FW: [ATM] Another Astigmatism question, but at the sphere stage

["Jerry" <wa4guu@verizon.net>]

Look at the asymmetry in the two images on the page with the graphs.
Particularly image one shows it best. Do you see the squarness of the right
side of the number one image? The corner is at 3 o'clock. The shadow border
is somewhat square instead of round. The border of the shadow is nearly a
diagonal line on the upper right. It shows in number two also. Look at the
width of the shadow in the upper right compared to the lower right. It is
easy when you know what to look for. There are other signs in there. I only
point out the easiest to see.

Also there is surface roughness which seems to go with astigmatism. Or maybe
astigmatism goes with roughness. I have seen astigmatism on images posted on
the net and usually, in fact every one I've seen with a rough surface. Maybe
it is a result of working too vigorously and maybe too much weight for the
manner of support.

Then if you look at the numerous images a few show it. Also do you see the
hexagon shape of the central depression, just outside the little bump in the
middle? 

Jerry 

-----Original Message-----
From: Guy Brandenburg [mailto:gfbrandenburg@yahoo.com] 
Sent: Sunday, August 28, 2005 7:22 PM
To: Jerry; 'James Lerch'; 'ATM'
Subject: RE: [ATM] Another Astigmatism question, but at the sphere stage

If you can see the astigmatism in those 2 knife-edge
images, you either have much better eyes, or a much
better imagination, than I do. Are you serious, Jerry?
Guy

--- Jerry <wa4guu@verizon.net> wrote:

> Ok! Thanks James. And the astigmatism does show in
> those images.
> Jerry
> 
> 
> -----Original Message-----
> From: atm-bounces@atmlist.net
> [mailto:atm-bounces@atmlist.net] On Behalf Of
> James Lerch
> Sent: Sunday, August 28, 2005 7:02 PM
> To: ATM
> Subject: Re: [ATM] Another Astigmatism question, but
> at the sphere stage
> 
> ----- Original Message ----- 
> From: "Jerry" <wa4guu@verizon.net>
> 
> >Can someone provide Foucault and Ronchi images of
> this astigmatic mirror?
> 
> Jerry,
> 
> I have archived 120+ unmasked Foucault images on
> mirror C, here:
> 
> http://lerch.no-ip.com/atm/MRR/
> 
> Click on Mirror C Results at the top, Section #3,
> sub-section 3 (Between the
> 
> robo Foucault results and the interferometry
> results)
> 
> BTW, each image is flawed by a small speck of dust
> some where in my CCD
> camera. 
> The flaw shows up as a small 'blotch' in the bottom
> center of each image.
> 
> Hopes this helps.
> 
> Take Care,
> James Lerch


Guy  Brandenburg
Washington, DC
My home page:
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html


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