Talk:Zerodur

CTE values

The data presented for the CTE is all over the place. It is present 3 times and is different each time. Can someone come up with a value and make sure it is all correct??

KAW 73.213.29.16 (talk) 16:59, 30 June 2015 (UTC)

External links modified

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New Lead Section

Hi all, I’d like to propose an edit to address the “lead section may need to be rewritten” issue. This new version is more concise, and focuses on what Zerodur is, its main feature, and where it is used. The rest doesn't seem relevant for the lead section to me. The list of specific telescopes could go in the Applications section (I'll follow up on that later), and the last 3 sentences ("Although it has advantages ...") lack a citation, so I've removed them.

Old lead section

Zerodur is a lithium-aluminosilicate glass-ceramic produced by Schott AG since 1968. It has been used for a number of very large telescope mirrors including GTC, Keck I, Keck II, and SOFIA, as well as some smaller telescopes (such as the GREGOR Solar Telescope). With its low coefficient of thermal expansion (CTE), it is suitable for producing mirrors that maintain acceptable figures in extremely cold environments, such as deep space. Although it has advantages for applications requiring a coefficient of thermal expansion less than that of borosilicate glass, it remains very expensive as compared to borosilicate. The tight tolerance on CTE, ±0.007×10−6 K−1, allows for its use in high-precision applications. References

New lead section
Zerodur is a lithium-aluminosilicate glass-ceramic manufactured by Schott AG. Zerodur has a near zero coefficient of thermal expansion (CTE), and is used for high-precision applications in telescope optics, microlithography machines and inertial navigation systems. References

Thanks for your consideration, and let me know if you have any feedback! Elisabeth at SCHOTT (talk) 12:25, 10 July 2024 (UTC)

 Done Thank you for going through the COI request process! Feel free to tag me when re-adding the specific telescopes, I can't guarantee I'll get to it but I'll try to take a look. Rusalkii (talk) 20:54, 11 July 2024 (UTC)

@Rusalkii, thank you for your quick review! I just wanted to let you know that I've added the expanded Applications section where I've added back in some telescope examples, among others. See below. Regards, Elisabeth at SCHOTT (talk) 13:35, 12 July 2024 (UTC)

Revised Properties Section

Hi all, I’d like to propose some changes to address the “written like an advertisement” issue. I am not entirely sure what the user's issue with the article was, but I presume it is refering to some "better than" comparsions to other materials and products, mentioned in the Properties section. To improve the neutrality of the article, I'm proposing a version that removes those superiority claims. Thanks for taking a look at this proposal, and let me know if you have any input or other thoughts! Elisabeth at SCHOTT (talk) 12:40, 10 July 2024 (UTC)

−

== Properties == Zerodur has both an [[amorphous]] (vitreous) component and a [[crystalline]] component. Its most important properties are: * The material exhibits a particularly low thermal expansion, with a mean value of 0 ± 0.007×10<sup>−6</sup> K<sup>−1</sup> within the temperature range of 0 to 50 °C. This thermal expansion performance is comparatively superior to [[Fused quartz#List of physical properties|that of fused quartz]] by two orders of magnitude. * High 3D [[Homogeneity (physics)|homogeneity]] with few inclusions, bubbles and internal stria (as contrasted to [[Cer-Vit]]). * Hardness similar to that of [[borosilicate glass]], so that it can be ground and polished more easily than [[fused quartz]]. * High affinity for [[Optical coating|coatings]]. * Low [[helium]] permeability. * Non-porous (as contrasted to [[sintered]] ceramics). * Good chemical stability similar to that of [[fused quartz]]. * [[Fracture toughness]] approximately 0.9 MPa·m<sup>1/2</sup>.

+

== Properties == Zerodur has both an [[amorphous]] (vitreous) component and a [[crystalline]] component. Its most important properties are: * The material exhibits a particularly low thermal expansion, with a mean value of 0 ± 0.007×10<sup>−6</sup> K<sup>−1</sup> within the temperature range of 0 to 50 °C. * High 3D [[Homogeneity (physics)|homogeneity]] with few inclusions, bubbles and internal stria. * Hardness similar to that of [[borosilicate glass]]. * High affinity for [[Optical coating|coatings]]. * Low [[helium]] permeability. * Non-porous. * Good chemical stability. * [[Fracture toughness]] approximately 0.9 MPa·m<sup>1/2</sup>.

