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Casting a $20 Million Mirror for the World’s Largest Telescope



 
 
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  #1  
Old September 10th 18, 01:03 AM posted to sci.astro.amateur
RichA[_6_]
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Posts: 995
Default Casting a $20 Million Mirror for the World’s Largest Telescope

On Saturday, 8 September 2018 01:04:15 UTC-4, StarDust wrote:
https://www.youtube.com/watch?v=M2f4zepwcy8

Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope forced engineers to push the design and manufacturing process beyond all previous limits.

Will be fun to see the Moon and it's craters in it! (o:


"Nanometer precision of its curves?" Really? The curves are accurate to one billionth of a meter??
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  #2  
Old September 10th 18, 05:11 AM posted to sci.astro.amateur
Chris L Peterson
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Posts: 9,922
Default Casting a $20 Million Mirror for the Worlds Largest Telescope

On Sun, 9 Sep 2018 17:03:49 -0700 (PDT), RichA
wrote:

On Saturday, 8 September 2018 01:04:15 UTC-4, StarDust wrote:
https://www.youtube.com/watch?v=M2f4zepwcy8

Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope forced engineers to push the design and manufacturing process beyond all previous limits.

Will be fun to see the Moon and it's craters in it! (o:


"Nanometer precision of its curves?" Really? The curves are accurate to one billionth of a meter??


The surface is finished to an accuracy of 20 nm. I don't think it's
unreasonable to characterize that as "nanometer precision".
  #3  
Old September 10th 18, 06:34 AM posted to sci.astro.amateur
StarDust
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Posts: 659
Default Casting a $20 Million Mirror for the World’s Largest Telescope

On Sunday, September 9, 2018 at 5:03:51 PM UTC-7, RichA wrote:
On Saturday, 8 September 2018 01:04:15 UTC-4, StarDust wrote:
https://www.youtube.com/watch?v=M2f4zepwcy8

Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope forced engineers to push the design and manufacturing process beyond all previous limits.

Will be fun to see the Moon and it's craters in it! (o:


"Nanometer precision of its curves?" Really? The curves are accurate to one billionth of a meter??


Like my wifes curves!
Very close!!!! (o:
  #4  
Old September 11th 18, 02:55 AM posted to sci.astro.amateur
RichA[_6_]
external usenet poster
 
Posts: 995
Default Casting a $20 Million Mirror for the World’s Largest Telescope

On Monday, 10 September 2018 00:11:22 UTC-4, Chris L Peterson wrote:
On Sun, 9 Sep 2018 17:03:49 -0700 (PDT), RichA
wrote:

On Saturday, 8 September 2018 01:04:15 UTC-4, StarDust wrote:
https://www.youtube.com/watch?v=M2f4zepwcy8

Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope forced engineers to push the design and manufacturing process beyond all previous limits.

Will be fun to see the Moon and it's craters in it! (o:


"Nanometer precision of its curves?" Really? The curves are accurate to one billionth of a meter??


The surface is finished to an accuracy of 20 nm. I don't think it's
unreasonable to characterize that as "nanometer precision".


Impressive, if true. What wavefront would that equal?
  #5  
Old September 11th 18, 02:57 PM posted to sci.astro.amateur
Chris L Peterson
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Posts: 9,922
Default Casting a $20 Million Mirror for the Worlds Largest Telescope

On Mon, 10 Sep 2018 18:55:32 -0700 (PDT), RichA
wrote:

On Monday, 10 September 2018 00:11:22 UTC-4, Chris L Peterson wrote:
On Sun, 9 Sep 2018 17:03:49 -0700 (PDT), RichA
wrote:

On Saturday, 8 September 2018 01:04:15 UTC-4, StarDust wrote:
https://www.youtube.com/watch?v=M2f4zepwcy8

Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope forced engineers to push the design and manufacturing process beyond all previous limits.

Will be fun to see the Moon and it's craters in it! (o:

"Nanometer precision of its curves?" Really? The curves are accurate to one billionth of a meter??


The surface is finished to an accuracy of 20 nm. I don't think it's
unreasonable to characterize that as "nanometer precision".


