Talk:Optical table

Somebody must have a decent photo of an optical table. Useful for someone who has never seen one.--Srleffler 16:42, 30 December 2005 (UTC)

Is this an optical table? -SCEhardT 05:25, 31 December 2005 (UTC)

Yes, thanks.--Srleffler 05:35, 31 December 2005 (UTC)

Mechanism?

How do the "air springs" work? It allows some damped motion in x and y as well as maintaining pressure to keep the table at a fixed z. How does it work? —Ben FrantzDale 02:49, 2 November 2007 (UTC)

They are literally just pressurized air bladders. Almost all companies enclose the legs in very fancy, pretty setups to disguise how low-tech the technology is; but really you are just dealing with a pressurized air bladder. Everyone basically uses the same stuff, regardless of what is advertised as the quality level. Hewhorulestheworld (talk) —Preceding undated comment added 13:35, 14 October 2011 (UTC).

Hole thread and grid

I'd guess that there are no mixed versions, i.e M6 holes on an inch grid, or 1/4" holes on a 25mm grid, but I don't know this for sure. It is possible to make one but I've never seen one advertised.

I'd also imagine that metric tables are the modern preference, and that imperial ones are more prevalent in the USA.

Perhaps an experienced optical engineer could clarify the situation. —Preceding unsigned comment added by SpareHeadOne (talk • contribs) 13:11, 3 July 2010 (UTC)

I have never seen a mixed version. In the US 1/4-20" on a 1" grid is prevalent. That form is common in Canada as well. --Srleffler (talk) 15:28, 3 July 2010 (UTC)

You do not see mixed grids, no. The standard is a 1" grid of 1/4-20 holes in the USA, and 25 mm grid of M6 holes when dealing with anything outside of the USA. Sometimes you see things like...M6 holes on a 1" grid; but that is uncommon. Hewhorulestheworld (talk)

The spacecraft component illustrated is a kind of "optical table"

Diagram of Gaia space observatory, where (1), a grey torus shape, is a very atypical, structure and material (carborundum), optical bench.

Modern optical tables are typically made of top and bottom sheets of steel, aluminum, or carbon fiber, separated by a thick honeycomb lattice structure. (...) For extreme accuracy and high investment contexts, silicon carbide has been a choice (illustrated).

See the File:Schéma-gaia.png description:

 Diagram of Gaia without its 10-metre diameter sunshade:
 M1, M2 and M3: mirrors of telescope 1
 M'1, M'2 and M'3: mirrors of telescope 2
 Mirrors not shown: M4, M'4, M5, M6
 A: Light path of telescope 1 between mirrors M1—M2—M3
 1: Optical bench (silicon carbide torus)
 2: Cooling radiator
 ...

(references: 1‎, 2, 3, etc.)

So, it is an encyclopedic information for update the article. --Krauss (talk) 02:01, 3 January 2014 (UTC)

This article is focused on optical tables for human use. A frame designed to support optical elements in a spacecraft is a different thing. It has different design constraints, leading to a different choice of materials, structure, and design. I'm not sure we should broaden the article to include this. If we do, it shouldn't be stuck in where it was, as if a silicon carbide torus were just an unusual variation on the typical laboratory optical table. This is a very specialized piece of hardware, and needs to be treated as such.

All Wikipedia-articles about technology shows something about "top" or "the latest"... And frequently need some generalization to accommodate the "latest inovations". Here, I think, there are no "enforced accommodation" (!): 1) the ESA name is "optical bench", and this article is about "optical table and optical bench"; 2) the primary properties of an optical table is not the rectangular shape (can be f.ex. circular!), is the rigidity and the "plane access" (a usual optical bench have only "line access"). --Krauss (talk) 04:31, 3 January 2014 (UTC)

Perhaps the property that diferenciate a "complete table" from a bench is the "isolation from the floor"... But the article say "Modern optical tables are typically made of top and bottom sheets of steel, aluminum (...)", so reader can understand that "the table" is only the main surface, where optical system is plugged. The main isolation (from passing trucks around and building oscilations) is the land lot where floor of the table was builded... And the outer space can be a good lot.
So, about all primary properties of optical tables (and benchs), the Gaia device is not a "very specialized piece of hardware", on the contrary, is more one good example. -- Krauss

I like this material better where it is now, as an example in the section on optical benches. The way it was originally placed in the article did not work as well.

