RE: [ATM] Calculate Astigmatism

["Robert Turner" <rbturner@charter.net>]

Jim,

Ok maybe I am still a little confused on this calculation. Can you explain
here what the variables are a little more? Is your calculation for the 8"f6
say that the Radius of curvature at 0 and 90 degrees need to be within
.014mm to be passing? Maybe a little elaboration might help understand.

Robert

 Anyway, the required accuracy dR in the radii of
> curvature on two diameters to achieve the accuracy dRMS from primary
> astigmatism is 2*sqrt(6)*(R/r)²*dRMS, with r the mirror
> semi-diameter.  To
> get dRMS to 5 nm (20 nm is a passing mirror) for Texereau's
> standard 8"f/6,
> dR = 2*sqrt(6)*24²*5E-6 = .014 mm.  Oh well, R to the micron instead of
> nanometer - you still can't turn the mirror to that level of accuracy.
>

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