Questions tagged [mirror-making]

Questions about the fabrication of mirrors for reflector telescopes.

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4 votes
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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?

Phys.org's New Indian telescope identifies its first supernova links to the recent arXiv Follow-up strategy of ILMT discovered supernovae. The International Liquid Mirror Telescope is no ordinary ...
uhoh's user avatar
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2 votes
1 answer
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Why is plasma used to deposit aluminum on the VLT's four large mirrors?

In Tim Scott's October 2, 2023 video "The largest telescope that will ever be built*" (note the asterisk, link below) there is a discussion of the "re-silvering" of the four main ...
uhoh's user avatar
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2 votes
0 answers
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Polishing mirror

While polishing the mirror there is a zone in center become more deep. I tried short center over center strokes while keeping the mirror on the top but it does not resolved. What should I do, should I ...
Automation Buddies's user avatar
6 votes
0 answers
122 views

Would it be possible to create a telescope from a hanging reflective cloth?

A chain suspended on two points hanging under gravity forms a curve called a Catenary, which can look pretty similar to a parabola. I'm not sure if this generalizes to the two dimensional case where ...
2080's user avatar
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3 votes
0 answers
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Can you advise on the construction of a large segmented primary mirror (hobbiest)?

I am interested in experimenting with the building of a large parabolic primary mirror constructed from 4" hexagon mirrors mounted on a "rough" parabolic surface with either 3 screw ...
Mike L's user avatar
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9 votes
1 answer
354 views

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

The video MIRROR LAB: Preparing for Casting GMT's Mirror 6 shows the unpacking several hundred boxes full of broken glass from OHARA, packed in styrofoam. The glass chunks are a fairly uniform size of ...
uhoh's user avatar
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5 votes
1 answer
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Why are these telescope mirror makers not upside down? (Daniel K. Inouye Solar Telescope)

The new open access Solar Physics article The Daniel K. Inouye Solar Telescope – Observatory Overview is the first of several papers about the new state-of-the-art solar observatory. For more info see ...
uhoh's user avatar
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4 votes
1 answer
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How to make a 65 cm lens with a 20 cm hole in it for a Hamiltonian telescope?

This answer to What (the heck) is a Hamiltonian telescope? Is this one? confirms that the telescope in the question linked there is indeed as described and that the first lens is a full 65 cm aperture ...
uhoh's user avatar
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13 votes
4 answers
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Why are telescope mirrors made of glass?

Optical telescope mirrors are typically made from endlessly polished glass surfaces that have been aluminised to provide a very smooth surface of reflective aluminium. But why the need for glass at ...
Ingolifs's user avatar
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3 votes
1 answer
451 views

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

The recently discovered object C/2019 Q4 (Borisov) is in the news because it might have an eccentricity greater than one, which means it might be from outside the solar system, though not necessarily. ...
uhoh's user avatar
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8 votes
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How is it ensured that a parabolic shape forms while polishing a telescope mirror?

I understand polishing the mirror with a successively finer abrasive can create a curvature, but how is it possible to obtain a uniform curve that forms a parabola while polishing by hand?
Maverick139's user avatar
4 votes
2 answers
230 views

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

For example, what would be some good references to read first? What sort of glass slab should I use? What size; diameter and thickness. Im a first-time builder trying to build one
Muralita's user avatar