[ATM] some largish thin mirror questions

[dan feldkhun <feldkhun@colorado.edu>]

I'm starting work on a pregenerated 12.5" ultrathin (0.5" at the edge) pyrex mirror.

Mel Bartels recommends doing polishing and figuring MOT to keep particles flaking from the tool,
etc. from scratching the mirror.  I'm concerned that this will cause the surface to warp
significantly due to gravity, hand pressure, etc.  I have a long ways to go until polishing, but I'm
thinking of trying to polish blind under water in a recirculating bath of cerium oxide to keep the
mirror from flexing too much.  Has anyone considered doing something like this?  Am I nuts?  I know
it's a lot of CeO2.

For fine grinding, I poured a plaster tile tool. I was running out of time and decided not to cut
the square tiles to conform to the edges of the mirror and use whole tiles only, leaving large areas
of tile-less plaster near the edges. My thinking was (and still is) that as long as I keep rotating
the mirror and randomize the strokes with the non-circular tile tool, the effect will be the same as
that of a slightly sub-diameter circular tool.  By that logic, one could in principle get away with
a square, triangle, or any arbitrarily-shaped tile tool.  Any reason to keep to a circle?

Dan


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