Re: [ATM] mirror cell design

["Krajci, Thomas J" <KrajciTJ@state.gov>]

>From: "Jerry B. Hillman" <JBHillman@ev1.net>

>Can anyone point me to a version of Plop that supports 54 point cells. 
See: http://www.cs.berkeley.edu/~jonah/18plus/ and download the plop .gr
files.  PLOP designs are available there for up to, ahem, 162 points.  (Or
you can design your own.)
>I am
>currently using a 27 point cell but am having difficulty with astigmatism.
>During one test session I will have perfect, astigmatism free results, then
>the next time I set it up, I will have astigmatism.
This is not a flaw of insufficient support.  If it were...you'd have bad
results every time, consistent to each other.
This is a flaw of stiction in various parts of your mirror cell.  That's why
different re-settings of the mirror/cell give different results...in an
inconsistent fashion.
PLOP does not model stiction, so it won't help you.
See:
http://overton.tamu.edu/aset/krajci/
specifically
http://overton.tamu.edu/aset/krajci/scope-design.htm (very bottom of page)
http://overton.tamu.edu/aset/krajci/cell-bearing.htm
and study up on low stiction parts (ball joint bearings, like Bruce Sayre
uses), or zero stiction parts such as compliant hinges.
I hope this helps.

Tom Krajci
Tashkent, Uzbekistan



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