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Re: [ATM] Phase contrast and the 10 incher.

I would guess that for the most part the worm tracks are less than 15 nm.
And I have no doubt they are on surface, the front one.

But what do I know?  I thought it was from a turpentine softened lap, and
the maker put the unfinished undercorrected mirror on the shelf when he went
away to college. School and subsequent life evolution (a stint in the Air
Force, marriage and kids and then a civilian career at Boeing) put that
thing on a back burner for a little while. Well, to make a long story short
(kinda) the lap skidded on the turps. He just put it on the shelf until he
could make a new lap. He intended to come home on spring break and finish
that thing but a semester turned into a decade and then into half a century.
So 60 years later we are looking at fossilized "worm tracks" trying to
figure their history.

Jerry.


-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Arjan te Marvelde
Sent: Wednesday, April 25, 2007 4:33 PM
To: Stephen Koehler
Cc: atm@atmlist.net
Subject: Re: [ATM] Phase contrast and the 10 incher.

Steve,

Based on the clarity of the wormtracks all over the mirror in the foucault
image, I would say they have to be multiple wave faults, if they were
surface features. Such deviations would surely show up in the raw
interferogram, but all I can see is low frequency abberation, and only to
the right edge there's a hint of phase shift.

I'm close to giving up the guessing ... Dale you can reveal the answer now
;-).

   Arjan

----- Original Message ----- 
> So...this experiment is inconclusive.  I think that if the worm tracks
> are on the surface to be picked up by interferometry, it would need
> less noisy interferograms to see them.  I don't think this constitutes
> proof that the worm tracks are below the surface.

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