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Polarization by Transmission Through a Filter:
A Polaroid filter is a device that polarizes light. The filter serves to filter out one-half of the vibrations of unpolarized light as the light passes through the filter. Unpolarized light enters the Polaroid filter and polarized light exits the filter with one-half the original intensity and with vibrations in a single plane. The unpolarized light becomes polarized.
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A Polaroid filter is said to have a transmission axis. The filter can be thought of as having long-chain molecules that are aligned in the same direction within the filter. Unpolarized can be thought of as consisting of waves with electric and magnetic components of vibration that are directed in a multiple of planes. The electric and magnetic components that are aligned in the direction of the molecules become absorbed by the molecules. Those components that are perpendicular to the molecules emerge from the filter. Thus, the transmission axis is aligned perpendicular to the molecules of the filter. One-half of the original vibrations emerge from the filter, all aligned in a direction perpendicular to the molecules and parallel to the transmission axis.
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