[ATM] 7 inch spherical mirror

[Mike Lockwood <melockwo@uiuc.edu>]

Hi,

The "quality" metrics depend on the choice of focus.

Using FigureXP, best focus for transverse error yields TE = 1.25, not 
quite meeting the Millies-Lacroix criteria.  At that focus the 
wavefront error is worse than 1/3 wave.

At another focus (simulated by changing the ROC of the mirror 
slightly), the wavefront error drops to ~1/6.8 waves, while the 
transverse error rises to ~2.5.

So, you can have either a big spot or a small wavefront error, but not 
both unless it is figured to a parabola, representing about one hour 
of gentle figuring work and testing.

Russ, did you start this thread?  (I can't remember and the archives 
don't seem to be up to date.)  Do you have such a mirror?

	Mike Lockwood

Dominic-Luc Webb wrote:
> Interesting points cropping up. Richard, now that you are
> analyzing this, may I ask if you get same amout of coma
> for both sphere and parabola for same aperture stop?


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