Re: [ATM] RE:anealing

["Bob May" <bobmay@nethere.com>]

Scott, I'm kind of lost in space with your post!
How is it that a parabola is the only surface that doesn't show a toroid
shape?  Any off-axis aspheric will show not that it is a toroid but rather
that it is an odd durface.  The paraboloid is only an artificial point along
the scale of the oddity as you go along the shape of the surface.
When you try to test an off-axis surface of any shape, you have to take into
consideration that you are indeed looking at a part of the whole surface of
a figure of revolution or you will end up with all kinds of wierdness in the
surface shape.  Align the surface so that it produces a particular direction
of the offset of the surface to the figure of revolution and you can only
test as a 1D surface shape and that is only what the Foucault test does
although you can rotate the surface and gain further info in other
directions, unlike the off-axis shape which will obviouusly show a different
shape in different orientations.
I really haven't played with an off-axis surface with an interfrometer but
I'd suspect that you can't obtain a result of the surface unless you use a
compensator of some kind to return an image that is the spherical wavefront
of the surface.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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