polarization - Polarization polarizers and polarization...

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Polarization, polarizers and polarization experiment, solid angle Here is, I hope, a better, more intuitive explanation for what is going on when we pass light through polarizer and why we are able to get some light through three polarizers, even when two of them are crossed. I am also including some more detailed information with a nice schematic on polarization from wikipedia. I am also including a little blurb on solid angle, so that hopefully you can visualize and understand the concept a little better. Polarization The simplest manifestation of polarization to visualize is that of a plane wave , which is a good approximation to most light waves (a plane wave is a wave with infinitely long and wide wavefronts). All electromagnetic waves propagating in free space or in a uniform material of infinite extent have electric and magnetic fields perpendicular to the direction of propagation. Conventionally, when considering polarization, the electric field vector is described and the magnetic field is ignored since it is perpendicular to the electric field and proportional to it. The electric field vector may be arbitrarily divided into two perpendicular components labelled x and y (with z indicating the direction of travel). For a simple harmonic wave , where the amplitude of the electric vector varies in a sinusoidal manner, the two components have exactly the same frequency. However, these components have two other defining characteristics that can differ. First, the two components may not have the same amplitude . Second, the two components may not have the same phase , that is they may not reach their maxima and minima at the same time. The shape traced out in a fixed plane by the electric vector as such a plane wave passes over it (a Lissajous figure ), is a description of the polarization state . The following figures show some examples of the evolution of the electric field vector (blue) with time (the vertical axes), along with its x and y components (red/left and green/right), and the path traced by the tip of the vector in the plane (purple):
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This note was uploaded on 03/31/2008 for the course ENGINEERIN EN31 taught by Professor Georgakoudi during the Fall '06 term at Tufts.

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polarization - Polarization polarizers and polarization...

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