[ATM] Impact of stressed glas

[Otterstedt at t-online.de (Heiner Otterstedt)]

Hi Vladimir,

you wrote:

>Yes, it was strange that he rotated the blank in multiples of
>90 degrees  because the stress pattern has similar symmetry.
>45 degrees or 30 degrees would be more appropriate to detect
>pattern rotation details.
>  
>
I think, what Frank wanted to show by rotating the mirror was the excentric
dark region in the middle. He points out in his description, that the X 
pattern
does not rotate with the glass, but this excentric region does.

Ciao, Heiner