From: "Ray{at}J-Engineering.com" 
To: atm{at}shore.net
Reply-To: "Ray{at}J-Engineering.com" 


Hi All,

When testing a spheroid,  how can you quantify the figure?

As far as I can tell, the edge is good.  I used an oversized lap which
seemed to work rather well.

If I set things up just right, I can get the Ronchi lines (grating /
grating) to bend just a bit.  Hardly noticeable.  It seems to only work at
the few positions where the diffraction images combine or merge just right.
How can I tell how far off the surface is?

In a slitless knife edge test,  at ROC, I can just eek out a few shadows
just before the whole image gets too dark.

I'm working on getting a feel for using these tests and trying to associate
some kind of number to what I see.

(8", f/6.3)

Thanks for any help or web links,

Ray

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