Re: [ATM] A more or less new optical test

[Nils Olof Carlin <nilsolof.carlin@telia.com>]

Mike,

the moderate amount of not too deep math is a bit deep for me - can't 
be helped (at my age). The eliminating of difficult boundary conditions 
by cutting away the boundary seems very creative to me.... All in all 
an interesting approach. One thing I wonder is if it is possible to 
make a graded transmission filter that does not introduce untoward 
phase shifts - it might be possible, I don't know if the test is very 
sensitive to such things. 
I can imagine some similarities (not too many) with MRI images - the 
creative use of varying gradients in three dimensions to spatially map 
the object, and the Fourier transform to compute the image.

But browsing the text 2-3 times, not too closely, I fail to see what 
you refer to about the geometric treatment of the Foucault test.

The whole idea seems very appealing - wonder if anyone can make it 
work in real life?

Nils Olof

For anyone interested in non-interferometric optical tests that might 
be amateur friendly a preprint just showed up on the arxiv discussing 
a form of generalized Foucault test using variable transmission 
filters. Here's the link to the pdf: 
<http://www.arxiv.org/ftp/physics/papers/0510/0510224.pdf>.

The paper is strictly theoretical with a moderate amount of not too 
deep math and some numerical simulations. The author claims this 
Foucault like test is capable of accuracy comparable to phase 
shifting interferometry or a Shack-Hartmann test. That's based solely 
on a limited set of numerical simulations though, not real world data.

Nils Olof might be interested to see that he gives a partial answer 
to the question of why and when a geometric optics treatment of 
Foucault test data works despite the fact that the intensity 
distribution in the shadowgram is governed by physical optics.

Mike Peck




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