Re: [ATM] how to use the foucault tester

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

There are several good articles on the web on using a tester, mostly the
theory of what it is doing.
You really still need to build a mirror support, the part of the tester that
is often forgotten about by the people writing articles on constructing the
tester itself.
You really just need a board with two feet on the front and a screw at the
back (I tend to use 1/4-20 all thread with a knob on the top and a wood
insert nut on the bottom of the board) to point the mirror in the vertical
direction.  A second board set vertically with a pair of dowels (use big
enough ones or even a pair of blocks) that are pointed up and towards each
other a few degrees so that the front of the mirror is supported rather than
the back of it (keeps the mirror from falling off of the stand!).
When doing the test, try to get the tester end at least as high as the
center of the mirror so that you don't point the mirror down which will make
the mirror fall off even easier than otherwise.  You also want something
sturdy (and even then you don't want to touch the surface unless absolutely
necessary as the test is indeed very sensitive!) like a concrete floor to do
the test on.
If you have something like a camcorder, you can place it immediately behind
(put the KE on the backside of the stand if possible here) the KE and
actually be able to see the test on your TV set which will make the testing
a lot easier to do.  I also recommend that you make a mask for each zone of
the Couder screen rather than try to use the allzone mask setup that causes
problems with so many people.
Bob May
bobmay@nethere.com
http://nav.to/bobmay
http://bobmay.astronomy.net

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