrations in the tabletop. Optical tables that use pneumatic isolators are sometimes called air tables.
The surface of an optical table is typically stainless steel with a rectangular grid of tapped holes in either metric or imperial units:
Optical breadboards, benches, and rails are simpler structures that perform a similar function to optical tables. These are used in teaching and in research and development, and are also sometimes used to support permanently aligned optical systems in finished devices such as lasers.
Modern optical tables are typically made of top and bottom sheets of steel, aluminum, or carbon fiber, separated by a thick honeycomb lattice structure. The surface usually has a grid of threaded holes which allow the components to be bolted down to fit the optical system layout. Components may also be held to the steel surface by . Often, the table's legs are pneumatic vibration Damping ratio. For even more accurate setups, one also prevents air movements and temperature gradients by enclosing the surface in a box of transparent plastic such as Plexiglas. One may also use a "flowbox", a device which produces a Laminar flow stream of air flowing downwards, kept at constant temperature by special air conditioning.
The metal used to construct modern optical tables has a higher speed of sound than granite and therefore a higher frequency of the first eigenmode. Any vibration produced on the table below this frequency does not produce a resonant response, making the setup less sensitive to vibrations from motorized optics, cooling water pumps, etc. Vibration damping may be added to tables during their construction. As with granite's composite structure, the combination of several stiff materials with different speeds of sound produces a table for which a wide range of vibrations are critically damped. viscosity fluids are used in between the stiff materials, to aid in damping.
The honeycomb structure reduces bending due to the breadboard's own weight, so it can be tilted and forces applied via the soft spring supports accelerate the table as a whole without misalignment. Breadboards can therefore be used in mobile applications, such as on airplanes. Also, one can bolt a breadboard onto an optical table, build up a module of the experiment on it, and then transfer the module as a whole onto another table without the need to realign the components on the breadboard. Similarly, custom-built optical devices are assembled and aligned on breadboards, which are then enclosed in a case and shipped to the customer.
A more sophisticated example is the silicon carbide ceramic toroidal optical bench in the Gaia spacecraft (illustrated), which supports several optical instruments.
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