Re: [ATM] Building Foucault tester

["Marc J. Sibilia" <msibilia@ailr.com>]

Here is a picture my very easy to make, cheap, very functional foucault tester.

<http://mysite.verizon.net/vzeeegvr/micro_foucault.jpg>http://mysite.verizon.net/vzeeegvr/micro_foucault.jpg

The Chinese are building great precision foucault testers for us for 
peanuts. It uses a single $8 micrometer as the measuring element, the 
longitudinal stage and the transverse stage.

The hardened micrometer rod rides in a non-critical alumium V-groove (it 
could be wood), the carbide face bears on a razor blade stop (could be a 
steel ball), and the back of the barrel rides in a plastic (scrap vinyl 
siding) V-groove (could also be wood).

A tapped hole and screw with a knob raises and lowers the end of the 6 inch 
side arm to tip the blade in and out transversely. The only modification I 
might make is to add some teflon on the baseplate under the tipping screw. 
The arm is attached with a screw through the C of the micrometer using one 
of the holes for the plastic heat shields. The same screw also mounts the 
wood block that holds the LED and the slit and analyzer blades. I like the 
slit to limit the amount of distracting reflection off the back of the 
mirror, but it would work as a slitless. The rubber band holds the 
micrometer face against the stop (could be a spring).

I use a camera and a TV with mine which I have to say makes everything 
about testing so much easier with no squatting and squinting as well as 
faster and more precise. With the enhanced contrast available, there is 
much less judgement involved.


Marc Sibilia  

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