Re: If a photon has polarization.

["John S. Denker" <jsd@MONMOUTH.COM>]

Qiang Lu wrote:
> one can not say that a photon has polarization.

Really???  Why not?

> Spin is the property of photon to substitute polariztion in the field theory.

I wouldn't have said that.
1) The quantum description is correct.
2) Field theory is not the opposite of classical.
   We have classical fields and quantum fields.
3) In QM, the angular momenum is quantized.
4) In the classical limit, the field has angular momentum, but
   we ignore the quantization thereof because the scale of
   the momentum is so large compared to the size of the quantum.
5) Linear polarization can always be re-expressed in terms of
   circular polarization (and vice versa) by a change of basis.

> The polarization foils in 2 tube
> are parallel, while the polarization foils in 3 tube are vertical. 'Parallel' means
> the parallel of polarization, the same of 'vertical'.

I can't parse that.
If parallel means the same as vertical, then what's the difference
between tube 2 (parallel) and tube 3 (vertical)??????

In any case:
 -- If you have crossed polarizers, nothing gets through.
 -- If the polarizers are aligned with each other, then anything that
gets through the first one gets through the rest.  (We are assuming
ideal polarizers held at temperature=0, ideal detectors, et cetera.)

Also:  half the photons from a black-body source will get through the
first polarizer.  This is true for linear polarizers and equally
true for circular polarizers.