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Re: Help Newtons Rings

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Posted by Robert May on April 14, 1998 19:24:35 UTC

Dave, What test are you doing? Is it a Ronchi test against a flat? Or is it a Star Test? Or are you looking through the glass and seeing the far surface? Remember that a parabolic surface can be produced by a spherical tool. The final test on convex surfaces has to be done with something that sees the surface. The easiest testing is probably to assemble the scope and do a double pass test. As far as deciding which is which, go try to take out one of the error directions and see what it produces. That is where you are going. Good Luck with the project. Remember that if concave surface is on top, the radius decreases and viceversa for the other way. Good Luck and Have Fun. Bob May

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