Re: [ATM] A bit of hand polishing advice please................

["Jerry" <wa4guu@verizon.net>]

True in most cases. But.....


It really doesn't matter which side the source is on. It is which side of
the returning beam the knife cuts. My tester has a moving slit source and
fixed knife.  I am right eyed for testing purposes.  I shaped the lamp
housing to clear my head on the right side... just barely. But I still like
the knife to cut from the right, because that is the way I am used to
interpreting the shadows. So I made the knife thin so the slit can get very
close to the back side of the knife.  Even though the slit is to the right,
the knife edge is on the left of the knife, so for interpretation I view the
surface as thought the light is grazing from the left.

I can get my slit to about 3/8" of the knife with them laterally in line and
still get my eye to the knife. If I wanted to get closer I could turn the
knife around and get them about 1/8" closer. But then I would have to shoot
for an oblate to get a parabola.

Jerry

-----Original Message-----
From: Mark Holm
 
Looks like TDE to me.  I use the old mental dodge of thinking of the
light crossing the mirror at a grazing angle from the source side to the
knife edge side.  It helps decide the "sense" or slope of the shadows,
up or down.



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