From: "Russell Jocoy" 
To: JBHillman{at}ev1.net, atm{at}shore.net
Reply-To: "Russell Jocoy" 


>From: "Jerry B. Hillman" 
>Reply-To: "Jerry B. Hillman" 
>To: 
>Subject: ATM support of thin mirror
>Date: Thu, 14 Aug 2003 17:48:41 -0500
>
>
>Hello everyone,
>Putting my mirror cell on the test stand has relieved the problem
>substantially but after another session which pushed my mirror even closer
>to a parabola, I notice that the problem is beginning to return.  My theory
>is that the closer to a parabola the mirror gets, the more sensitive the
>test is to showing such defects.  To put it simply, the more wave error I
>remove, the easier it is to see the remaining error, and potato chipping of
>the mirror is certainly an error, even though not due to surface defects.
>My copy of plop will not allow me to design a cell with more than 27
>points.
>Is there a version which will allow the design of more than 27 points? Or
>is
>my current support problem due to a manufacturing error on my part? I tried
>to ensure that I put the cell together correctly, but there were terms
>relating to the positioning of the parts that  I did not understand and a
>question to the list failed to produce any helpful replys. Still, I think
>it
>is assembled correctly.
>I discovered a link on Mel Bartels page to a web site describing a counter
>balanced weight system, but it was in French and my high school French
>lessons (30 years ago) did not allow me to read it well enough to be able
>to
>put it to use.
>Any suggestions or help would be greatly appreciated.  I am getting very
>close  to a parabola according to Ronchi and support is becoming a critical
>issue.
>Clear skies, Jerry
>
>
>

("atm{at}shore.net")

   Jerry,      You said that your test rig was elevated 4 feet and the
mirror was on the ground.
It is just my suggestion, but I think your tester should be as high as your
eye standing up.
  What I mean is the tester should be as high as possible, and the mirror as
low as possible.
  A four foot elevation of you scope will happen only when it is absolutely
a still seeing night,
otherwise the veiw will be like looking through water.
             You have a thin mirror, don't break it's back, let it lay back
and see what it has to say then.
   Like I said before it's just a suggestion.  I think that the perfect
readings would come from a
vertical rig.  Bob May or Mel could give you much input on testing of thin
mirrors and how  they
don't like to cooperate.     Russ Jocoy
("atm{at}shore.net")

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