Re: [ATM] Moulded mirrors

[Mike Lockwood <melockwo@uiuc.edu>]

Hi,

Russell Jocoy wrote:
>       Guy and Jean-Guy and Tony all sent me E-mails 
> concerning moulded blanks and we are obviously way more advanced in this 
> field than I ever could imagine. My basic point was that I can't see a 
> finished telescope mirror surface comming out of a mold if it is made of 
> glass.
>       Now there was a listing of "hydrostone core mirrors" moulded and 
> coated with some type of plastic saying they were 1/4 wave.. I am sorry I 
> don't want a plastic mirror. Maybe this will be the wave of the future but 
> high end optics are mostly made of glass..  Just my opinion  Russ Jocoy

I assume such mirrors can be recoated, but what happens when you put 
them in a vacuum for later recoating?
How are they coated in the first place?
Can they be refigured at all?
What about resistance to UV and other environmental factors?

The Opticast mirrors are indeed Hydrostone-core, and have the same 
cooling rate as Pyrex, or so the manufacturer claims.  But they have 
several times the thermal coefficient of expansion that Pyrex does, so 
temperature affects them more.

Due to its stability and proven durability, I think glass will be the 
choice for precision optics for many years to come.  I sure hope it is 
  - I enjoy working it way too much.

	Mike Lockwood

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