plh wrote:
Hello, people of sci.astro.amateur,
I am working on an independent study project that involves making a
small telescopic mirror. The professor's idea is to turn the mirror
out of aluminum or perhaps stainless. We have access to CNC machinery
and can turn a parabola according to a formula within accuracy of
+/-.0005". The blank will be about 2" diameter. Then we would grind
and lap it, then platinum plate through deposition.
My question to the good people of this group is, does this sound
feasible? This project is not for looking at stars. It has to do with
creating special eyeglasses. Once finished, a small rectangular
section will be removed then embedded in the eyeglass lens. But I am
not here to debate the pros or cons of that part of it. It is the
mirror part I was looking for feed back on, or for leads about which
sources of information might be helpful.

Thank You,
-plh

You gotta love it when professors reinvent the wheel for the Nth time.
Diamond turned freeform molds for eyeglasses are common in industry.
Companies such as Optical Electroforming specialize in this type of
work. http://www.opticalelectroforming.com...d/diamond.html
The molds are turned in electroless nickel and have an off the machine
form accuracy of about +/- 0.000001". The form of these molds does not
have to be rotationally symmetric, and in fact these machines are used
to produce torics, bifocals, and progressive prescriptions.

BTW, stainless cannot be diamond turned. The iron in steel has an
affinity for the carbon in the diamond tool.

--
jeff