Circular polarization through a linear polarizer

[groopion1]

Hi
I have a question about a circularly polarized wave.
Once this wave passes through a linear polarizer - how is the wave intensity changed?
Someone has told me that the intensity decreases to its half value, but I’ve read somewhere the intensity is not changed…
So… what is the answer and why?
Thank u!

 

[Born2bwire]

It decreases by half. You can decompose a circularly polarized wave into the summation of two linear polarizations at normal directions (but with different phase of 90 degrees). Align the polarizer with one of the linear polarizations and you can see that you lose one of the polarizations. Since the way you decompose the wave is arbitrary, this is valid for all orientations of the polarizer.