Elisabeth at SCHOTT (talk) 12:40, 10 July 2024 (UTC)

References

 Done @Elisabeth at SCHOTT, thank you for going through the COI edit process. Rusalkii (talk) 20:42, 11 July 2024 (UTC)

Revised Applications Section

Hi all, I've drafted a new version of the section, in which I've expanded on the application areas including some relevant examples, e.g., the telescopes that I previously removed when I shortened the lead section (see above). Thank you very much for your review! -- Elisabeth at SCHOTT (talk) 13:31, 12 July 2024 (UTC)

Proposed Version for Applications

The Keck II Telescope showing the segmented primary mirror made of Zerodur

The main applications for Zerodur include telescope optics in astronomy and space applications, lithography machines for microchips and displays, and inertial measurements systems for navigation.

In astronomy, it is used for mirror substrates in large telescopes such as the Hobby-Eberly Telescope, the Keck I and Keck II telescopes, the Gran Telescopio Canarias, the Devasthal Optical Telescope, the European Southern Observatory's 8.2 m Very Large Telescope, and the 39 m Extremely Large Telescope.

In space, it has been used for the primary mirror of SOFIA’s telescope, for the imager in Meteosat Earth observation satellites, and for the optical bench in the LISA Pathfinder mission.

In microlithography, Zerodur is used in wafer steppers and scanner machines for precise and reproducible wafer positioning. It is also used as a mirror substrate material in refractive optics for EUV lithography.

In inertial measurement units, Zerodur is used in ring laser gyroscopes.

References

Elisabeth at SCHOTT (talk) 13:31, 12 July 2024 (UTC)

 Done , for future reference you want to use the {{talk ref}} template to consolidate references from one talk page section. I've edited this and the above section to use it. Rusalkii (talk) 22:01, 12 July 2024 (UTC)

Proposed History Section

Hi all, I’d like to propose an additional History section. Thanks for your consideration. Please let me know if you have any feedback! Elisabeth at SCHOTT (talk) 11:19, 6 September 2024 (UTC)

History

Schott began developing glass-ceramics in the 1960s. In 1966, Hans Elsässer, the founding director of the Max Planck Institute for Astronomy, asked the company if it could produce large castings of almost 4 meters using low-expansion glass-ceramic for telescope mirror substrates.

Based on the material development work of Jürgen Petzold, Schott received an order from MPIA for a 3.6 m (12 ft) mirror blank, along with ten smaller mirror substrates in 1969. It produced the mirror blank in December 1973 and delivered it in late 1975.

In 1984, the mirror substrate went into operation in a telescope at the Calar Alto Observatory in Spain. Following this initial order, Schott began to receive Zerodur orders for telescopes around the world.

References

Elisabeth at SCHOTT (talk) 11:19, 6 September 2024 (UTC)

 Question: Could you clarify who MPIA is? ⸺(Random)staplers 18:05, 7 September 2024 (UTC)

Hi @Randomstaplers, the MPIA is the Max Planck Institute for Astronomy, which is linked in the previous sentence. If the reference isn't clear enough, perhaps it could be added in parenthesis after the initial mention? Thanks for taking a look at this! Elisabeth at SCHOTT (talk) 07:52, 9 September 2024 (UTC)

• I'm looking at the source now. I don't get the impression that the order is a particularly notable part of the chapter, so I'm going to leave it out for now. I'm also going going to reword the third paragraph to place less emphasis on the company.⸺(Random)staplers 18:14, 9 September 2024 (UTC)

 Done ⸺(Random)staplers 18:35, 9 September 2024 (UTC)

Hi @Randomstaplers, thanks for implementing the history section.

I think that the first sentence isn't optimal because it sounds like Schott was led by Petzoldt, when he was the person leading the glass-ceramic development, not the company at that point (he only became part of the company's management board in 1988). Additionally, the company began researching glass-ceramics before there was demand for them for telescopes. The company only pursued the development of Zerodur when the initial interest came from the MPIA inquiry via Hans Elsässer (material development is a very time-consuming and expensive process).

