From: "mommoteandcoyote" 
To: 
Reply-To: "mommoteandcoyote" 


Michael,

My experience with the wire test is with a wire, .0025" in diameter,
stretched vertically, dead center over a 1/8" hole drilled through a
piece of .040" thick brass.  The .0015" pinhole is located
1/4" below the center of the "wire" aperture.  The tests
sensitivity  is enhanced, or detracted from based on the size relationship
of the wire diameter to the diameter of the pinhole.  In other words, if
the pinhole is the same size or larger than the wire the wires shadow gets
lost in the diffraction as does any clear zonal identification.  If the
wire is too much larger than the pinhole the sensitivity is lost in the
shadow and the test becomes the same as a Foucault test.

When you view the wire under test, each side*is* the mirror of the other.
As long as you are consistent  with where you place the wires shadow in
relationship to the pins there should be no problem.

I can only assume that the lateral test is the above with the wire placed
horizontally... is that correct?


Coyot‚




Talk with you soon,
Coyot‚
----- Original Message -----
From: "Michael Lindner" 
To: 
Sent: Tuesday, January 21, 2003 9:47 AM Subject: Wire Tests (was Re: ATM
Robo-foucalt...is it calibrated?)


>
> John Sherman (via Nils Olof Carlin) wrote:
> > > My understanding is that Francis derived the test from the Gaviola
> ...
>
> When I originally mentioned the wire test, I was talking about the
> "transverse" wire test, which I have read about in
"Optical Shop Testing",
> and in an old TM article. I haven't seen any information on the
"lateral"
> wire test, although a search through Google and the ATM archives leads me
to
> references to a web page with a general description.
>
> First off, can someone recommend some good references for either/both of
these
> tests?
>
> Secondly, am I correect in assuming that the LWT, being essentially a
"single
> wire ronchi grating", one is measuring/comparing the shape of the image of
> the wire, or just its position?
>
> --
> Michael Lindner
> ATM Site http://www.atmsite.org        TM Web Ring
> http://www.crickrock.com/cgi-bin/webring/list.pl?ringid=TelescopeMaking
> ATM Mailing List (FAQ at http://home.attbi.com/~dcass/atmfaq/atm-faq.htm)
>
>

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