Optical table
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Laser.jpg/300px-Laser.jpg)
An optical table is a
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 UNCon 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
Materials and construction
Earlier optical table tops were sometimes made of a large slab of highly polished granite or diabase.[3][4] 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.[3][4] Mounting components to a granite surface is also difficult. Granite and diabase are still used for smaller precision-flat surfaces, but optical tables made from these materials are not commonly available today.
Modern optical tables are typically made of top and bottom sheets of
The metal used to construct modern optical tables has a higher speed of sound than
Breadboards
An alternative to an optical table is an optical breadboard. Some optical systems use breadboards made of solid aluminum for later integration with a larger system with some form of vibration control. Most optical breadboards are constructed from steel, aluminum, or carbon fiber sheets with honeycomb structure and can be placed on an ordinary table or workbench. Breadboards are not as good as optical tables, but weigh less and are adequate for smaller optical systems that do not require extremely high levels of mechanical stability. The low weight enables one to support these tables on soft air springs which reduce vibrations coming from the floor, although this increases vibrations due to acoustic noise.
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.
Rails and benches
An optical bench or optical rail is a simpler piece of hardware that provides a linear (or sometimes curved) track along which to mount optical elements. They are often used for simple experiments, especially for classroom demonstrations. Such rails are typically made of steel and designed to be very stiff, with features that allow holders for optical components to be bolted down and easily shifted along the length of the rail. Rails are common in laser assemblies where the beam path travels on a single axis.
A more sophisticated example is the silicon carbide ceramic toroidal optical bench in the Gaia spacecraft (illustrated), which supports several optical instruments.[5][6]
![](http://upload.wikimedia.org/wikipedia/commons/thumb/a/a9/Schema-gaia-cutCleanReduce.png/220px-Schema-gaia-cutCleanReduce.png)
See also
References
- ^ "Approximating Real-World Beam Deflection". www.newport.com. Retrieved 2016-03-15.
- ^ "The need for optical tables". Retrieved January 3, 2014.
- ^ a b Fisher, James. "What you should know about optical tables" (PDF). Newport. p. 2. Retrieved Oct 5, 2017.
- ^ a b Newport Corporation. "Vibration Control". Photonics.com. Retrieved Oct 18, 2012.
- ^ "The Gaia torus is complete". European Space Agency. July 28, 2009. Retrieved Jan 4, 2014.
- ^ "Schematic diagram of the Gaia torus". European Space Agency. July 28, 2009. Retrieved Jan 4, 2014.