Re: ATM New technical paper on Foucault test accuracy posted

["Bob May" <bobmay@nethere.com>]

Let me add my $.02 in for the grins of it.
The ultimate test of a mirror's capability is the star test.  This is
because this is the one test that actually uses the full mirror to actually
produce an image that we are interested in.
The problem with the star test is that it's not a quantative test, i.e. it
won't say where the errors are or how far off they are. All a star test can
do is say whether the mirror is good or not.
Tests like the Foucault, Wire, Caustic, various Interfrometer tests and to a
lesser degree the Ronchi will show where the problems are but each have
their own limits.  Only the actual usage of the mirror as an image former
will actually test the mirror as a complete optic surface.  Anybody that
says different really doesn't understand what the purpose of the mirror is
for.
Bob May
http://nav.to/bobmay
bobmay@nethere.com