Re: [ATM] A very rough surface mirror

["Virgil.Johnson" <virgilaj@charter.net>]

Looks like it was stored slightly damp, wrapped in a towel.

I once placed a clean, damp 6" mirror on top of a plastic coffee can lid 
with a paper towel between the mirror surface and the lid.
After a week there was an etched ring on the surface where the lid had a 
raised portion. It took about an hour to polish off.
Your picture has a regular feature that looks like the weave in cloth. But 
you do have more damage than that. Maybe the towel was used to clean an oven 
first.

Virgil Johnson
Raider of the Lost Dark

----- Original Message ----- 
From: "Dale Eason" <atmpob@yahoo.com>
To: <atm@atmlist.net>
Sent: Saturday, October 20, 2007 7:33 PM
Subject: [ATM] A very rough surface mirror


> http://home.comcast.net/~doeason/Surface_images.pdf
> 1meg file.
>
> This mirror has a surface similar to one that Texereau
> shows in his book where he states it was caused by too
> much pressure and too fast a stroke by an over
> enthusiastic mirror maker.
>
> This is about the worst surface I have ever measured.
> I am using the PDF file format because there is a lot
> of detail in these images and one can zoom in and out
> of them easily in that format.  I show real ronchi and
> Foucault images and compare them to the
> interferometric data.
>
> Would anyone care to speculate on the cause of this
> surface?  The mirror is an 8 molded Pyrex blank.  The
> the words "Pyrex made in the USA"  and "8D" molded
> into the back.  The sides are slightly tapered to
> allow it to be removed from the mold. It was once
> aluminum coated but nearly all of it has gone.
>
>
> Dale Eason
>
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