RE: ATM ? Test for Strain in Coated Mirror

["omegatroid" <omegatroid@hotmail.com>]

You must not shine polarized light on a coated mirror.  The government has special police to take you away if you try anything that simple that is not sanctioned in official books like MIL-HDBK-141.


-----Original Message-----
From:	"owner-atm@shore.net" <owner-atm@shore.net> on behalf of	"Jan and Rod Shea" <jnrshea@comcast.net>
Sent:	Saturday, October 25, 2003 2:53 AM
To:	"atm@shore.net" <atm@shore.net>
Subject:	ATM ? Test for Strain in Coated Mirror


Hello All,

Does anyone out there know a way to test for strain or annealing problems in
a coated mirror?  Can you shine polarized light at the back of the mirror
and look at the reflection off the back of the coating through a polarizing
filter?  Would this double pass through the glass change what I would see?
I am also having a little bit of trouble rigging a 1.25" polarizer onto a
flashlight and getting a beam wide, bright, and even enough for this 24"
mirror.  Seems like I could get a large polarized screen, or try a
reflection from a large, flat, second surface mirror once the sun comes out,
but has anyone else come up with a simpler way?

Thanks,

Rod