I propose changing the first sentence to my initial suggestion: "Schott began developing glass-ceramics in the 1960s." Then I would include the Zerodur development being lead by Jürgen Petzoldt after the MPIA inquiry.

On another note, I don't understand why you changed the last sentence to: "Further orders for mirror blanks subsequently followed." That doesn't tell readers anything about the nature of the subsequent demand... The Lemke source says that following the initial "spark" from MPIA, Schott received many other international orders for mirror substrates for telescopes: "Nach dieser Initialzündung durch die Auftraggeber des MPIA konnte Schott viele Spiegelscheiben in alle Welt verkaufen, die größten mit 8.2 m Durchmesser für die vier Fernrohre des Very Large Telescope (VLT) der Europäischen Südsternwarte ESO." (p. 78).

Let me know if you want me to clarify anything. Elisabeth at SCHOTT (talk) 08:03, 12 September 2024 (UTC)

• @Elisabeth at SCHOTT I'm wondering if you should run it first past Wikipedia DE, since I can't evaluate the second source. Or you might want to ping someone on the Wikiproject to handle this instead.⸺(Random)staplers 02:28, 8 October 2024 (UTC)

  Hi, I am bilingual and gave the texts a thorough read. I went ahead and made some small edits to improve the accuracy. Hope that's ok! Elisabeth at SCHOTT (talk) 12:54, 28 October 2024 (UTC)

See also section

Hi all, I would like to suggest removing links from the See also section:

• Ring laser gyroscope is already linked in the article.
• CorningWare, Macor, and Sitall don't have direct relevance to Zerodur. These are materials with other applications, or seem like randomly selected niche products. Readers can access all of them through the glass-ceramic article, so there is no need to list them here.

Thanks for your consideration! Elisabeth at SCHOTT (talk) 11:36, 15 November 2024 (UTC)

 Not done. Other non-conflicted editors have added those links in good faith which they believe may be of use to other readers. I see no reason for those links to be removed. You seem to have developed the view that Schott have some kind of proprietorial rights over the content of this article and can dictate what they believe does and not belong. I could not disagree more strongly.

If you wish to set up some internet content about Zerodur where other good faith editors cannot contribute then I suggest you use your company's own website for such a non-collaborative venture. Axad12 (talk) 22:05, 15 November 2024 (UTC)

Dear Axad12, I'm not sure why exactly you've declined my request. In your response I can't find an editorial reason to keep these links, and I also don't understand why you believe I am non-collaborative.

The whole point of me getting involved here was to collaborate. My interest in this article started a few months ago because others believed it had multiple issues and asked for help to improve it. Since then I’ve been following the recommended Edit request process and proposed changes here on the talk page, specifically to solicit other people’s input. I'm not sure what exactly is wrong with this approach.

As for my specific suggestions, they're based on my understanding of the Manual of Style, specifically

• As a general rule, the "See also" section should not repeat links that appear in the article's body (as for Ring laser gyroscope)

This seems pretty clear to me. Please help me understand what the reasoning is for not removing this redundant link?

• Links in this section should be relevant (as for the other three links)

This is of course an editorial judgement, and I’m perfectly happy to learn why these links are relevant. For now, I stand by my opinion that at least CorningWare cookware has very little relevance for an article on a glass-ceramic for telescopes / industrial applications. Otherwise we could easily add ten more links to this list.

Anyway, if there's consensus (or at least a good reason) in favor of one or the other, that's fine. But leaving it as is just out of ‘good faith’ towards someone who added it 10 years ago is not a good reasoning to me (otherwise articles would never get improved / updated at all). Regards, Elisabeth at SCHOTT (talk) 17:26, 19 November 2024 (UTC)

My earlier response makes my thoughts on the matter exceptionally clear and I certainly do not intend to argue with a paid marketing operative over whether or not I am right. I am independent, I am familiar with Wikipedia norms, I respect the contributions of non-conflicted users. I am correct. Nor do I intend to be wikilawyered by someone trying to locate some semblance of policy support for their frankly transparently wrong views. Axad12 (talk) 17:34, 19 November 2024 (UTC)