A Nicol prism is an optical device for producing a beam of plane polarized
light. Two pieces of calcite crystal
are cemented together with Canada balsam. Incident light is split into ordinary
and extraordinary linearly polarized rays in the prism. The ordinary ray
hits the balsam layer obliquely, and is totally internally reflected; the
other ray emerges plane polarized for a certain range of incident angles.
|Schematic section through a Nicol prism. The original
calcite rhombohedron is split along a diagonal plane, cemented back
together again with Canada balsam, and then ground down to the desired
shape. Optical polarimeters employ pairs of Nicol prisms.
The nicol prism was invented by the British physicist William Nicol (1768–1851).
It is used in the polarizing microscope, and also in geology to examine
thin sections of rock microscopically.
AND OPTICAL PHENOMENA