Re: [ATM] conic constant

["Bob May" <rmay@nethere.com>]

Ah, eccenctity, Conic constant and other such things.  Kind of
like the fun that you get into when defining directions in optics
as it seems evrybody that wrote a book on the subject has a
different idea of what direction is which!  Not only that, but
how do you measure the distance from one surface to the next?  Do
you measure it from the beginning of the optical path or do you
measure each distance individually and eventually sum them up to
find the total lentth of the optical system?
This much I do know which is that the conic constant is the
negative of the square of the eccenctricy or CC = -sqr(-e).  It
ends up that a sphere is 0, a parabola is -1 for the CC.  The fun
begins when you want to define a surface that is oblate (i.e. the
side of an ellipse) with the conic constant.  My Optics Lab
program refuses to make an obblate surface when the numbrts are
put in and will swap the two focuses if they are in the wrong
order.  It also has a Schwartzchild Constant entry which you can
do instead and that also doesn't allow the oblate ellipse to be
generated.
JUST WISH THAT THE POMPOUS NITWITS WOULD USE THE SAME
LANGUAGE!!!!!!!!
Somebody that is a lot more mathmatecallhy inclined than me
should probably do a small article on the various methods of
expressing the shape of the surface and why the particular method
was chosen.  Also include how to generate the various numbers.
Bob May
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