Measuring the Polarisation of Light

[Miss_Astro]

Maybe this is a trivial question, I'm not sure, but when you measure linearly polarised light, such as that in the CMB which component of the light is 'measured'.

By this I mean is it the oscillating electric field or the oscillating magnetic field that is oscillating in the direction of the polarising filter. Of course the E and B fields (not to be confused with E and B modes) cannot occur independently as it is an 'Electromagnetic wave' but as they are perpendicular the polarising filter can then only lie in the direction of the oscillations of one of the components.

 

[nickjer]

Please read http://en.wikipedia.org/wiki/Polarizer

If you are talking about Polaroid films, then you might be interested in the 6th paragraph in the section called "Absorptive polarizers"