Re: [ATM] Dumb Question: how to measure a...

["Greg Jones" <gregj888@comcast.net>]

I guess the first question I would ask is why?

If you are looking at a glass blank, round to a few millimeters is enough and the turn table or measuring diameters and eye will do that.  If you have another need with greater precision, the discussion gives the practical options.  The turntable/lathe should get you to better than .001" up to about 30" Dia without a lot of trouble.  After that you need to ask someone with more experience.  Note, even at this level thermal properties may become an issue.

If you have a finished optic, say the secondary of a classical cassegrain, then you need the optical center and that's a different question.  In this case the center of figure needs to be found.  Please refer to "Reflecting Telescope Optics" for test methods...


Greg Jones
http://home.comcast.net/~dac20/dac_001.htm
_______________________________________________
ATM mailing list http://www.atmlist.net/