Re: [ATM] slow polishiing

["Jerry B. Hillman" <JBHillman@ev1.net>]

Hi Bill,
For a mirror that small you seem to be spending a lot of time polishing it.
I have heard stories of the experts doing a mirror that size in a single day
at Stellafane. But, for your problem, When you are polishing, do you have a
lot of resistance, or is the lap floating on the CEO/water mixture.  If it
is the latter, then you are using too much CEO mix.  For instance, on my
16.5" mirror, when I was polishing, I would use about three drops of CEO
water mix at a time, and then would polish until resistance between the lap
and the mirror increased until I could almost not move the lap, then I would
add another three or four drops.  Polishing is most effective when the
mirror is almost, but not quite dry, and there is a LOT of resistance.  No
resistance, no polishing is happening.
In the Foucault image you posted, the central depression seems to be
irregular.  The experts need to check me on this but I think you have some
major astigmatism building there.  I won't even begin to pretend I
understand how the Ronchi image you posted was formed. I have never seen
anything like it.  I hope the real optics experts take a look.
Clear skies, Jerry


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