Re: SEM follow-on question

[T3D John Bercovitz <bercov@xxxxxxxxxx>]

Thanks Ted for the complete description; now I've got a clearer understanding.
Thanks George for the clear, intuitive and I believe accurately-concluded post.

John Vala writes:
>    What I am trying to stress here is that we can't take what we know about
> conventional optics and stereography and try to apply it to SEM stereography.

I think we can possibly make it look in one way like a conventional optics
problem.  Here's how:  The tiny beam leaves the source and is rastered over
the sample.  If the beam actually flowed in the opposite direction, we'd see 
it is very like an object's photons passing through the entrance pupil of a 
camera lens.  So I think the problem is like a lens and from what I understand, 
it is often a very long lens and so John Roberts' drawings, which are on the
Tech3D web page which Joel Alpers made for us, represent the actual situation 
we're dealing with here.  John R shows a very long lens focal length and that
would be the basis of saying that the images are near-orthogonal projections.
So it's a matter of degree: we do have toe-in distortion but it is small
because of the excessive focal length/specimen size ratio.

If not, why not?

Thanks,
John

PS to GAT: You can change to ACK any time or I can change you.  No one has
to be in digest mode if they don't want to be.  Also, this is a small list,
(50?) so if anyone wants ACK and DIGEST, just let me know and I'll hack the
subs list to make it so.

Oops!  I went over the 75-column line limit!  My apologies.  8-(


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