Topics In Light Polarization

Last updated: Wed Jan 22 2003

Still very sketchy!
but do check out the experiments ...

History

A site with a very nice history of polarization: http://www.polarization.com/history/history.html

Birefringence

The story of polarization begins with "birefringence", a property of some crystals to produce double images.
It indicates the presence of two types of light rays, each one with a different *linear* polarization.

Polarization

Some of the ways of separating one *linear* polarization from the other:
- by reflection (from flat glass or water, for example)
- by scattering (as in the atmosphere, or through milky water)
- by double refraction and redirection of one ray (compound calcite prism)
- by double refraction and absorption of one ray (dichroism, polaroid film)
- by laser action. Laser light is already monochromatic and in phase. In many lasers it is also polarized (naturally or artificially).

The Two States of Light

There are 2 states of light and this is what gives rise to "polarization".
What s the origin of these two states and why are there only two ?
How do these states mix and how can they be measured?
- linear polarization
- circular polarization

Optical Activity of Organic Compounds

Many organic compounds can distinguish the two forms of *circular* polarization of light.
- chiral molecules
- chirality in organic compounds, most (all?) organic amino acids are l-chiral (laevus, left) and many (most?) organic sugars are d-chiral (dexter, right). Some sugars.

Animals Using Polarization (and Plants?)

Examples and experiments ...

Interaction Free Measurements

More advanced: The Illinois Mach-Zender interferometer, (copy). How to use the two level property of light (polarization!) and the quantum Zeno effect to achieve interaction free measurement, most of the time.

Optical Activity due the Weak Force

More advanced: weak force The weak force is known to be fundamentally "polarized". Can this polarization affect electromagnetic radiation (light!)?

Experiments

- calcite crystals and birefringence
- polaroid film
- polarization of daylight scattered by the atmospere (blue sky).
- dark and bright lobes generated by scattering of linearly polarized white light by a water column.
- color helix generated by scattering of linearly polarized white light in sucrose (table sugar), the effect is more pronounced in corn syrup (Karo syrup, dextrose and d-fructose) and produces a mirror image helix in fructose (fruit sugar, l-fructose)
- rotation of polarized monochromatic laser light in corn syrup (Karo syrup)