ATM (Test)Plate mirror warnings and mirror flexing

["McHatten, Shawn" <Shawn.McHatten@aliant.ca>]

Mike
	I agree that this should be a valid test. I'd actually like to hear
what would happen to glass if it were to be flexed and then shocked. I've
never tried this but I've read that if you put a magnet on a length of steel
and hit the steel a good whack the steel rod will take on the magnetic
properties by aligning the atomic structure. Would the crystalline structure
of glass work the same way. 
	And does it have to be a mechanical shock. I know that glass is an
insulator but any material will break down if enough electricity is applied.

	And going back to the "is glass a liquid" question; if glass is left
flexed long enough will it finally align to the new structure and thus not
need such a strong flexing cell. (I can just picture every ATMers living
room having 5 or 10 flexed mirrors sitting around for 5 years like fine wine
waiting to ripen.
	Or could it be heated whiling flexing to some point below slumping
temp but enough to allow the internal structure to align under the pressure
but not affect the figure.
	Phew, so many questions. Good thing this isn't a one question per
post kind of list :)
	I don't have the material or ability to be test these theories (at
least not immediately) but would be interested in their outcome. I know I'm
way out of my league here but it is an interesting theory. Thanks for
keeping it on the front burner of our conversations.

Shawn

> -----Original Message-----
> From:	Mike Coslo [SMTP:mjc5@psu.edu]
> Sent:	March 15, 2001 9:27 AM
> To:	'atm@shore.net'
> Subject:	Re: ATM (Test)Plate mirror warnings
> 
> 
> 
> 
> 	Aside from all the strange controversy this thread has brewed, the
> original experiment remains valid. This experiment is testing the
> hypothesis that a plate glass mirror is subtly sensitive to mechanical
> shock, changing figure after being struck. I proposed applying
> mechanical stress to a spherical mirror in the form of striking it with
> a blunt instrument of resilient material, the material chosen to to
> lessen the likelyhood of catastrophic failure. A comparison between pre
> and post shock would be made. This would be only one condition, but if a
> difference was observed, more experiments could be done. Perhaps on
> mirrors that are poorly annealed.
> 
> 	We hear about stress induced figure changes from time to time. Why
> not
> try to find out if there is any truth to them? Otherwise we are just
> repeating things that there isn't really any proof for.
> 
> 	I wouldn't suggest abusing one's telescope mirror this way, only a
> mirror specifically made for this purpose.
> 
> 	- Mike -
> 
> 	
> 
> "Day, Jack" wrote:
> 
> >      Please do not to hit your mirror with anything unless it really
> >      is due to a stuck lap or tool.  And then use extreme caution.  It
> >      is  sad  when bad things sometimes happen to good people.