ATM Ellipsoid or hyperboloid? or maybe paraboloid?

[Bob Prabowo <BOB@bahana.co.id>]

Guys,

After a lot of consideration I decided to continue with the focal length
I have because Newt and  Jim's telescope planner showed me that I still
can use 1.83" secondary on an f/5.39. Boy, am I glad :-)

Anyway, last night after a polishing session I tested my mirror again.
So far I've done 9 hours of polishing the last 2 hours were done with
1/3 stroke (the right one), alternately MOT and TOT (an hour each).

When the KE cut the beam at COC the image that I saw looked like the
image of ellipsoid or hyperboloid or paraboloid, I don't know which one
it is but according to the picture in Sam's book it's either one of
those.

So far I haven't taken any measurement because what I want to do is to
concentrate on the appearance of the mirror on Foucault test and Ronchi
test.

My questions:
1. How do I tel if my mirror is ellipsoid or hyperboloid or paraboloid?
2. I plan to continue polishing with 1/3 stroke for another two hours to
get a sphere, is it correct?
3. Should I start figuring instead of keep on polishing?
4. I made a Ronchi grating using a monofilament but the monofilament I
have is a clear one (no color) should I get an opague one or should I
blackened the one that I've made?

Thanks,
Bob P. Sumitro
Jakarta, Indonesia

visit my still-under-construction astronomy and telescope making page:
http://www.geocities.com/CapeCanaveral/Hall/2670/