Re: Another polarization question

On Fri, 28 Dec 2007, Fleetie wrote:

Thank-you for your gracious responses.

My reply was based on an assumption that the "iodine" chains
in the plastic film are exactly analogous to the wires in the wire
mesh polarisers, given that the article seems to say that electrons
are free to travel along those chains but not between them.

Beyond that, I'm completely in the dark, so I too would appreciate
clarification from someone who knows.

That would be about right. With a classical picture, you need conductivity to get absorption, and to get polarisation dependent absorption, you need a direction-dependent conductivity. So analogous to wire grid polarisers, except that wire grid polarisers might reflect rather than absorb - it's a question of how high the conductivity is.

A fuller story might need to include some quantum mechanics, since you're talking about molecules.

A related question is why stretched polymer sheets are birefringent, and you can answer this in terms of individual molecules possessing "shape birefringence" or "form birefringence".

--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://eprint.uq.edu.au/view/person/Nieminen,_Timo_A..html
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html

.