Re: Snell (in Calcite)

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

You are correct (see below), the so-called generalized Snell's
law is described in many references. The one I am playing with
is "Handbook of Optics" (Sponsored by Optical Society of America,
edited in 1973 by Walter G. Driscoll. Page 10-25). By the way,
here is what one can read about calcite from this reference.

"Next to quartz, calcite is the most widely distributed of all minerals
and usually occurs in an impure polycrystalline form as marble,
limestone, or chalk. However, optical calcite, or Iceland spar, is
quite rare. Before the twentieth century it came almost entirely from
a cavity in basalt 11 by 4.6 m^2 in area and about 3 m deep, located
by the farm Helgustadir near Reydar Fjordur on the east coast of
Iceland. When first found, the cavity was filled with a pure crystallized
mass containing enormous crystals, some a yard across.

This source is now exhausted, but crystals from it described in detail
by Erasmus Bartholinus in 1669, led to the discovery of the law of
double refraction by Christian Huygens in 1690 and to the discovery
of the polarization of light by Malus in 1808. Optical calcite now
comes principally from Mexico, Africa and Siberia. It has been grown
artificially ....but maximum edge lengths are only 3 to 4 mm."

I also found (in "Concepts of Classical Optics" of Strong, page 111)
a paragraph-long quote from Bartholinus. Good reading.

Mojca Cepic wrote:

> ... For the reference is Born... but there is also another book, which
> is written for technologists and has the two expressions for the angle
> dependence of the refraction index  for the uniaxial crystal with
> optical axes perpendicular and parallel to the surface written
> explicitely. Unfortunately I have to go to the library to find the
> correct reference. Si in a few days.