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Fused Mirrors

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Posted by Steve Campbell on February 17, 2002 10:15:28 UTC

I have recently made a breakthrough, i have discovered a way to completely fuse a rib structure between a faceplate/backplate, the rib joints will actually fuse completely, about a year ago i researched casting blanks, this was a ridiculous idea, economically unfeasible,complex and time consumming.
The only thing im concerned about is the particular rib geometry, in particular the stiffness under gravitational stress, trying to
locate a usefull finite analysis modeling program so i can analize the theoretical deformation of this particular architecture.
I predict in the near future atm's will move
away from the solid blanks and begin to realize
the fused cellular design is superior, performance wise as well as economically.
I have also discovered there is indeed a conspiracy between certain pyrex corning distributers and certain well known companys who sell telescopes to atm's, thats ok i found a way around this problem, consider this: the steward mirror lab in tucson(u of a)has made an 8.4 meter blank with a faceplate thickness of 1"!, what this means is its very possible to get by with less than 1/4" thickness face/back/rib thickness for our tiny little 20-30 inch mirrors the trick is to have the entire structure completely fused.
alot of atm's cannot afford to spend thousands on a 6 to 1 blank in the 20+inch range so we improvise and use thin pyrex or soda lime and 18 point floatation cells to support this peice of sh*t, this is not the way to go!.
If your happy with a 6" newtonian, more power to you, but im not and i have found that most atm's lose interest and eventually want to move up to bigger and better things.
To my knowledge only hextek currently offers
blanks which are completely fused structures, the
problem with them is the price.
a fused mirror has advantages,
2)less weight/mass=less thermal absorbtion/less thermal equilibration time.
3)lower cost due to less substrate material.
4)slumping of blank over convex ceramic tooling can be done concurrently with fuzing, reducing grinding time and abrasive cost.
5)annealing will be precision quality, if done properly there will be no question about it.

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