# Talk:Abbe number

WikiProject Glass (Rated Start-class, High-importance)
This article is within the scope of WikiProject Glass, a collaborative effort to improve the coverage of glass on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start  This article has been rated as Start-Class on the quality scale.
High  This article has been rated as High-importance on the importance scale.
WikiProject Physics (Rated Start-class, Low-importance)
This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start  This article has been rated as Start-Class on the project's quality scale.
Low  This article has been rated as Low-importance on the project's importance scale.

## Untitled

On the Cadmium page, http://en.wikipedia.org/wiki/Cadmium, in the "Applications" section, bullet (7) states that there is "no such thing as cadmium blue, green or violet". The Abbe Number article refers to "blue and red cadmium lines". What does this mean?

The article ought to specify whether lower or higher values are better if you want to avoid chromatic aberration. --Jsnow 00:54, 16 June 2007 (UTC)

The article mentions fluor-crown (crown glasses is a group of silicate glasses) but links to fluorite (which is not a crown and not a glass at all but crystalline calcium fluoride, which probably has a high Abbe number and is indeed used for this property). The article on crown glasses mentions fluorite as an additive. Fluorite as a glass additive is otherwise known for making glass turbid (e.g. milk-glass) which would be highly undesirable for an optic glass. The turbidity is likely to depend on amount, other constituents and heat treatment. Some kind of clarification is needed, what is the Abbe number of fluorite and are there indeed fluor-crown glasses?

—Preceding unsigned comment added by 150.227.15.253 (talk) 13:10, 22 March 2010 (UTC)

If the Abbe number describes the properties of a material, then it seems like it is possible to calculate the refractive index at any wavelength based on the Abbe number. Right? And if yes, how?--TeakHoken193.187.211.118 (talk) 11:22, 1 August 2008 (UTC)

Abbe number is best indicated by the greek letter ν (ni). The letter V is acceptable, though, and is indeed commonly used on lens catalogues, but somebody ought to clarify this within the article —Preceding unsigned comment added by 93.144.184.43 (talk) 11:26, 4 March 2009 (UTC)

The appears to be inconsistency in the naming of the green mercury line (546.073 nm). In the upper half of the page it's called the E-line but it's the e-line in the table at the bottom. The table is consistent with [1]. The E-line is a close pair caused by calcium and iron. [2] NoiseJammer (talk) 15:34, 6 August 2013 (UTC)

## Wrong wave lengths in abbe formula?!

There seems to be s.th. wrong with the wave lengths and the corresponding fraunhofer lines, e.g. nC vs. nC'. See the german wikipedia site for more details. Can someone who knows better than me check this and correct it, if neccessary? Thanks. — Preceding unsigned comment added by 192.53.103.242 (talk) 11:28, 27 January 2012 (UTC)

## Inconsistancy

Inconsistancy in two paragraphs , inconsistency between article and Abbe diagram picture provided.

1)"Abbe The number, VD, of a material is defined as

${\displaystyle V_{D}={\frac {n_{D}-1}{n_{F}-n_{C}}},}$

where nD, nF and nC are the refractive indices of the material at the wavelengths of the Fraunhofer D-, F- and C- spectral lines (589.3 nm, 486.1 nm and 656.3 nm respectively). "

and then

2)"An Abbe diagram is produced by plotting the Abbe number Vd of a material versus its refractive index nd. Glasses can then be categorised by their composition and position on the diagram. This can be a letter-number code, as used in the Schott Glass catalogue, or a 6-digit glass code."

If you defined Abbe diagram as using Vd,why bother mentioning VD in the first place ??. Further the Abbe diagram picture showed here clearly stated using nd with is consistant with your 2) but contrary to 1) .

Suggestion, get rid of

)"Abbe The number, VD, of a material is defined as

${\displaystyle V_{D}={\frac {n_{D}-1}{n_{F}-n_{C}}},}$

replace it with the more common

)"Abbe The number, Vd, of a material is defined as
${\displaystyle V_{d}={\frac {n_{D}-1}{n_{F}-n_{C}}},}$

as per Schott Glass work--Gisling (talk) 09:08, 21 October 2013 (UTC).


## Pronunciation

State how you pronounce Abbe.

(Footnotes following aren't mine.) — Preceding unsigned comment added by Jimlue (talkcontribs) 23:06, 1 April 2017 (UTC)