Re: A stinking explanation ?

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

I will think about what John wrote. Meanwhile here are two
quick clarifications.

John Mallinckrodt wrote:

> This may be technically true, but I think it is a little misleading.
> To consider a wave "extraordinary" it must have at least some
> component of its E-field parallel to the optic axis.  (I am restricting
> my consideration to uniaxial substances like quartz.)  If a wave
> propagates along the optic axis, then both linear polarizations are
> necessarily identical in every respect.

Why do you think a parallel component of E is necessary?
The E-wave is polarized in the principal plane while the
O-wave is polarized perpendicularly to the E-wave. In that
way they are not identical. I am also considering uniaxial
crystals only.

> > Consider a quartz plate whose optical axes are
>
> (?? I assume you mean to say "whose optical axis is")
>
> > also normal to its flat surfaces. ...

The plural was intentional. Any axis parallel to an optical
axis is also an axis. In crystallography an axis is a direction,
not a unique line, as for the axis of rotation. This is not
essential here, we can say "axis", if you prefer.
Ludwik Kowalski