Difference between O and E rays to S and P polarizations

[CGandC]

The problem relates to birefringence and crystal optics.

What is the difference between O and E rays to S and P polarizations?
Is O-ray just a different name to S-polarization and E-ray a different name to P-polarization? if not, what is the difference?-

 

[Ibix]

It's been a while since I studied this, so do be aware that this is my rather hazy memory.

Imagine a beam of polarised light incident on the surface of a birefringent crystal. You can look at the polarisation of the light and compare it to the optical axis of the crystal, and say that the light is in the S or P polarisation, or somewhere between. But it's neither the ordinary nor extraordinary ray - that distinction doesn't arise until the beam strikes the crystal and splits into two.

So light in the O ray is S polarised and light in the E ray is P polarised (I think I got that the right way round). The input light may be meaningfully said to be S or P polarised or in between, but it is neither the O ray nor the E ray.

It's just jargon, anyway. I'd say that, if in doubt, specify the relationship between the polarisation vector and the optic axes and don't worry about the labels.