[ATM] WG: Focault (sic!) Help

[vladimir sacek]

Berthold Hamburger wrote:

>It is also interesting to observe the Strehl ratio for the isolated
>astigmatism analysis.
>Even the 1/10 wave astig remaining in the mirror currently will reduce
>Strehl ratio to 0.8.

Something is not right with that calculation. There is a constant
relationship between the p-v and RMS error for primary astigmatism,
RMS=(p-v)/(sq.rt.24). With 1/10 wave surface error doubled in the 
wavefront, the RMS is still only 0.041, for 0.93+ Strehl.

Vla