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| Polarization | | A polarising sheet consists of long molecules embedded in plastic. When the sheet is manufactured, it is stretched to align the molecules in parallel rows, like rows in a plowed field. When light is then sent through the sheet, electric field components along the polarizing direction of the sheet pass through the sheet, while components perpendicular to that direction are absorbed by the molecules and disappear. | | Unpolarized light becomes polarized when it is sent through a polarizing sheet. Its direction of polarization is then parallel to the polarizing direction of the sheet, which is represented by the vertical lines in the sheet. If you look at unpolarized light through a polarization filter, you can rotate the filter in any direction, and the light will appear unchanged. | | | But if you look at the polarised light, then as you rotate the filter, you can progressively cut off more and more of the light until it is blocked out. An ideal polarization filters will transmit 50% of incident unpolarized light. That 50% is, of course, polarized. When two polarization filters are arranged so that their polarization axes are aligned, light will be transmitted through both of them. | | Previous | Next |
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