[ATM] If it's in a supremely stiff cell, that does not twist,why would a thin mirror sag?

[artbianconi at blast.net (artbianconi@blast.net)]

Precise match of the C of TE is only a prerequisate for two materials that 
will be attached to each other through some form of bonding. That is not the 
case here. 

The Mirror is Blanchard ground. While some surface marks from that process are 
apparent, I doubt any polishing will be applied. That surface, however will 
perhaps be the molding surface on which the carbon disks are built up. I might 
choose to use a precision die makers marble instead. If I am unsure at this 
point it's because I have not yet run the numbers using the mirror as the mold.

Vaccum bagging will subject the mirror to about 2,500 pounds of atmospheric 
pressure. I've some concern that lack of support caused by the preground 
saggita will allow excessive stresses to build. While it would not likely 
crack the mirror, it could cause it to flex and distort the surface.

In any case, there also is no demonstrated need for the a 1/10 wave precision 
on either surface The mirror will "float" in a thin (0.001 to 0.005") film of 
Teflon that is soft enough to conform to slight surface irregularities and 
slippery enough to float and achieve equilibrium.

I enjoy these exchanges a great deal. I am also appreciative of the feedback 
even though I am not always in agreement with some of the conclusions drawn.

What concerns me is the amount of time I have to spend explaning or justifying 
my design. 

I am part of an engineering support group which meets periodically. Two 
members in the group have a link to a similar bunch of engineers in Corning, 
NY.

Before I commit any more time to the design, I will supply them with the FEA 
results and the models that were used in the analysis. I do not expect any 
serious flaws in the design to be uncovered but I am prepared for anything.

If you don't see me responding as much to these discussions, it's because I 
have other priorities I must address if I expect to eat!

Thanks for the feedback.

Art Bianconi

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