Re: [ATM] Standing Under Foo-co

["David Harbour" <scarab2@cox.net>]

Jerry,

My very widely read article "Understanding Foucault" is here:

http://www.atmsite.org/contrib/Harbour/Foucault.html

I know that Micheal Lindner can steer you to some excellent pictures of
different testers. The important thing is to make one edge of one razor
blade (lower half) one of the jaws of the slit, and extending upwards the
other half makes the knife edge. This is a neat way to make sure that the
slit and knife edge are parallel; mount the other razor blade lower down for
the other side of the slit. Any Foucault tester made this way works as BOTH
a slit equipped tester, and a slitless tester. As the knife edge is advanced
in laterally from the side (left, preferably) as soon as the aerial image of
the slit shows the jaws with a smaller (smaller gap) than they really, then
the slit equipped tester is functioning as a slitless tester. To see mine,
go here:

http://www.atmsite.org/contrib/Harbour/Tester.html

Although I machined the parts to mine, it is to build a tester with just as
precise movements like mine, WITHOUT any machining. Instead of the four
lathe turned "nose cones" one may easily cut out of aluminimum angle stock,
two little "V" notched cradles for both X and Y movements (wrap a thin shim
of brass over each inside edge of the "Vs")

And make sure to ask Michael for some links to some pictures of other
testers.

The pictures that show my tester will all enlarge if you click on them. The
razor blades were located on the back side of the bar, the slit with a light
behind it, below, and one of the blades extending half again its length
above the slit, for your knife edge. Two holes, one right above the other,
provide apertures for both the slit, and the knife edge (razor blade edge).
I made the left blade extend upwards, covering both holes, for the left jaw
of the slit, and on up for the left hand sided knife (razor) edge. The right
hand razor blade was epoxied down lower, so that it did not extend up, but
only formed the other jaw of the slit. (with light source behind it)- you
can see the little black box built on the back side of this vertitical bar.

Dave

----- Original Message ----- 
From: "Jerry" <jldove1@cableone.net>
To: "David Harbour" <scarab2@cox.net>
Sent: Monday, May 16, 2005 10:53 PM
Subject: Re: [ATM] Standing Under Foo-co


On Mon, 16 May 2005 19:18:26 -0500, you wrote:

David,

May I ask where your paper is posted?  I'm close to having to start testing
my blank and I'm at a loss as to how
this works. I've made a tester that I hope will work, but I was told by
someone they didn't think it would work as is.
Anyway, any help would be greatly appreciated.

Thanks,
Jerry

> I wanted more amateurs to use Foucault, and I knew the
>main reason they didn't is because they didn't understand it on an
>"intuitive" level- but I KNEW (since I had taught myself) that I could
>explain it in a more lucid manner than others had. So in 1995 I started
>writing and illustrating "Understanding Foucault".



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