RE: [ATM] Touchy Refractive Index

["Thomas" <tomjan@ozemail.com.au>]

Dave, it's still true that you have to do local re-touching and
emperical aspherizing. That said the re-touching issue is much less now
then it used to be due mainly to better glass production methods, but
striea are still going to show up from time to time.

Clear skies,
Thomas Janstrom
http://www.tjanstrom.com
http://www.norsewines.com.au
"Your nobody untill you've been ignored by your seventh cranio-facial
nerve."


-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf
Of Woodchuck
Sent: Monday, 17 May 2004 7:29 AM
To: atml
Subject: Re: [ATM] Touchy Refractive Index


In old books it is said that the variation in refractive index in a
"real" glass of "real" size is always large enough to swamp minor errors
of radius, and that not only is figuring always anticipated, i.e.
emperically aspherizing the final surface, but also secondary retouching
of local areas.  Is this still true? Was it always true?

Dave


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