Nicol prism(redirected from William Nicol)
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Nicol prism(nĭk`əl), optical device invented (1828) by William Nicol of Edinburgh. It consists essentially of a crystal of calcite, or Iceland sparIceland spar,
colorless variety of crystallized calcite, characterized by its properties of transparency and double refraction. It is used chiefly in the manufacture of Nicol prisms, which are essential parts of polarizing microscopes and other optical instruments.
..... Click the link for more information. , that is cut at an angle into two equal pieces and joined together again with Canada balsam. An ordinary beam of light entering the crystal undergoes double refraction, i.e., is split into two parts, each of which is affected in a different way. One of these parts, the so-called ordinary ray, undergoes total reflection at the Canada-balsam joint and is turned off from its course to pass out at one side of the crystal. The other ray, the extraordinary ray, passes on through the crystal. By means of this device a beam of light can be polarized (see polarization of lightpolarization of light,
orientation of the vibration pattern of light waves in a singular plane. Characteristics of Polarization
Polarization is a phenomenon peculiar to transverse waves, i.e.
..... Click the link for more information. ) or a beam of polarized light can be subjected to analysis. The principle involved has been applied to the microscope in the illumination of the field.
an optical device that transmits only linearly polarized light that has a certain direction of polarization. This prism was invented in 1828 by the Scottish physicist W. Nicol. Made of Iceland spar, or calcite (CaCO3), it is one of the most widely used polarizing prisms.