11 votes
Accepted

Why are telescope mirrors made of glass?

you are partially correct. Glass is used for several reasons. It is a very stable material and will hold its shape well for thousands of years. Glass can also be polished to a high degree of accuracy ...
Natsfan's user avatar
  • 4,484
8 votes

Why are telescope mirrors made of glass?

The accepted answer is correct as far as it goes but to add a bit of why for the claim: jmh> "Glass can also be polished to a high degree of accuracy without having defects" Comes down to glass ...
tomc's user avatar
  • 463
7 votes
Accepted

Why telescope mirror glass shipped as randomly broken chunks of a constant size in cardboard boxes?

The material used for the mirror is indeed E6 Borosilicate manufactured by Ohara corporation as pointed out by @notovny. The fabrication process of a borosilicate glass honeycomb mirror has remained ...
Wilhelmroentgen's user avatar
7 votes

Instead of a 4 meter diameter, 50 liter spinning pool of dangerous mercury, why didn't the ILMT just use an ionic liquid? Or gallium?

Ionic liquids are not reflective. An ionic liquid being poured, from )source( They have different properties, but may are toxic, note the nitrile gloves, the researcher doesn't want to get any of ...
James K's user avatar
  • 119k
6 votes

Instead of a 4 meter diameter, 50 liter spinning pool of dangerous mercury, why didn't the ILMT just use an ionic liquid? Or gallium?

I'll add this to point out that the mercury is managed such that choosing something else might not be worth the bother. The paper by Brajesh Kumar et al. (Monthly Notices of the Royal Astronomical ...
Jon Custer's user avatar
6 votes

How is it ensured that a parabolic shape forms while polishing a telescope mirror?

How is it ensured that a parabolic shape forms while polishing a telescope mirror? While a spherical shape is fairly easy to abtain, a parabolic shape definitely isn't! It's a combination of special ...
Florin Andrei's user avatar
5 votes

Why are telescope mirrors made of glass?

Why are telescope mirrors made of glass? They are not always made of glass. In situations where mass counts and thermal variations can be large, optical telescope mirrors are sometimes made out of ...
uhoh's user avatar
  • 31.3k
4 votes

Need advice on mirror-making for a home-made amateur reflector

Here's what I've learned from making telescope mirrors. Start with a mirror that's of a reasonable size and curvature. It is definitely possible to begin with a 12" f/5 mirror, but the problem is you ...
Florin Andrei's user avatar
4 votes

Need advice on mirror-making for a home-made amateur reflector

I second the comment about Texereau -- originally written in French; it's the best, bar none. You won't need anything else. Remember the old adage that is quicker to make a 4" mirror and then an 8" ...
Mick's user avatar
  • 1,556
2 votes

Why is plasma used to deposit aluminum on the VLT's four large mirrors?

As shown in an ESO image, the mirrors are coated in a giant plasma sputter system, where ions produced in a (presumably argon) plasma are accelerated and strike the pure aluminum, freeing neutral ...
Jon Custer's user avatar
2 votes
Accepted

Why is this telescope so short? How hard is it to make such a fast primary?

I don't have enough room in the comments for this, so I'm writing here, although it's probably not a true answer since I know nothing about that particular telescope. Anyway, if you look at many SCT ...
Florin Andrei's user avatar
1 vote

Why are these telescope mirror makers not upside down? (Daniel K. Inouye Solar Telescope)

I think this seems legit. Why not?
Hagen von Eitzen's user avatar

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