Re: ATM Pictures of mirror surface showing pits

["Bob May" <bobmay@nethere.com>]

That picture of the 6" further down the page shows the Twyman effect to good
effect!  A nice little raising of the broken edge is what Twyman described
as to what happens when you cut or otherwise disturb a finished optic.  A
few cuts with a lap will quickly take that down without too much trouble.
The pits look exactly right.  They are all kinds of little cracks that
happen when the grit digs into the glass.  The next little bit of fun will
be to follow the pits down through the grits, the AlO grits make a different
kind of pit, and through the polishing stages.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net