# Wave Plates

1. Nov 16, 2009

### raisin_raisin

Hello,
I am trying to figure out how the electric field changes before and after passing through a waveplate but my notes don't make any sense.
I think
Eextin=Ecos$$\theta$$ and Eordin=Esin$$\theta$$
where theta is the angle the electric field makes with the optic axis.

I can't tell how the amplitude changes on Eout though.

I know they pick up a relative phase but I can't tell if this is in addition to a phase anyway.

i.e is it just
Eextin=Ecos$$\theta$$
and Eordin=Esin$$\theta$$ ei$$\Delta\varphi$$

or if it should be the same but with a different amplitude i.e E' not E afterwards (in which case how do I calculate this?) or whether it should be

Eextout=Ecos$$\theta$$ei$$\varphi$$e
and Eordout=Esin$$\theta$$ ei$$\varphi$$oei$$\Delta\varphi$$

Or should it be this with E' instead of E?
This is what my notes suggest but I am hoping it is wrong since delta phi is $$\pi$$ so it would make it easier if it wasn't.

Thanks for any help.

2. Nov 17, 2009

### Redbelly98

Staff Emeritus
Assuming no absorption or reflective losses, Eext and Eord keep the same amplitudes. They do get a relative phase shift, so just tack on a factor exp(iφ) to one of the amplitudes as you had originally.

Yes, there is an overall phase as well, but that is not important as it does not affect the amplitude or polarization of the output wave.