Re: polarizing microscope for the refractive index calculation

"Repeating Decimal" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> in article [EMAIL PROTECTED], George at
> [EMAIL PROTECTED] wrote on 12/1/03 11:52 AM:
>
> >
> > "tzavalas" <[EMAIL PROTECTED]> wrote in message
> > news:[EMAIL PROTECTED]
> >> Hello everybody, i´m spiros from greece.
> >>
> >> I´m taking a course on polymer science and recently I heard that the
> >> non-isotropic substances are not bound to have the same rerfactive
> >> index on all directions. So in the most general case every a sample
> >> bears 2 vertical and one parallel reflactive index. The parallel or
> >> vertical dirctions are regarded in relation to an axis of orientation
> >> of specific groups, like liquid crystals, polymer chains, fibres or
> >> even bonds between atoms etc(which are in the sample and whose
> >> "preference" for a direction is what causes the sample to be
> >> "non-isotropic.")
> >>
> >> So  in my case, where I have a stretched polymer film, I guess the
> >> same thing is taking place. I know that I can use a polarizing
> >> microscope to calculate the values of the refractive index as the
> >> incident (planar-polarized) on the sample light rotates.
> >>
> >> BUT I DONT KNOW HOW?????????????
> >>
> >> thanks in advance, spiros tzavalas.
> >
> >
> > It is not an easy subject to learn.  It is even more difficult to teach.
> > There are several good books on the market on optical mineralogy.  I
would
> > suggest the following:
> >
> > Optical Mineralogy: Principles and Practice. Gribble, F., & Hall, A.,
1992.
> > UCL Press, 302pp.
> > Major References: 1- Optical Mineralogy, Kerr, P., 1977. McGraw Hill,
442
> > pp. 2- Mineral Optics: Principles and Techniques. Phillips, W.R., 1971.
W.H.
> > Freeman & Comp.
> > 3- Student Guidebook for the minerals under the Microscope. Nasir, S.,
1997.
> > Colored Manual of Minerals under the Microscope.
> >
> > Good luck.
> >
> >
> Let me add a bit.
>
> Expression such as "2 vertical and one parallel reflactive index" are
almost
> meaningless. There will be ordinary and extraordinary indexes. The
meanings
> of these are developed in Born and Wolf, for example.
>
> While the concepts are clear for crystals (pure minerals), they will
> probably fail for polymers. Polarizations effects in them are more likely
to
> depend on induced birefringence from stress and strain.
>
> Bill
>

Good point.