[ATM] Box Beam Mirror Blank

[Michael Wheatley <atmwheatley@telus.net>]

I have not found any info on this idea despite searching the 
archives, so if anyone could tell me what this would be called so I 
can search further or why it will not work that would be great.

This idea comes from the info on thin slump formed mirrors and 
interest in a light bucket for occultation.  No fine images would be 
expected.  I would just want as much light as possible from one star 
on the CCD of a video camera mounted at prime focus.  Size 
limitations would be what fits in the back of an old Volvo wagon and 
what I can lift.

I would;

-  form a refractory slurry on a turntable at f2 or f3, possibly as 
large as 34" in diameter,
-  slump a 1/4" plate into the form,
-  build a conformal support on the inside of what is now a mirror blank,
-  remove the refractory form from the back and using vacuum epoxy, 
build a rectangular lattice using more of the same 1/4" plate on the 
back of the mirror blank, say 4" centers and 5" thick, with 2" holes 
throughout for lightening
-  glue a flat plate on the back, also with lots of 2"holes,
-  then the mirror grinding would begin.

That should result in a mirror with the weight of a 3/4" blank and 
the stiffness of a 5" blank.  The mirror surface would have support 
every 4" from the attached box.  I would hope for three point support 
at the back plate with counterbalances at each side that take all the 
weight of the mirror regardless of telescope altitude.  If I can't 
lift the weight of a 3/4"x34" blank it would all have to be smaller.

I am not saying this is a good idea but I hope it is an interesting 
one.   Mike Wheatley

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