[ATM] Pre-stressed figuring?

[eyesky <eyesky@gmail.com>]

Hi.  First-time poster.

I studied optics briefly in my college physics course, and some
reading on the net got me interested in telescopes, esp. the idea of
making one.  So... I'm just a potential future ATM'er,  just so you
know my background.

In my reading recently, I ran across mention of so-called "stress
figuring," a process whereby the primary mirror is ground as perfectly
as possible to a spherical shape, is aluminized, and then stresses are
applied to it so that, in theory at least, the glass deforms to a
fairly accurate parabolic shape.  Read a bit more at this address:
http://astro.sci.uop.edu/~sas/Newsletter/TTN_StressFiguring.html

Anyway, I was curious if anyone has ever heard of this being done in
reverse?  That is to say, grind a mirror to a spherical shape, deform
the mirror by applying a pushing force (as opposed to the pulling
force described in the above link) to the back of the mirror, and then
again grinding the mirror to a spherical curve.  It seemes to me
that--once the stress was released--the mirror would revert to a new
relaxed shape more similar to the parabola desired.

So...  has anyone ever heard of this being attempted?  If not it would
seem to be an interesting experiment.

eyesky
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