Re: [ATM] A very rough surface mirror

["Francis J. O'Reilly" <foreilly@verizon.net>]

Dale,

I would think that it was the result of a very hard lap, too fast stroke and 
very poor pitch lap to mirror contact. That being said, with a new lap of 
good quality, use 1 tablespoon of aluminum hydroxide oxide to one quart of 
water for about an hour then rinse throughly, (Note, this I politely 
disagree with Guy on this matter) to clean the rest of the aluminum coating 
followed by half an hour of tool on top followed by half an hour of mirror 
on top, and the mirror should be pretty close to returning to a sphere.

As to Guy's asertion that a caustic bath is injurious to a mirror's figure, 
My experience is counter to his assertion. I would however prefer to 
continue this debate using conclusions drawn from the sciences, rather than 
our bare assertions that it does or does not affect the figure. Can anyone 
offer if  not chemical equations, at least an explanation as to why this may 
or may not be?

Thank you all.

Francis J. O'Reilly
----- Original Message ----- 
From: "Dale Eason" <atmpob@yahoo.com>
To: <atm@atmlist.net>
Sent: Saturday, October 20, 2007 10:33 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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