An optical table is a piece of laboratory furniture. It's defining characteristics are that it provides a planar surface on which optics can be aligned in two dimensions, and that it has legs that rest on the floor. If you remove the legs, you have instead an optical breadboard, which can either be placed on a table, or can be installed into some kind of housing. (Many commercial lasers, for example, have an optical breadboard inside the housing.). An optical rail, on the other hand, provides a one-dimensional space for optical alignment. As currently written, the article defines optical bench as a synonym for optical rail. To my mind, the term is a bit more ambiguous than that.

It's not clear to me what the structure of the Gaia bench is, which was why I was hoping to look at some of the information on the ESA site. Does it provide any potential for alignment by translation of optical mounts along the bench? If so, is the translation one-dimensional or two-dimensional? This affects how best to describe it and compare it to other optical benches/rails/breadboards.--Srleffler (talk) 05:33, 3 January 2014 (UTC)

I can't open two of the references you cited. The ESA site seems to be down right now. The link to the Gaia datasheet had something wrong with it. I fixed it. (Some unprintable characters embedded in the text, I think.)--Srleffler (talk) 02:58, 3 January 2014 (UTC)

We can look for another references later, if you deems necessary. -- Krauss

There seems to be a discrepancy in the description of the torus' material. Is it made of carbon fiber, or silicon carbide, or carborundum? These are three different materials.--Srleffler (talk) 03:07, 3 January 2014 (UTC)

Sorry, silicon carbide=carborundum, and carbon fiber is not so rigid as carborundum. As I say above (do you agree?), the main properties of a optical table is the rigidity and the "plane access" to assembly of the optical system. The low thermal expansion coefficient, high hardness, rigidity (near diamond) and thermal conductivity make silicon carbide a desirable material for tables, benchs and other optical devices (including mirrors!)... These material properties allowed, a revolution, a device production for astronomical stereoscopy, that will measure the distance from and between of stars. --Krauss (talk) 04:31, 3 January 2014 (UTC)

My mistake: I confused carborundum with corundum. I'm not sure what you mean by "plane access". I would say that one of the defining characteristics of an optical table is that it has a flat surface on which optical mounts can be translated in two dimensions. If the optics can only be translated in one direction (along a line or curve), then the structure is a rail. If they can't be translated at all, I would be inclined to use bench, particularly if the structure is not linear.--Srleffler (talk) 05:33, 3 January 2014 (UTC)

About "optical mounts can be translated in two dimensions" and "structure is not linear"... I think (as explained below, in a sketch of a taxonomy of optical tables) optical tables for engineering and for "final product" applications, not need all this degrees of freedom. It is because only fine positioning and fine tuning is need (in a optical system that not changes). If you refer the fine tuning of other plane positions and angles, that torus not have, the "precision traveling apparatus" (ex.[1], [2]) is the usual solution. --Krauss (talk) 16:35, 3 January 2014 (UTC)

Some considerations for talk

Sorry my English and no-revision of text, is just for sketching ideas.--Krauss (talk) 16:14, 3 January 2014 (UTC)

Optical table as a product

I was loking for an image of table, and, by google-image search engine, I found a lot of objects with a Brand, like this or this. In now days the optical tables and optical benches are products (!). As we see, there are inherent properties,

• rigid planar surface;
• mechanical isolation;
• ...
• standard shapes and sizes, and standard holes "M6 on a 25 mm grid" (like a LEGO plataform)

And, as a product, the table manufacturer offers diferents variations and relatins of quality/price for users... The needs of users bring the requirements of optical tables and benches as products... There are some main groups of users and uses,

kind of user	general needs	need of optical system changes
Scientific researcher:	do "so generic" and high precision experiments in their research laboratories.	HIGH (all month ou year and many elements change).
Scientific teaching:	the researcher can be a professor, that usually do old (lo precision) experiments with their students in a teaching laboratory.	HIGH (all week or month, less complexity and less element-changes)
Engineering researcher:	do "specialized" experiments in their research laboratories.	medium or low
Optical system user of a (handmade or) low scale industry poduct:	the optical system is a final product, not changes, but need some "standard platform" (standard table or bench), because is cheaper than build a new/specific one.	no change
(idem) of a mass production:	optical systems produced in a assembly line ... No need for "standard platform", because the "specific/simpler platform" is cheeper than an standard one in the mass production.	no change

Summary: we can use something like the introdutory explanation, "an optical table is (...) used (...) for optics experiments and engineering". We can use this two "classes of use and users" as taxonomic groups:

• tables and benches for optics experiments: the uses ranging from high precision scientific research to scientific teaching and student work. The optical system changes with high frequency (from weeks to semesters).
• tables and benches for optics engineering: the uses ranging from engineering research to low scale industry production. Some optical systems (of research) changes with low frequency (from months to years); some (of final products) never changes.

