ATM Lateral Wire Test

["Bob Walker" <tac@i1.net>]

I have read about the Lateral Wire Test with some interest, since I have
some trouble being sure what I'm seeing with the Foucaul and Ronchi tests.
Between the two, I think I'm getting valid results, but the uncertanty is
greater than I would like.  The lateral wire test seemed a good alternative,
so I looked up what I could find in the Archives, and downloaded some pages
from the LWT website.  I tried using the LWT, but the images were so dim and
indistinct that I think I must have done something wrong.  The way I set up
the test apparatus was by using my Foucault/Ronchi tester.  It has  moving
source, a 3/16" diameter blue LED with a very simple clip in front of it
into which I can slip either a Ronchi grating or a carefully lapped utility
knife blade for a slitless Foucault tester.  What I did was grind away the
edge of a utility knife blade until it was shaped sort of like a C, and glue
a very thin (.004") wire across where the cutting edge used to be.  I then
slipped this into my tester with the lower part of the wire extending across
the center of the LED and the upper part rising above it where I ccould look
through it.  Just like a single line on a Ronchi grating.  The results were
much harder to see and much more ambiguous than using a Couder screen.  Did
I do something wrong, or is this test just tough to perform?

 *    Best regards,
*          Bob
         *          *    *

           *         *