
18.1.
Large Mirrors 449
the normalized autocorrelation function. See Section 11.1 for a discussion of
these degradation factors.
As the errors represented by these factors are independent of one another and
of the figure error, they can be combined in quadrature. Hence
co^
= oj}-j-coi-j-col (18.1.4)
where
co^
is the mean square error (mse) on the wavefi*ont for errors at all spatial
fi-equencies. The overall quality of the mirror is thus given in terms of the separate
errors and the combined error.
We discussed some of the effects of the mid- and high-fi*equency errors on the
point spread function (PSF) in Section 11.1, and extend that discussio ...