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On 26 Jan 2006 at 1:24, Bill wrote:

> One more question, Just how the h-ll can that work? Please elucidate me/us.

I don't know of a good mechanical analogy other than to just state that
the polarizer introduced inbetween the crossed polarizers (which is
oriented so that it's not at 90? to either of the others) rotates the
plane of polarization so that it's no longer at 90? when it now hits the
3rd polarizer, so some light passes through. To see how this happens you
really have to do the math. I guess the important part to consider is that
light is an electromagnetic wave (i.e. there is an electric component and
a magnetic component) so it is a mistake to just consider the electric
component that passes through the first polarizer as being confined to a
bunch of parallel planes. There is also the magnetic component which is
orthogonal so it's better to think of the two components together. It's
the interaction of this complex with the oblique polarizer in the center
that rotates the plane of polarization away from the original orientation.

I'm afraid there's just no good way to think of light in terms of objects
with which we are familiar. Even the phycisist Richard Feynman, who knew
as much about light as anyone, visualized light as invisible angels.

Ken Muldrew.

   

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