How to Use a Polarimeter
A polarimeter determines the angle of optical rotation of polarized light as it passes through some material. Optical rotation is the process of turning the plane of polarized light about the direction of motion. The light waves of unpolarized light oscillate in all directions, while the waves of polarized light only oscillate in one direction. Solutions of certain types of substances such as sugar can polarize light; solid crystals may also be effective polarizers.
Instructions
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Select a light source. This may be a direct light source such as a light bulb, neon sign or TV screen, or an indirect light source such as a mirror or cloud.
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Set the polarimeter to zero degrees and view the selected object through the polarimeter. Rotate the lens of the polarimeter filter slowly until you have rotated it in a complete circle. Check for any changes in brightness. The light is unpolarized if its brightness does not change as you rotate the lens.
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Locate the polarimeter setting at which the light is brightest. This will generally require you to rotate the lens back and forth a few times to find the setting of maximum brightness.
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Read the setting that produces the maximum brightness. Settings of zero and 180 degrees indicate a completely vertical polarization, and settings of 90 and 270 degrees indicate complete horizontal polarization.
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Determine the degree of polarization. Locate the setting where the light is faintest and estimate the brightness of the faintest setting as a percentage of the brightest light. If no light at all can be seen on this setting, the light is completely polarized. If the brightness doesn't change, the light is completely unpolarized.
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