From: Mark Holm 
To: atm{at}shore.net
Reply-To: Mark Holm 


> Actually, the polarizers don't need to be in perfect alignment to do the
> test.  Anything close to the crossed condition will show quite dramatic
> shadows of a tempered piece of glass.
>


I can see the spots in my car windows without any filter when the sun is at
the right angle to provide partial polarization.  The strain in tempered
glass is major and the polarization does not need to be strong to see it.

Mark Holm
mdholm{at}telerama.com

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