[ATM] plop auto cell 36 and 54 points with very thin mirrors

["astroguy@nas.com" <astroguy@nas.com>]

The 54 point PLOP design came up several years ago when I requested the
need for such a design.  At that point in my life i was exploring the
feasability of making thin mirrors with equal thickness by slumping the
glass prior to fabrication.  I had some successes (2-14") and failures
(26"), the financial and emotional loss of the 26" slumped blank due to
fracturing even though it was very well annealed slowed my efforts
considerably.

I am convinced there is a place in the ATM hobby for thin slumped mirrors
and multi point support systems. I made up a 54 point cell for a 32" blank
based on a non PLOP design. The support system was EASY to design and
fabricate, and there is no doubt in my mind that it would work excellently
with a well figured mirror. 54 points might seem over-kill but with a thin
mirror, I dont think so.  

The ultimate goal was to slump and mount the 32" blank and use the lessons
learned to slump, fabricate and mount the 46" blank also sitting in my
shop.  Both blanks are 1" thickness.  YES, only one inch.  The only reason
I use 1" is because that is what was available to me.

Ultimately I envision ATM's using computer controlled actuated mirror
supports to compensate for the thin optics and very big glass.  There are a
few ATM's that are serious to make 60" and larger scopes.  Thin glass will
be ONE part of the solution to such large and possibly portable
instruments. These projects are worth the efforts involved and will open up
new vistas for ATM.

The unslumped glass blanks now in my shop are available free to any
individual who is serious to take on such projects. Cant remember all the
sizes, I think 32", 38" and a 46".  This type of project most likely will
require the efforts of many individuals, with many different skills and
educational backgrounds to be sucesfull.


Kreig McBride
Bellingham, WA


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