[ATM] The S-Mirror, a New Fad?

[stuart452 at earthlink.net (Stuart Hutchins)]

A recent post by Steve Houlihan questioned RTVing a mirror to the support
whiffles in a 9 point cell.  His diagram showed an intuitive S shape
imparted to the mirror.  Many have tried or are thinking about building
cells this way, and there is a lot of debate as to the effects.

My analysis and estimate of the forces and bent profile are at
http://home.earthlink.net/~stuart-atm/id1.html

Warning: this is mathematical and resembles an engineering problem.  Which
it is.

What is calculated is the general shape of the S, not the local distortions
under the pads as we see in the Plop contours. The bending forces for
Steve's cell look to me like 1.5 lbs which will produce visible distortion
in a mirror test or a Plop contour.  For a stout  Pyrex mirror 12.5" by 1.5"
the deviation at the ends of the S looks like something bigger than 1.27
microinches, which is about 1/15 of a green wavelength.  A "best straight
line" (eyeballed, that is) drawn through the S reduces the deflection
something over 1/100 wave.

For the technical types who might be interested in reading the web page,
feedback on or off the list will be appreciated.

Stuart Hutchins