To: atm{at}shore.net
From: Jim Burrows 
Reply-To: Jim Burrows 


At 01:32 2003-06-28 -0400, James Lerch wrote:

>Being the crazy fool I am, I set forth to "Criminally
Destroy" a nice 11" F/7
>optic.  Basically I did everything we are told to avoid while figuring a piece
>of glass.    End result, "Oh yea, I made that puppy astigmatic!"  :)
>
>And here's the same three axes, out side ROC, with an 85lpi Ronchi Grating

At 14:00 2003-06-28 -0700, Bob May wrote:

>That's major astigmatism!  Did you ever figure out how bad it is
>quantiatively?

Following Vladimir's suggestion, I tried various values of A22s (primary
astigmatism, 45ø axis) in Diffract to find a match to James' Ronchi
pictures.  Looked to be about 2000 nm surface PV, 400 nm surface RMS
(5.0E-37 Strehl, not a very good mirror ).   It's interesting that
primary astig mostly just causes the Ronchi image to tilt, so this is
assuming that James had the Ronchi ruling in nice and square.  The hooks on
the ends of the Ronchi shadows are due to higher order stuff - he must have
hit the edge, too.

         -- Jim Burrows
         -- mailto://burrjaw{at}earthlink.net
         -- http://home.earthlink.net/~burrjaw
         -- Seattle N47.4723 W122.3662 (WGS84)

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