What is polarization of light?
I am not able to attach the drawings to illustrate this. i am giving this note in my profile.
Polarization is an important experimentally observed property of light that had been
ignored in physics. It cannot be dealt with by mathematics.
Polarization is important because it shows the presence of chiral components in light.
Quantum Mechanics cannot accept the presence of chiral components because chirality
cannot be dealt with mathematically.
Polarization had been misunderstood by early wave-theorists.
In essence polarization phenomenon proves the existence of chiral components in light.
This is anathema to Quantum Mechanics.
Light is “polarized” when it is passed through a Nicol Prism. Nicol prism is a transparent
calcite (Calcium Carbonate) crystal cut in a particular fashion. Three beams exit from the
prism. The first is the original ray slightly refracted beam as in other transparent media
like glass. This is not polarized.
Two other beams emerge in orthogonal planes. Both are polarized in opposite senses.
One beam is in the plane of paper or parallel to it and the other is in a plane perpendicular
to it. The second beam gives rise to two images of a dot under the prism. (This is what is
called “double refraction or birefringence).
There is a Wikipedia section on birefringence.
The polarization along the orthogonal or perpendicular plane to paper is called plane
polarization. (In the wave theory plane polarization meant arranging/ordering the waves
in all planes into a single plane called the plane of polarization.)
Wave theory ties itself in knots to explain the presence of two chiral beams in what is
called circular polarization. The light wave itself is said to be rotated in a helical fashion
either right-handed or left-handed. Thus the two beams observed in circular polarization
become an artifact of the instrument.
It is our view that the two beams are originally present in light. Polarization separates the
two beams. In plane polarization only one beam is studied and in circular polarization
both beams are brought into the same field of observation.
A B C
Fig. A shows the chiral components of light in red and in blue. They are chiral to each
B shows the arrangement of the Nicol prism in plane polarization. The red beam is
allowed through. The blue beam is blocked.
In “circular” polarization the two beams are arranged at an angle of 45° to the
arrangement in B by a “quarter wave” plate. It rotates the arrangement of the beams in B
by 45°. This enables both beams to be observed serially.
C shows the Nicol in circular polarization. Left ward rotation of the Nicol by 45° would
allow the red beam to pass through, blocking the blue beam. Rightward rotation of the
Niol by 45° would allow the blue beam through but block the red beam.
In a system with multiple chiral centers the two beams would be rotated to different
degrees, a resultant of different rotations by the multiple centers. The difference between
the rotations of the two beams is known as circular dichroism.
The important point to note is that there is nothing “circular” in circular polarization.
In plane polarization only one beam is used for the study. In the other, both beams are
Anisotropy in polarized light absorption is designated linear di-chroism which is a
misnomer. (The prefix ‘di’ indicates two.)