Re: [ATM] The 15.5 Ultrathin Project, Astigmatism discussion

[GARY FUCHS <gary@rcn.com>]

I can't offer any help, but do hope that you can successfully 
complete this.

Gary Fuchs

---- Original message ----
>Date: Thu, 19 Jan 2006 10:54:54 -0800 (PST)
>From: vorblesnak@peak.org 
>Subject: [ATM] The 15.5 Ultrathin Project, Astigmatism 
discussion  
>To: atm@atmlist.net
>
>I have posted an analysis of what I think is going on here ..
>
>http://www.atmlist.net/contrib/vorblesnak-at-peak-dot-
org/Ronchi%20Pictures/Astigmatism%20Discussion.jpg
>
>I welcome any input on that analysis that anyone wants to add.
>
>I mounted the glass on the wooden base with double stick 
tape at the
>support points suggested by plop.  Using an 8 inch tool I 
polished for
>about a half an hour.  Basic W stroke, tool on top.  I begin to 
see
>improvement and I have hopes for the figure.  I suspect the 
glass is so
>thin that any heat will distort it and mess up the figure.
>
>Two possible directions of work come to mind.  One is to 
continue with the
>sub diameter tool, tool on top.  The other would be to use the 
full
>diameter tool and put the mirror on the top.  OR I could blend 
the two
>approaches.
>
>The sub diameter tool is easier to use and control.  The full 
diameter
>tool, mirror on top, would, by virtue of the stroke etal, return 
the
>surface to a sphere almost guaranteed.
>
>Discussion??
>
>Specs for those new to the topic ..
>15.5 inch diameter
>3/16ths plate glass, slumped to an F6 curve
>true focal length, 73.5 inches
>
>David Davis
>Toledo, OR 97391
>
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