Re: [ATM] Card in the foucault test

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

The purpose that the paper has is to guide you to the proper alignment of
the test.  When the light return goes past the KE, cutting off some of that
beam by the KE, you will see shadows on the mirror's surface of what you are
tending to indicate.  When you are far from the ROC of the mirror, the KE's
shadow will proceed from one side to the other - same direction being inside
the ROC and opposite being outside the ROC - while the KE being within the
range of ROCs of the surface of the mirror produce various shapes.  It
sounds to me like you're in the right range of ROC values to start seeing
what the mirror's shape is.  There's a fair number of images and drawings of
mirror shapes on the web at the various sites showing off mirrors and so
forth which will help you see the shape of a mirror.  Please note that only
when you have actually measured the ROC changes with radius from the center
of the mirror can you actually tell if you have a parabola or not.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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