Impressive, if true. What wavefront would that equal?


Well, that's on the order of 1/10 the wavelength of the shortest range
the telescope might be used for.

Any decent mirror in an amateur telescope is finished to a few tens of
nanometers. The thing that's impressive here is doing it over such a
huge area, and with mirrors which aren't rotationally symmetric.
  #6  
Old September 12th 18, 01:54 AM posted to sci.astro.amateur
RichA[_6_]
external usenet poster
 
Posts: 995
Default Casting a $20 Million Mirror for the World’s Largest Telescope

On Tuesday, 11 September 2018 09:57:39 UTC-4, Chris L Peterson wrote:
On Mon, 10 Sep 2018 18:55:32 -0700 (PDT), RichA
wrote:

On Monday, 10 September 2018 00:11:22 UTC-4, Chris L Peterson wrote:
On Sun, 9 Sep 2018 17:03:49 -0700 (PDT), RichA
wrote:

On Saturday, 8 September 2018 01:04:15 UTC-4, StarDust wrote:
https://www.youtube.com/watch?v=M2f4zepwcy8

Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope forced engineers to push the design and manufacturing process beyond all previous limits.

Will be fun to see the Moon and it's craters in it! (o:

"Nanometer precision of its curves?" Really? The curves are accurate to one billionth of a meter??

The surface is finished to an accuracy of 20 nm. I don't think it's
unreasonable to characterize that as "nanometer precision".


Impressive, if true. What wavefront would that equal?


Well, that's on the order of 1/10 the wavelength of the shortest range
the telescope might be used for.

Any decent mirror in an amateur telescope is finished to a few tens of
nanometers. The thing that's impressive here is doing it over such a
huge area, and with mirrors which aren't rotationally symmetric.


Depends on how they're doing it. Are they using optical polish for the final stage, or are they using some kind of molecular beam to ablate single layers of glass molecules? Also, laying down the coating so evenly is impressive too.
  #7  
Old September 12th 18, 03:47 AM posted to sci.astro.amateur
Chris L Peterson
external usenet poster
 
Posts: 9,922
Default Casting a $20 Million Mirror for the Worlds Largest Telescope

On Tue, 11 Sep 2018 17:54:04 -0700 (PDT), RichA
wrote:

On Tuesday, 11 September 2018 09:57:39 UTC-4, Chris L Peterson wrote:
On Mon, 10 Sep 2018 18:55:32 -0700 (PDT), RichA
wrote:

On Monday, 10 September 2018 00:11:22 UTC-4, Chris L Peterson wrote:
On Sun, 9 Sep 2018 17:03:49 -0700 (PDT), RichA
wrote:

On Saturday, 8 September 2018 01:04:15 UTC-4, StarDust wrote:
https://www.youtube.com/watch?v=M2f4zepwcy8

Building a mirror for any giant telescope is no simple feat. The sheer size of the glass, the nanometer precision of its curves, its carefully calculated optics, and the adaptive software required to run it make this a task of herculean proportions. But the recent castings of the 15-metric ton, off-axis mirrors for the Giant Magellan Telescope forced engineers to push the design and manufacturing process beyond all previous limits.

Will be fun to see the Moon and it's craters in it! (o:

"Nanometer precision of its curves?" Really? The curves are accurate to one billionth of a meter??

The surface is finished to an accuracy of 20 nm. I don't think it's
unreasonable to characterize that as "nanometer precision".

Impressive, if true. What wavefront would that equal?


Well, that's on the order of 1/10 the wavelength of the shortest range
the telescope might be used for.

Any decent mirror in an amateur telescope is finished to a few tens of
nanometers. The thing that's impressive here is doing it over such a
huge area, and with mirrors which aren't rotationally symmetric.


Depends on how they're doing it. Are they using optical polish for the final stage, or are they using some kind of molecular beam to ablate single layers of glass molecules? Also, laying down the coating so evenly is impressive too.


The video shows what appears to be a sort of typical polishing tool
attached to some kind of NC carriage assembly.
 




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