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RE: Flexing A Sphere Into A Parabola

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Posted by Marc on October 5, 2000 16:55:52 UTC

Pete,

I read the article...

Some mirror makers on this forum have years of experience and have produced a pile of mirrors
without having to warp them. That`s fine. But what about the beginner who only wants 1 mirror and does not want to spend years (owing to time, cost, etc) perfecting their glass pushing skills by making more than 1 mirror?

I have seen a number of beginner mirror makers produce a nice smooth sphere and then turn it into a poor surface and call it done ("I worked this mirror long enough" is a common excuse) because they had limited skills with figuring strokes and testing. If the maker had just left the surface spherical and used the technique described in the article, the scope would have certainly performed better. Testing for a sphere is easy compared to a parabola and no complex testing equipment/skills are required. A very simple Ronchi tester is all thatís needed.

If you are a beginner mirror maker and have polished a mirror to a nice sphere and donít think
you can or want to parabolize it, I would explore this option further. If it doesnít work, you can
always remove the backing.

Marc

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