Re: [ATM] Phase Contrast and Foucault image puzzle

["Scott Milligan" <starzkey@charter.net>]

Dale:

Ok, I'll bite: given the age of the patient, my guess is that the strange
features are caused by some combination of surface staining and/or chemical
attack (i.e. partial etching). Do you know how it was stored (humid or dry
room, open to ambient air or enclosed)?  If I'm right, you may be able to
see visual evidence for staining or etching under high intensity white light
with a 5 or 10X magnifier.


Scott Milligan
 
 

-----Original Message-----
From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf Of
Dale Eason
Sent: Sunday, April 15, 2007 1:31 AM
To: atm@atmlist.net
Subject: [ATM] Phase Contrast and Foucault image puzzle

http://home.comcast.net/~doeason/phase_and_foucault.jpg

100k image.

I just learned how to make a phase contrast image of a mirror.  Texerau
calls it the Lyot test in his book. 
The above image has the phase contrast on the left and the Foucault image of
the same mirror on the right.

The fouculat image presents a puzzle to me.  It has a very strange surface.
This mirror was made by a local ATM 60 years ago and it has been in storage
or on a shelf ever since.  I think he was 17 when he made it and made and
used a machine to make it.  It is uncoated Pyrex 10 inch F5.  It has been
cored part way through.  The surface looks very smooth with no hint of what
is seen here except for 2 small scratches and the finger prints close to the
edge.

Has anyone any idea what has caused the groves and winding features seen in
the Foucault image?  None of the features visible on the back show up in
Foucault image.

Dale Eason

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around
http://mail.yahoo.com _______________________________________________
ATM mailing list http://www.atmlist.net/

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