thumb|A laser system on an optical table

thumb|Side view of an optical bench with five riders for various [[optomechanics|optomechanical components]]

thumb|Top view of an optical bench with six riders for various optomechanical components

An optical table is a vibration control platform that is used to support systems used for laser- and optics-related experiments in 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 low-pass filters, 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:

  • metric: M6 on a 25 mm grid
  • imperial: ¼"-20 UNC on a 1" (25.4 mm) grid

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.

Explanation

In optical systems, especially those involving interferometry, the alignment of each component must be extremely accurate—precise down to a fraction of a wavelength—usually a few hundred nanometers. Even small vibrations or strain in the table on which the elements are set up might lead to complete failure of an experiment. Hence, one requires an extremely rigid table which neither moves nor flexes, even under changing loads or vibrations. The surface of the table must also be quite flat, to allow precision optical mounts to make good contact with the table without rocking and facilitate easy assembly of the optical system.

Materials and construction

Earlier optical table tops were sometimes made of a large slab of highly polished granite or diabase. These materials are very dense and stiff, which inhibits flexing and motion of the surface, improving the stability of the optical system. The surfaces can be ground extremely flat, which is beneficial for alignment of optical systems. Such tables were very heavy and expensive, however, and did not do a good job of damping vibrations.

thumb|left|Diagram of [[Gaia (spacecraft)|Gaia space observatory. Item 1 is the toroidal optical bench.]]

See also

  • Optical cage system

References

  • Optical table simulator
  • Fundamentals of Vibration Isolation for Optical Tables