Re: ATM Wavefront vs: slope error vs: RMS

["Gil Stacy" <gstacy@premierweb.net>]

Greetings, Bob!

Good to hear from you.

(For those who don't know Bob, he's one of the pro's on the list)

Your point is a reiteration of the 2 criteria requirements of Danjon and
Couder for a
good mirror:
1)  Satisfaction of Lord Raleigh's 1/4 wavefront envelope
2)  transverse aberration within M-L tolerance

But there's more.  The two criteria must occur at the same focus.
Dick Suiter discussed this in an article contained in TM 32 wherein he
illustrated this point by showing a 6" mirror (spherical) which met the two
criteria, but not at the same focus.  And of course, the surface must be
smooth and zone free.

Gil