From: "Jerry B. Hillman" 
To: 
Reply-To: "Jerry B. Hillman" 


Hi everyone,
I was progressing nicely towards a parabola. I got to about 85% parabolized
and then apparently did something wrong during my last session. The stroke
I was using was a w stroke across the full width of the mirror with the
strokes closer together over the center of the mirror. Where before the
ronchi test showed nice curving lines becoming closer and closer to what
Ronchi said they should be, suddenly I have a big "S" turned
sideways right in the center of the mirror. My first thought was that I had
somehow polished astigmatism into the mirror. I turned the mirror 20
degrees and the orientation of the "S" did not change. I turned
it 90 degress and still the orientation did not change. KE test shows a
ying yang pattern that also does not change with mirror rotation. I can not
visualize what is wrong with the surface of the mirror. If it is not
astigmatism, then the surface error eludes me.
 I measured the height of the mirror center from the base to be 9.25 inches.
I measured the height of the light source from the base to be 9.25".
Light source to returning light is .75 inches. The light source is centered
on the optical path and the tester is square with the mirror. I am still
waiting for my web site to be activated or I would post pictures of this.
Since I don't know what it could be other than astigmatism, and if it is
astigmatism, I don't understand why rotating the mirror has no effect, I am
coming to the list for help and advice on what to do. Clear skies, Jerry

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