Re: [ATM] Mirror back from coaters with scratches

["tony gondola" <acgna@comcast.net>]

Sometimes scratches can be hard to see on plain glass but really stand out 
once coated. I don't know if this applies in your case but it's important to 
take a very close look at the mirrors surface and note any defects to both 
yourself and the coater. That way there won't be any questions later.....

Tony

----- Original Message ----- 
From: "Hiroyuki HIKITA" <hikita@tkb.att.ne.jp>
To: <atm@atmlist.net>
Sent: Thursday, August 24, 2006 9:39 AM
Subject: [ATM] Mirror back from coaters with scratches


> Hi all!
>
> Lots of wandering through the ATM archives and sheer luck,
> my second attempt to make a 6" F6 mirror came out very well
> with a smooth surface and Waveerror P/V 1/20 Lambda.
>
> Two weeks ago I sent out my second mirror to the coaters.
> Today my 6inch F6 mirror came back from the coaters.
>
> Lesson: NEVER use a cheap coater just to save $50...
>
> The mirror came back with several S shaped scratches about
> 2"x1" in size.
>
> So my question is:
> 1) How obvious are scratches this size under the Foucault test?
>   Could I have missed it under the knife??
>
> 2) Is there a quick way to tell if the scratches went all the way to the 
> glass?
>
> # Hiroyuki HIKITA <hikita@tkb.att.ne.jp>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/ 

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