I think that in the current state the article have some bias to "(scholar) optics experiments" view, and not show aspects of "engineering needs".
This will be a "front door" for new encyclopedic information (expand article) about table and bench of engineering and industrial applications.--Krauss (talk) 16:14, 3 January 2014 (UTC)

You are probably right that engineering and manufacturing use of optical tables, breadboards, and rails is underrepresented in the article. I don't think the table above would be a good addition, but some discussion of the various uses would be useful.--Srleffler (talk) 03:23, 5 January 2014 (UTC)

Rewriting explanation paragraph

English is not my language, but reading I see that (for non-technical/scholar people), is dificult to understand, and there are some encyclopedic information that we can add. Only little changes:

1. "Even small vibrations or strain in the table" can be changed to "(...) or thermal strain in (...)". It is for introduce the need of thermal stability of table material.
2. About scale and origins of the mechanical vibration: non-technical/scholar people not know the problem... For didactic purposes, the problem can be introduced with comparisons and contextualizations... This is more difficult, and my text (below) is only a clue.

So, NEW TEXT:

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 thermal 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.

The vibration of the optical system does not just come from the movement of people around it. As is knowed about old wine cellars, the choice of building and land lot is also an option to reduce vibration. A basement vibrates less than the tenth floor of a building, and land lot near near train tracks vibrates more than an isolated lot. Because not every laboratory can be built in an ideal land lot and ideal building, the optical tables are also able to isolate optical system from environment's mechanical perturbations.--Krauss (talk) 16:14, 3 January 2014 (UTC)

Thermal strain is not the only kind of strain that is relevant, and is probably not the most important. The key is the mention of "changing loads" in the next sentence. Strain due to load changes is a big deal: a key property of a good optical table is to prevent misalignment of the optical system due to flexing of the table when other components are moved around on the table's surface. If you try to build an interferometer or a laser on a simple aluminum plate rather than an optical table, you find that your system's alignment is affected by moving things around on the surface.

An extended explanation of vibration is a good idea.--Srleffler (talk) 03:32, 5 January 2014 (UTC)

2014 SUGGESTIONS

Some suggestions for enhancement of the article,

1. Add an image with "only the table" or "only the benches". Examples [3], [4]... We can use a galery at the end of article. As you say in 30 December 2005, is "useful for someone who has never seen one". Perhaps, also, a diagrammatic illustration indicating table parts, like the rigid surface and the dampers.
2. Add an classification of main kinds of use, to organize different kinds of products and properties. This will be a "front door" for new encyclopedic information about table and bench of engineer and industrial applications, that not occurs into experimental (scholar) laboratories.
3. Change the first paragraph of "Explanation" section.
4. Add some words about use of (already discussed) silicon carbide as the "best today" alternative (in high cost projects) material for optical table surfaces and optical benches.

--Krauss (talk) 16:14, 3 January 2014 (UTC)

Adding a picture or pictures is good if you can find any that are public domain or licensed for use on Wikipedia. Due to copyright restrictions we generally can not take photos that we find on the web. These are nearly always copyrighted.

I don't see the value in adding a big table classifying various uses of optical tables, as you introduced above. We can and should say more about engineering and industrial use, but without focusing so much on classification.

Adding more discussion of vibration sources to the explanation section is a good idea. Thermal strain should be discussed too, but without replacing the reference to mechanical strain due to load on the table, which is much more important.

I would like to see references supporting whatever we say about use of silicon carbide for optical benches. I see the ESA site is up now. I'll take a look.--Srleffler (talk) 03:48, 5 January 2014 (UTC)

I added the fact that the torus is silicon carbide ceramic. The existing references do not support the claim that this material is the "best" for optical table surfaces or benches, in general. This spacecraft element is a highly specialized structure, with distinctive requirements. --Srleffler (talk) 04:21, 5 January 2014 (UTC)

Could someone with expertise, add an article about "air table", that physics lab device

Could someone with expertise, add an article on "air table"? Air tables are those devices used in physics labs to demonstrate motion without friction. An air table is described at this page https://www.eiscolabs.com/products/airtbl Right now, a search for "Air table" redirects to the article on "Optical table", a completely different device.

136.53.61.128 (talk) 09:39, 13 October 2019 (UTC)