Re: Foucault test limitations was [ATM] (no subject)

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

Pretty much, the results will be in that range.  I'll note that 1/10th wave
is essentially perfect and more than enough for any telescope mirror in the
atmosphere.  Peter Ceravolo sort of proved that a mirror of 1/8th wave on
the surface (1/4 on the wavefront) was good enough for most works while a
1/16th surface was only occasionally detectable as being a better mirror.
----- Original Message -----
From: Geoff Nelson <gjnelson@absamail.co.za>
To: atml <atm@atmlist.net>
Sent: Friday, May 14, 2004 12:47 AM
Subject: Re: Foucault test limitations was [ATM] (no subject)


> I meant the inability of the tester to gauge the zone. If we remove
> can remove the human interpretation would the accuracy be in the
> region always of 1/40th wave or 1/100th wave. If I moved to the image
> based reduction of the test would I get rid of my lack of skills and
> so be in a better position to judge what is happening to the mirror.
>
> From:           "Bob May" <bobmay@nethere.com>
> Subject:        Re: Foucault test limitations was  [ATM] (no subject)
> Date sent:      Thu, 13 May 2004 08:59:06 -0700
> To:             "atml" <atm@atmlist.net>
>
> > What do you mean by errors?
> > The biggest error in the Foucault test is the inability of the average
> > tester to be able to match the shadows correctly and get the right COC
> > for the zone. All the rest of the error sources, the ones that are
> > sort of inherent in the test, are all down in the 1/100th wave and so
> > forth, an area where it is difficult to even consider for anybody as
> > the test usually tops out in the 1/40th of a wave because of the
> > readings granularity. Bob May http://nav.to/bobmay bobmay@nethere.com
> > NEW! http://bobmay.astronomy.net
> >
> >
> >
> >
>
>
> _______________________________________________
> ATM mailing list http://www.atmlist.net/

_______________________________________________
ATM mailing list http://www.atmlist.net/