From: "CSC" 
To: "Atm" 
Reply-To: "CSC" 


If your knife edge is set to move up & down, then the vertically
arranged shadow edges will jive nicely with the vertically arranged
openings.

Also o.k. with spheres where there are no shadow edges.

Colin

-----Original Message-----
From: owner-atm{at}shore.net [mailto:owner-atm{at}shore.net]On Behalf Of Jerry
B. Hillman
Sent: Monday, June 16, 2003 5:59 PM To: atm{at}shore.net
Subject: ATM Foucault test question for experts



Hi all,
The answer to this may be obvious but I have to ask anyway. Everything I
see and read shows the Couder mask with the openings horizontal. Up until
now I have done it that way and hated how close I have to have my eye to
the KE when testing the outer zones.  Especially since the opening on the
KE side seems to want to disappear behind the KE unless I am VERY close.
Why not put the mask openings vertical?  If the mirror isn't astigmic then
the zone you are testing should be perfectly round, and nulling in a
perfect circle anyway. It shouldn't make any difference where the holes are
as long as they are the same radius out from the center. I tried this and
the openings are much easier to see, but would like some opinions from the
list. Okay, now - If I am wrong, tell me why Clear skies, Jerry

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