188cm Reflector Restoration - Japan.

[emadmoussa]

 

[Demonperformer]

Interesting video.

I am surprised that this is one every year, although I suppose it depends on how long the total process takes. They also seem to "attack" the surface of the mirror during cleaning a lot more forcefully than I would have expected.

[Gina]

Yes, very interesting.

[Astrobits]

When I was visiting the South African Astronomical Observatory I was told that professional observatories do not overcoat the aluminium on their mirrors because the overcoat interferes with spectroscopy which is a very big part of their work. Therefore the unprotected aluminium deteriorates rather more quickly than it does with  protected surfaces and hence the need to re-coat regularly. I assume that this is usually scheduled for times of minimum interference with with operations i.e. short nights.

Nigel

 

 

[Pompey Monkey]

On 16/07/2018 at 09:06, Astrobits said:

When I was visiting the South African Astronomical Observatory I was told that professional observatories do not overcoat the aluminium on their mirrors because the overcoat interferes with spectroscopy which is a very big part of their work. Therefore the unprotected aluminium deteriorates rather more quickly than it does with  protected surfaces and hence the need to re-coat regularly. I assume that this is usually scheduled for times of minimum interference with with operations i.e. short nights.

Nigel

 

 

The Gran Canaria Telescope engineers regularly re-coat individual sections of the main mirror. The primary comprises 36 hexagonal elements, with 6 spares used for the endless re-coating cycle, so that the scope is not out of action during the process. 

[Astrobits]

11 hours ago, Pompey Monkey said:

The Gran Canaria Telescope engineers regularly re-coat individual sections of the main mirror. The primary comprises 36 hexagonal elements, with 6 spares used for the endless re-coating cycle, so that the scope is not out of action during the process. 

Yes, I expect all the multi-mirror telescopes use that procedure. Certainly that was the plan at the SALT ( South African Large Telescope) when I was there during the construction phase.

Nigel