From: "James Lerch" 
To: "ATM List" 
Reply-To: "James Lerch" 


----- Original Message -----
From: "Bob May" 


>
> That's major astigmatism!

Hi Bob,

Thanks, that was the goal! 

> Did you evern figure out how bad it is quantiatively?

I don't think so, I'm not even sure its possible with a 1 diameter test.

I've given thought to the possibility of adding an option to Robo for
testing across 3 diameters simultaneously (the normal perpendicular
diameter, then +/- 45 degrees) and "Some How" using the +/- 45
degree axis as a 'Point of Reference" after rotating the optic 90
degrees.  I don't know, it might be doable, then again...

In the mean time I did try an alternative method.

I reduced the data from each of the three axis, keeping the same Best Fit
Roc for each test reduction.  Here's the results

Axis A shows overcorrected, 1/2.8 PV wavefront error, & Strehl of 0.75
Axis B shows overcorrected, 1/3 PV wavefront error, & Strehl of 0.79
Axis C shows overcorrected,  1/4.2 PV wavefront error, & Strehl of 0.88

I'm strongly considering coating the optic, putting it in an OTA, and
seeing what I see (Just because I can !)

Take Care,
James Lerch
http://lerch.no-ip.com/atm (My telescope construction,testing, and coating site)

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